KR101852763B1 - Method for Manufacturing Electrodes for Secondary Battery Using Surface Plasmon Resonance - Google Patents

Abstract

(A) forming a pattern of a nanometer depth on a part or all of the surface of the current collector; (b) applying an electrode mixture including an electrode active material, a binder, and a conductive material to a surface of the current collector on which the pattern is formed; And (c) irradiating light on the surface of the current collector coated with the electrode mixture to induce surface plasmon resonance. The present invention also relates to a secondary battery electrode manufactured by the method.

Description

TECHNICAL FIELD [0001] The present invention relates to a surface plasmon resonance

The present invention relates to a method for manufacturing an electrode for a secondary battery using surface plasmon resonance, and an electrode for a secondary battery manufactured by the method.

Due to the rapid increase in the use of fossil fuels, the demand for the use of alternative energy or clean energy is increasing. As a part of this, the most active field of research is electric power generation and storage.

At present, a typical example of an electrochemical device utilizing such electrochemical energy is a secondary battery, and the use area thereof is gradually increasing.

2. Description of the Related Art [0002] Recently, as technology development and demand for portable devices such as portable computers, portable phones, and cameras have increased, the demand for secondary batteries as energy sources has increased sharply. Among such secondary batteries, they exhibit high energy density and operating potential, Many researches have been made on a lithium secondary battery having a long self discharge rate, and it has been commercialized and widely used.

Generally, a lithium secondary battery includes a lithium salt such as LiPF ₆ in an electrode assembly including a cathode including a lithium transition metal oxide as an electrode active material and a cathode including a carbonaceous active material, and a polyolefin porous separator interposed between the anode and the cathode. And a non-aqueous electrolytic solution containing a non-aqueous electrolyte solution is impregnated.

Specifically, the positive electrode and the negative electrode are prepared by applying an electrode mixture containing an electrode active material, a conductive material, and a binder on a current collector using copper or aluminum foil as a current collector, and drying. In particular, the binder is a component added to adhere the electrode active material to the current collector, and affects the performance and safety of the lithium secondary battery depending on the type and content of the binder.

For example, the lithium secondary battery is repeatedly shrunk and expanded due to lithium ions during charging and discharging, so that the coupling force between the electrode mixture and the current collector is lowered, and the contact resistance of that portion is increased. Furthermore, a side reaction occurs at a portion where the contact resistance is increased, and the life of the battery deteriorates, and the output characteristics of the battery also deteriorate due to the high resistance.

In addition, when the bonding force between the electrode mixture and the current collector is low, the electrode mixture may be separated from the current collector, resulting in a local short circuit with the opposite electrode, which is also detrimental to the safety of the battery.

In order to solve this problem, if the content of the binder is increased, the overall performance of the battery deteriorates due to an increase in the resistance of the battery due to the electrically non-conductive binder and a decrease in the amount of the active material relative to that of the binder. Increasing the content has limitations.

Conventionally, attempts have been made to solve these problems by applying a method of applying an electrode mixture to a current collector and drying the electrode mixture. Specifically, it has been confirmed that if the drying condition of the electrode mixture is poor, the binder moves in a direction opposite to the surface of the current collector in the electrode mixture, and the adhesion between the electrode mixture and the current collector is lowered. There has been an attempt to dry the current collector at a low temperature or to keep the drying time very long. However, in this case, it takes a long time to manufacture the electrode, and the process cost is increased.

Therefore, there is a high need for a technique capable of enhancing the bonding force between the electrode assembly and the current collector so as to improve the safety of the electrode and improve the life characteristics and output characteristics of the battery.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments, and have found that, as will be described later, the process of forming a pattern with a nanometer depth on the surface of a current collector, a process of applying an electrode mixture containing a binder, And irradiating light to the surface plasmon resonance to induce surface plasmon resonance, it has been found that an unexpectedly excellent effect can be achieved, and the present invention has been accomplished.

Accordingly, a method of manufacturing an electrode for a secondary battery according to the present invention includes the steps of: (a) forming a pattern having a nanometer depth on part or all of a surface of a current collector; (b) applying an electrode mixture including an electrode active material, a binder, and a conductive material to a surface of the current collector on which the pattern is formed; And (c) inducing surface plasmon resonance by irradiating light onto the surface of the current collector coated with the electrode mixture.

In the step (c), the electrode mixture may be dried while irradiating the surface of the collector coated with the electrode mixture.

