WO2014038836A2 - Binder for electrode composition and secondary battery comprising same - Google Patents

Binder for electrode composition and secondary battery comprising same Download PDF

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Publication number
WO2014038836A2
WO2014038836A2 PCT/KR2013/007947 KR2013007947W WO2014038836A2 WO 2014038836 A2 WO2014038836 A2 WO 2014038836A2 KR 2013007947 W KR2013007947 W KR 2013007947W WO 2014038836 A2 WO2014038836 A2 WO 2014038836A2
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Prior art keywords
cmc
weight
electrode mixture
electrode
binder
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PCT/KR2013/007947
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French (fr)
Korean (ko)
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WO2014038836A3 (en
Inventor
이원민
장명석
안병화
정선옥
Original Assignee
주식회사 지엘켐
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Priority to CN201380020844.6A priority Critical patent/CN104302671B/en
Publication of WO2014038836A2 publication Critical patent/WO2014038836A2/en
Publication of WO2014038836A3 publication Critical patent/WO2014038836A3/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/08—Cellulose derivatives
    • C08L1/26—Cellulose ethers
    • C08L1/28—Alkyl ethers
    • C08L1/286—Alkyl ethers substituted with acid radicals, e.g. carboxymethyl cellulose [CMC]
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
    • C08B11/00—Preparation of cellulose ethers
    • C08B11/02—Alkyl or cycloalkyl ethers
    • C08B11/04—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals
    • C08B11/10—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals substituted with acid radicals
    • C08B11/12—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals substituted with acid radicals substituted with carboxylic radicals, e.g. carboxymethylcellulose [CMC]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/34—Gastight accumulators
    • H01M10/345—Gastight metal hydride accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a binder for electrode mixture and a secondary battery comprising the same.
  • Secondary batteries are rechargeable, easy to miniaturize, and large in capacity, and typically include nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.
  • Ni-MH nickel-hydrogen
  • Li lithium
  • Li-ion lithium ion
  • the lithium ion battery uses lithium-transition metal oxide as the positive electrode active material, carbon or carbon composite material as the negative electrode active material, and a liquid electrolyte in which lithium salt is dissolved in one or more organic solvents including an oxygen group, a nitrogen group, and a sulfate group. It is used to generate an electromotive force when lithium ions are moved between the positive electrode and the negative electrode so that charging and discharging are performed.
  • electrodes such as a positive electrode and a negative electrode are somewhat different depending on the type of battery, but are made of an active material made of lithium-transition metal oxide and carbon and polyvinylidene fluoride (PVDF).
  • a slurry is prepared by mixing a binder, an organic solvent of N-methyl-2-pyrrolidone (NMP) and a conductive agent of carbon (for positive electrode), and then aluminium (Al) and copper (Cu) It is manufactured by the process of coating on the base material of foil, drying and roll-pressing again, and then cutting to predetermined size.
  • NMP N-methyl-2-pyrrolidone
  • Cu aluminium
  • It is manufactured by the process of coating on the base material of foil, drying and roll-pressing again, and then cutting to predetermined size.
  • the binder used in the above electrode production has excellent high-rate charging and discharging characteristics, but the adhesive force is weak, resulting in dropping of the active material, which in turn reduces the life of the battery.
  • US Pat. No. 5,380,606 discloses a binder of an electrode as polyamic acid, polyamide resin, polyvinylpyrrolidone and hydroxyalkylcellulose. It is proposed a mixed binder containing at least one polymer selected from the group selected to improve the life and reliability of the battery.
  • the above-mentioned mixed binder has to be subjected to high temperature heat treatment at 200 to 400 ° C. in order to remove the polyamic acid added during the drying process of the electrode plate, so that the operation of the process is complicated and difficult, and the physical properties of the electrode change during the heat treatment. There is this.
  • SBR styrene butadiene rubber
  • carboxymethyl cellulose (hereinafter referred to as 'CMC') is an environmentally friendly binder that dissolves or disperses well in water and satisfies conditions such as electrochemical stability, insolubility to organic solvents, and adhesion. Known.