After the step (c), the process may further include the following steps:

(d) drying the current collector irradiated with the light.

The pattern may be a relief or a relief pattern, and the pattern may be formed to a depth of 1 to 900 nm, and more specifically, a depth of 1 to 200 nm.

The pattern may be formed through a physical or chemical surface treatment, and in particular, the surface treatment may be a chemical etching.

The wavelength of the light may be 10 to 1000 nm, and more specifically 350 to 500 nm. Further, the light may be laser light.

In step (c), the light may be irradiated for 1 to 30 seconds.

The aromatic compound may be an alcohol group, a thiol group, a carboxyl group, a nitrate group, a nitrite group, an amine group, a nitrile group, An imine group, a cyano group, a disulfide group, a sulfuric acid group and a sulfurous group.

The current collector may have a thickness of 3 to 500 mu m.

In the step (b), the electrode mixture may be applied in a thickness of 100 to 1500 μm.

The present invention also provides an electrode for a secondary battery manufactured by the above manufacturing method, and provides the lithium secondary battery including the electrode for the secondary battery.

The present invention also provides a battery pack including the lithium secondary battery as a unit cell, and a device including the battery pack.

The device may be, for example, a computer, a mobile phone, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle, a plug- A power storage system, and the like.

As described above, the method for manufacturing an electrode for a secondary battery according to the present invention includes the steps of forming a pattern having a nanometer depth on the surface of a current collector, applying an electrode mixture containing a binder, And enhancing the bonding force between the current collector and the electrode mixture, including a process of inducing surface plasmon resonance, thereby improving the safety of the electrode, the lifetime characteristics of the battery, and the output characteristics.

Hereinafter, an embodiment of the present invention will be described, but it is to be understood that the scope of the present invention is not limited thereto.

A method of manufacturing an electrode for a secondary battery according to the present invention includes the steps of: (a) forming a pattern having a nanometer depth on a part or all of a surface of a current collector; (b) applying an electrode mixture including an electrode active material, a binder, and a conductive material to a surface of the current collector on which the pattern is formed; And (c) inducing surface plasmon resonance by irradiating light onto the surface of the current collector coated with the electrode mixture.

Surface plasmon resonance (SPR) is a phenomenon in which electrons are concentrated on the surface of a metal structure when irradiated with light of a nanometer-sized metal structure, resulting in vibrating and exciting surface states. Thus, surface plasmon resonance The excited metal surface sucks the material present in the vicinity.

Therefore, when a pattern of a nanometer depth is formed on the surface of the current collector, and an electrode mixture containing a binder is applied, light is irradiated to the surface of the current collector, surface plasmon resonance occurs in the pattern of the surface of the current collector, , The electrode mixture applied on the surface of the current collector, particularly the binder, is attracted to the surface of the current collector, so that the bonding force between the current collector and the electrode mixture is improved.

In one specific example, the pattern is not particularly limited as long as it is a nanometer depth that can induce surface plasmon resonance, but it may be a shape with a relief or a depressed shape, a structure formed with a depth of 1 to 900 nm, May be formed at a depth of 1 to 200 nm. When the depth of the pattern is less than 1 nm or exceeds 900 nm, surface plasmon resonance is not induced well.

On the other hand, the pattern may be formed through physical or chemical surface treatment, and in detail, may be formed by chemical etching, but is not limited thereto.

In addition, the wavelength of the light may be 10 to 1000 nm, and more specifically 350 to 500 nm. The wavelength of such light can be appropriately selected depending on the kind of metal material constituting the collector and the depth and shape of the pattern.

The light may be laser light, and the laser light has a stronger energy than that of the ordinary light, so that it can induce surface plasmon resonance in a short time.

In one specific example, the electrode mixture in step (b) may be applied in a thickness of 100 to 1500 [mu] m. It is difficult to secure the capacity of the battery when it is applied to a thickness of less than 100 μm and when the thickness of the electrode mixture is more than 1500 μm, the thickness of the electrode mixture becomes too thick, It is difficult to reach the surface of the current collector through permeation, so that it is difficult to induce surface plasmon resonance.

In one specific example, in the step (c), the electrode mixture can be dried while simultaneously irradiating the surface of the current collector coated with the electrode mixture. In this case, since no separate step of irradiating light to the electrode mixture is required, it is possible to shorten the electrode manufacturing process time.

In the process (c), the light can be irradiated for 1 to 30 seconds, and specifically, for 5 to 20 seconds. If irradiation is performed for less than 1 second, sufficient energy is not supplied, surface plasmon resonance may be difficult to induce, and if irradiated for more than 30 seconds, energy efficiency may be lowered in the entire process.

Meanwhile, after the step (c), the method may further include the following step (d):

(d) drying the current collector irradiated with the light.

When the step (d) is included, the electrode mixture is dried in the state that the current collector sucks the binder by surface plasmon resonance, which is advantageous from the viewpoint of improving the bonding force and it takes much time to induce surface plasmon resonance So that the electrode manufacturing process is not significantly delayed.

In one specific example, the binder may be a polymer in which one or more monomers are polymerized, and may include from 1 wt% to 30 wt%, based on the total weight of the electrode mixture. Also, the monomer may include at least one aromatic compound, and the aromatic compound may be at least one selected from the group consisting of an alcohol group, a thiol group, a carboxyl group, a nitric group, a nitrite group, an amine group, an imine group, a cyan group, a disulfide group, And at least one functional group selected from the group consisting of

In order to improve the binding force between the current collector and the electrode mixture, it is necessary to attract the binder in the current collecting direction. According to the inventors of the present invention, when the monomer constituting the binder contains an aromatic compound, The bonding force of the mixture improves. These results are presumed to be due to the fact that the electrons concentrated on the surface of the collector by surface plasmon resonance interact with the aromatic compounds rich in electrons to increase the attraction force.

When the aromatic compound includes at least one functional group selected from the group consisting of an alcohol group, a thiol group, a carboxyl group, a nitric acid group, a nitrite group, an amine group, an imine group, a cyan group, a disulfide group, a sulfuric acid group and a sulfurous group, The interaction between the electrons concentrated on the surface and the binder polymer is further increased and the bonding force is further improved.

The current collector may have a thickness of 3 to 500 mu m. Such a current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. Examples of the positive electrode collector include stainless steel, aluminum, nickel, titanium, sintered carbon, or aluminum Carbon, nickel, titanium, silver, or the like may be used on the surface of stainless steel or stainless steel.

Examples of the anode current collector include those obtained by surface-treating a surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel with carbon, nickel, Alloys and the like may be used.

The positive electrode or negative electrode current collector may 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 cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or the like, or one or more transition metals, for example, as a cathode active material or an anode active material. Substituted compounds; Lithium manganese oxides such as Li _{1 + x} Mn _{2 -x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ and the like; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiV ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _1-x M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2-x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = 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; Lithium nickel manganese cobalt composite oxides such as LiNi _1/3 Mn _1/3 Co _1/3 O ₂ and LiNi _0.5 Mn _0.3 Ni _0.2 ; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and LiNi _x Mn _2-x O ₄ (0.01 _{? X?} 0.6).

The negative electrode active material may be, for example, graphite having a completely layered crystal structure such as natural graphite, soft carbon having a low crystalline layered crystal structure (a structure in which hexagonal honeycomb planes of carbon are arranged in layers) Carbon and graphite materials such as hard carbon, artificial graphite, expanded graphite, carbon fiber, hard graphitizable carbon, carbon black, carbon nanotube, fullerene, activated carbon and the like in which structures are mixed with amorphous portions; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1-x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x &lt; Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials and the like; Complexes of the above compounds may be used.

The conductive material is usually added in an amount of 1 to 30% by weight based on the total weight of the electrode mixture including the electrode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, 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 whiskey 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 electrode mixture may further include a filler. The filler is selectively used as a component for suppressing the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing a chemical change in the battery. For example, , Olefin-based polymerization agents such as polyethylene and polypropylene; Fibrous materials such as glass fiber, carbon fiber and the like can be used.

The present invention also provides an electrode for a secondary battery manufactured by the above manufacturing method, wherein the electrode assembly including the electrode and the separator is embedded in the battery case together with the non-aqueous electrolyte.

The separation membrane is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used. The pore diameter of the separator is generally 0.01 to 10 mu m and the thickness is generally 5 to 300 mu m. Such separation membranes include, for example, olefinic polymers such as polypropylene, which are chemically resistant and hydrophobic; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid electrolyte such as a polymer is used as an electrolyte, the solid electrolyte may also serve as a separation membrane.

The non-aqueous electrolyte is composed of a non-aqueous electrolyte and a lithium salt, and examples of the non-aqueous electrolyte include non-aqueous organic solvents, organic solid electrolytes, inorganic solid electrolytes, and the like.