  • the present inventors have found a binder and a method for producing the same, which are electrochemically stable and have a bonding force capable of adhering an active material to a substrate without being dissolved in an organic solvent in a battery, thereby completing the present invention.
  • the present invention can increase the dispersion of the conductive agent in the electrode mixture and increase the electrolyte absorption of the electrode, thereby improving the battery characteristics such as initial capacity, cycle characteristics, etc. of the finished battery To provide a new composition ratio of the electrode mixture CMC.
  • the present invention is to provide a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC.
  • the present invention for achieving this purpose is to increase the dispersion of the conductive agent in the electrode mixture and to increase the electrolyte absorption of the electrode, the electrode composition of a new composition ratio that can improve the battery characteristics such as initial capacity, cycle characteristics of the finished battery It provides a method for producing a CMC.
  • the present invention provides a CMC for electrode mixture having a weight average molecular weight (Mw) 800,000 to 900,000 prepared by the above method.
  • the present invention provides a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC.
  • the binder according to the present invention is characterized in that the weight average molecular weight (Mw) 800,000 to 900,000 as a binder for electrode mixture of the secondary battery.
  • the binder according to the present invention is a binder for electrode mixture of a secondary battery, the viscosity is 250 to 300 cps when the substitution degree is 1 to 2, 1% by weight of an aqueous solution, the content of metal ions measured by ICP analysis is 150 to 250 ppm.
  • CMC for electrode mixture has a weight average molecular weight (Mw) of 1,000,000 to 5,000,000 natural cellulose 1 to 40% by weight, IPA (isopropanol) and ethanol mixed alcohol 10 to 80% by weight, sodium hydroxide (NaOH) 1 to 30 It provides a CMC composition for electrode mixture comprising a weight%, 1 to 30% by weight chloroacetic acid (MCA).
  • Mw weight average molecular weight
  • IPA isopropanol
  • NaOH sodium hydroxide
  • the natural cellulose may be a mixed pulp of cotton fiber pulp and wood pulp, the mixing ratio of the cotton fiber pulp and wood pulp is a weight ratio, the weight ratio is preferably 1: 1, but is not limited thereto. .
  • the CMC for electrode mixture according to the present invention is 1 to 40% by weight of natural cellulose, preferably 10 to 30% by weight. If it is less than 1% by weight, the coating state of the surface of the active material is insufficient, and the contact area between the surface of the active material and the electrolyte is wide, resulting in poor battery safety. Moreover, there exists a problem that the adhesiveness of the electrode of a polymer and an electrical power collector, or binding property between electrode active materials falls, and the discharge capacity in a repetitive first discharge falls.
  • the film formed on the surface of the electrode becomes too thick, the lithium ion permeability at the interface between the electrode active material and the electrolyte is poor, the internal resistance increases, and there is a problem that the first discharge capacity is lowered.
  • the present invention is a.
  • Mw weight average molecular weight
  • the present invention is a CMC (sodium carboxymethyl cellulose) prepared by the above method, the weight average molecular weight (Mw) of 800,000 to 900,000, when the substitution degree of 1 to 2, the aqueous solution of 1% by weight of 250 to 300 cps, ICP analysis It provides a CMC for electrode mixture, characterized in that the content of the metal ion is measured by 150 to 250 ppm.
  • Mw sodium carboxymethyl cellulose
  • Natural cellulose according to the present invention can be used that the weight average molecular weight (Mw) is 1,000,000 to 5,000,000, more preferably 2,500,000 to 3,500,000 can be used.
  • the weight average molecular weight (Mw) of the natural cellulose is less than 1,000,000, it is difficult to exert the electrolytic solution and elastic force in the electrode mixture binder of the secondary battery produced, resulting in a decrease in adhesive strength and a charge and discharge efficiency, and when exceeded 5,000,000, Absorption and swelling of excess electrolyte due to high affinity may cause detachment of the electrode from the current collector, which is not preferable.
  • the sodium hydroxide concentration of step 1) is characterized in that 50%.
  • the chloroacetic acid concentration of step 3 is characterized in that 30%.
  • the hydrochloric acid, nitric acid or chelating agent of step 4) has an important meaning for the removal of metal impurities present in the CMC prepared by using the reactivity of the metal as well as the neutralization of the reactants and obtaining a high purity CMC.