Examples of the non-aqueous organic solvent include N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma -Butyrolactone, 1,2-dimethoxyethane, tetrahydroxyfuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile , Nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxymethane, dioxolane derivatives, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, Tetrahydrofuran derivatives, ether, methyl pyrophosphate, ethyl propionate and the like can be used.

Examples of the organic solid electrolyte include a polymer electrolyte such as a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, an agitation lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene fluoride, A polymer containing an ionic dissociation group and the like may be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, LiSiO ₄ , LiSiO ₄ -LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Nitrides, halides and sulfates of Li such as Li ₄ SiO ₄ -LiI-LiOH and Li ₃ PO ₄ -Li ₂ S-SiS ₂ can be used.

The lithium salt is a substance that is soluble in the nonaqueous electrolyte and includes, for example, LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, chloroborane lithium, lower aliphatic carboxylate lithium, lithium tetraphenylborate, and imide.

The nonaqueous electrolyte may contain, for the purpose of improving charge / discharge characteristics, flame retardancy, etc., for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, N, N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, aluminum trichloride and the like may be added have. In some cases, halogen-containing solvents such as carbon tetrachloride and ethylene trifluoride may be further added to impart nonflammability. In order to improve the high-temperature storage characteristics, carbon dioxide gas may be further added. FEC (Fluoro-Ethylene Carbonate, PRS (Propene sultone), and the like.

In one specific _{example, LiPF 6, LiClO 4, LiBF} 4, LiN (SO 2 CF 3) 2 , such as a lithium salt, a highly dielectric solvent of DEC, DMC or EMC Fig solvent cyclic carbonate and a low viscosity of the EC or PC of And then adding it to a mixed solvent of linear carbonate to prepare a lithium salt-containing nonaqueous electrolyte.

The battery case may be a pouch-shaped battery case made of a laminate sheet including an outer coating layer made of a weatherproof polymer, an inner sealant layer made of a heat-sealable polymer, and a barrier layer interposed between the outer coating layer and the inner sealant layer Specifically, a pouch-shaped battery case made of an aluminum laminate sheet having a barrier layer of Al.

The present invention also provides a battery pack including the lithium secondary battery as a unit cell, and a device including the battery pack.

Specific examples of such a device include a small device such as a computer, a mobile phone, a power tool, a power tool powered by an electric motor, An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; Power storage systems, and the like, but are not limited thereto.

The structure of the battery pack and the device is well known in the art, so a detailed description thereof will be omitted herein.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (22)

A method of manufacturing an electrode for a secondary battery,
(a) forming a pattern having a nanometer depth on part or all of the surface of the current collector;
(b) applying an electrode mixture including an electrode active material, a binder, and a conductive material to a surface of the current collector on which the pattern is formed; And
(c) irradiating a surface of the current collector coated with the electrode mixture to light to induce surface plasmon resonance,
The pattern is formed to a depth of 1 to 900 nm,
Wherein the binder contains at least one aromatic compound containing at least one functional group selected from the group consisting of an alcohol group, a thiol group, a carboxyl group, a nitric group, a nitrite group, an amine group, an imine group, a cyan group, a disulfide group, Polymerized polymer
&Lt; / RTI &gt; The manufacturing method according to claim 1, wherein in the step (c), the electrode mixture is dried while irradiating the surface of the current collector coated with the electrode mixture. The method according to claim 1, further comprising the step of: after the step (c)
(d) drying the current collector irradiated with the light. 2. The method of claim 1, wherein the pattern is a relief or relief pattern. delete The method of claim 1, wherein the pattern is formed to a depth of 1 to 200 nm. The method of claim 1, wherein the pattern is formed through a physical or chemical surface treatment. 8. The method of claim 7, wherein the surface treatment is chemical etching. The method according to claim 1, wherein the wavelength of the light is 10 to 1000 nm. The method according to claim 1, wherein the wavelength of the light is from 350 to 500 nm. The method according to claim 1, wherein the light is laser light. 2. The method according to claim 1, wherein light is irradiated for 1 to 30 seconds in the step (c). delete delete delete The manufacturing method according to claim 1, wherein the current collector has a thickness of 3 to 500 탆. The method according to claim 1, wherein the electrode mixture is applied in a thickness of 100 to 1500 占 퐉 in step (b). delete delete delete delete delete