  • the chelating agent may use ethylenediaminetetraacetic acid (EDTA), preferably one or more selected from EDTA-2Na, EDTA-3Na or EDTA-4Na, but is not limited thereto.
  • EDTA ethylenediaminetetraacetic acid
  • the Zn metal ion is separated from the metal indicator. It can be separated and combined with EDTA-4Na or citric acid to extract Zn impurities.
  • the step 4) according to the present invention Has an important meaning.
  • the CMC is produced by the above method, characterized in that the content of metal ions measured by ICP analysis is 150 to 250 ppm.
  • the CMC is prepared by the above method, the degree of substitution is 1 to 1.5, characterized in that the viscosity when the aqueous solution 1% by weight is 250 to 300 cps.
  • CMC is water soluble, but like other water soluble polymers, it swells during dissolution and dissolves slowly.
  • the degree of substitution of the CMC according to the present invention has a viscosity of less than 1 or 1% by weight of an aqueous solution of less than 250 cps, it is difficult for a binder to bind to the surface of the inorganic particles, and when the degree of substitution is more than 1.5 or 1% by weight of an aqueous solution.
  • the viscosity exceeds 300 cps, dissolution in a hydrophilic organic solvent occurs, which causes uneven reactions or imparts a viscosity of the binder to maintain the strength during manufacture of the electrode plate, which is not preferable.
  • the present invention provides a secondary battery electrode, characterized in that prepared by the electrode mixture prepared by the CMC (sodium Carboxymethyl cellulose).
  • the content of metal ions measured by ICP analysis is 150 to 250 ppm It provides a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC characterized in that.
  • the secondary battery electrode is manufactured by coating an electrode mixture, in which an electrode active material, a binder, and optionally a conductive agent, a filler, and the like are mixed with a current collector.
  • the electrode mixture may be added to a predetermined solvent to prepare an electrode slurry, and then coated on a current collector such as a metal foil, dried, and rolled to prepare a predetermined sheet-shaped electrode.
  • the binder can be used both as a binder of the negative electrode and / or a positive electrode, more preferably used as a binder of the negative electrode.
  • a binder having a high capacity but having a large volume change during charging and discharging may be a preferred binder when a silicon-based active material, a tin-based active material, a silicon-carbon-based active material, or the like is used as the negative electrode active material.
  • the silicon or tin-based negative active material is meant to include silicon (Si) particles, tin (Sn) particles, silicon-tin alloys, their respective alloy particles, composites, and the like.
  • Typical examples of the alloy include, but are not limited to, solid solutions such as aluminum (Al), manganese (Mn), iron (Fe), titanium (Ti), intermetallic compounds, eutectic alloys, and the like.
  • the binder may be included in about 1 to 50% by weight, preferably 2 to 20% by weight based on the total weight of the electrode mixture. If the content of the binder is too small, it is difficult to expect a role as a binder capable of withstanding the volume change generated during charging and discharging. On the contrary, the content of the binder is too high because it causes a decrease in the electrode capacity and an increase in resistance.
  • Preferred examples of the solvent used in the preparation of the electrode slurry include dimethyl sulfoxide (DMSO), N-methyl pyrrolidon (NMP), and the like. It can be used up to 400% by weight and is removed during the drying process.
  • DMSO dimethyl sulfoxide
  • NMP N-methyl pyrrolidon
  • the electrode mixture as described above may further include other components, such as a viscosity modifier, a conductive agent, a filler, a coupling agent, an adhesion promoter, or a combination of two or more thereof.
  • the viscosity modifier is a component that adjusts the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector thereof can be facilitated.
  • examples of such viscosity regulators include polyvinylidene fluoride, It is not limited.
  • the solvent described above can serve as a viscosity modifier.
  • the conductive agent is a component for further improving the conductivity of the electrode active material, and the conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • natural graphite or artificial graphite may be used.
  • Graphite Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black;
  • Conductive fibers such as carbon fibers and metal fibers;
  • Metal powders such as carbon fluoride powder, aluminum powder and nickel powder;
  • Conductive whiskeys 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 filler is an auxiliary component that suppresses the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing chemical changes in the battery.
  • the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.
  • the coupling agent is an auxiliary component for increasing the adhesion between the active material and the binder, characterized in that it has two or more functional groups, such a coupling agent, for example, one functional group is silicon, tin, or graphite It may be a material that reacts with a hydroxyl group or a carboxyl group on the surface of the active material to form a chemical bond, and other functional groups form a chemical bond through a reaction with the polymer binder.
  • the coupling agent include triethoxysilylpropyl tetrasulfide, mercaptopropyl triethoxysilane, aminopropyl triethoxysilane, and chloropropyl triethoxysilane ( chloropropyl triethoxysilane, vinyl triethoxysilane, methacryloxypropyl triethoxysilane, glycidoxypropyl triethoxysilane, isocyanatepropyl triethoxysilane (isocyanatopropyl Silane coupling agents, such as triethoxysilane) and cyanatopropyl triethoxysilane, are mentioned, but it is not limited to these.
  • the adhesion promoter is an auxiliary component added to improve the adhesion of the negative electrode active material to the current collector, for example oxalic acid, adipic acid, formic acid, acrylic acid Derivatives, itaconic acid derivatives, and the like.
  • a current collector is a site where electrons move in an electrochemical reaction of an active material, and a negative electrode current collector and a positive electrode current collector exist.
  • the negative electrode current collector is generally made to a thickness of 3 to 500 ⁇ m.
  • Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery.
  • the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used.
  • the positive electrode current collector is generally made to a thickness of 3 to 500 ⁇ m.
  • Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery.
  • the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like may be used.
  • These current collectors may form fine concavities and convexities on the surface thereof to enhance the bonding strength of the electrode active material, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.
  • the electrode active materials a carbon-based material, a silicon-based material, a tin-based material, and a silicon-carbon-based material may be used as the negative electrode active material, and the positive electrode active material may be lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), or the like.
  • the bonding strength between the active materials and the current collector can be stably maintained despite the large volume change of the negative electrode active materials during charging and discharging, and cracks due to the volume expansion of the active materials Since it can minimize the commercialization of a high capacity silicon or tin-based negative electrode active material can greatly contribute to the production of large capacity lithium secondary battery.
  • FIG. 1 is a graph illustrating a C-rate ratio of an electrode manufactured by using sodium carboxymethyl cellulose (CMC) according to the present invention.
  • FIG. 2 is a graph showing the discharge capacity recovery rate after the initial cycle and 500 cycles of the electrode prepared by including the sodium carboxymethyl cellulose (CMC) according to the present invention
  • Cell-G using CMC of preparation example
  • Cell-N using CMC of control (HB-45: Daiichi Japan)
  • Figure 3 is a graph of the peel strength of the electrode prepared including the CMC (sodium Carboxymethyl cellulose) according to the present invention.
  • IPA isopropanol
  • ethanol in cellulose mixed with 3,000,000 cotton fiber pulp and softwood pulp (Canada kamloops acid) in a weight ratio of 1,000,000 cotton by weight average molecular weight (Mw) 54% by weight of alcohol was added to the kneader stirrer (high viscosity stirrer), followed by stirring for 1 h while maintaining 37 ° C. for mercerization reaction.
  • a CMC powder was prepared in the same manner as in Preparation Example 1, except that 45% NaOH aqueous solution was added during mercerization, and 30% monochloroacetic acid (MCA) aqueous solution was used during etherification.
  • MCA monochloroacetic acid
  • the viscosity of the CMC of Preparation Example and CMC of Comparative Preparation Examples 1 to 6 was measured. The viscosity was measured using a Brookfield Viscometer in the following manner. CMC (HB-45: manufactured by Daiichi Japan) was used as a control.
  • a solution of 2% was prepared by dissolving 6 g of each CMC powder of Preparation Example and Comparative Preparation Example in 294 g of distilled water.
  • the viscosity at 1% by weight of the aqueous solution was 270 cps or more, which was similar to that of the control CMC (HB-45: manufactured by Daiichi Japan). In the case of the production example, it was confirmed that the viscosity shows a viscosity of 245 cps or less.
  • the above result is also a result confirming that the CMC of the present invention can maintain or increase the lifespan characteristics of a battery manufactured as a binder for electrode mixture.
  • the metal component content of CMC of the said manufacture example and CMC of the comparative manufacture examples 1-6 was investigated.
  • the metal content was measured by inductively coupled plasma (ICP) analysis.
  • CMC (HB-45: manufactured by Daiichi Japan) was used as a control.
  • the above result is also a result of confirming that the CMC of the present invention can improve the characteristics of a battery produced as a binder for electrode mixture and maintain or increase the lifespan characteristics of the battery.
  • the CMC of Preparation Example 2 having the best evaluated physical properties among the Preparation Examples and the CMC of Comparative Preparation Example 3 having the best evaluated physical properties among the Comparative Preparation Examples were selected, and the conventional battery was prepared including the selected CMC.
  • the battery was manufactured by the method.
  • CMC HB-45: manufactured by Daiichi Japan
  • the discharge capacity for each C-rate was measured, and the discharge efficiency was calculated by converting it into a percentage.
  • the discharge efficiency was calculated by comparing the discharge capacity for each C-rate with respect to the initial discharge capacity (0.2C discharge capacity), which is the standard discharge capacity, and the discharge capacity for each C-rate is 0.2C, the reference discharge capacity.
  • 0.2C discharge capacity the initial discharge capacity
  • the discharge capacity for each C-rate is 0.2C
  • the reference discharge capacity 0.5C, 1.0C, 2C discharge capacity, 2C discharge capacity compared to 0.2C was measured.
  • the secondary battery having a rated capacity of 1000 mAh is charged or discharged at a current value of 500 mAh, it is referred to as 0.5C charging or 0.5C discharge.
  • the concept of C-rate is used to indicate charging or discharging.
  • the C-rate may be simply defined as the current capacity ratio per hour.
  • 0.5C discharge capacity compared to 0.2C means the discharge capacity when discharged at 0.5C
  • 0.5C discharge efficiency compared to 0.2C is 0.5 when discharged at 0.2C It means the discharge efficiency compared with the discharge capacity when discharged at C.
  • the discharge is performed with a larger current, which means that the discharge is completed at a faster time. In other words, it means that the capacity of the current discharged within the same time is larger than 0.5C.
  • the discharge efficiency is lower than that of the comparative example in the case of the comparative manufacturing example, in particular, in the case of 2.0C discharge compared to 0.2C, the discharge efficiency is significantly lower than the manufacturing example. It can be seen.
  • the battery of the production example was confirmed that all excellent in terms of initial capacity, efficiency, cycle capacity retention rate, the initial efficiency and initial capacity was similar to the battery using the CMC of the control, the battery It was confirmed that the cycle characteristics of the similar.
  • a 50 ⁇ m polyimide film was bonded to both sides of the adhesive film with a hot roll laminate (80 ° C., 0.3 m / min, 0.3 MPa) by an experimental method, and cured at 170 ° C. for 1 hour.
  • the laminated cured material was cut into width 10mm, and it produced into the evaluation sample.
  • the value at the time of peeling at a tensile speed of 50 mm / min at the angle of 180 degree using the UTM-4-100 type tensilon made from T0Y0 BALWIN was calculated
  • the CMC of the present invention has excellent binder properties for electrode mixture that overcomes the reliability of the quality in the replacement of the binder depending on the existing imports.

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Abstract

The present invention relates to a binder for an electrode composition and a secondary battery comprising the same and, more specifically, to a CMC for an electrode composition and a method for manufacturing the same. When the CMC of the present invention is used as a binder for an electrode composition, binding forces between active materials and an active material and a current collector can be stably maintained despite large changes in volume of cathode active materials during charging and discharging, and cracks due to the volume expansion of cathode active materials are minimized such that commercial use of high volume silicon- or tin-based cathode active materials is possible, thereby contributing to the manufacture of high-capacity lithium secondary batteries.

Description

전극 합제용 바인더 및 이를 포함하는 이차전지Binder for electrode mixture and secondary battery comprising same
본 발명은 전극 합제용 바인더 및 이를 포함하는 이차전지에 관한 것이다.The present invention relates to a binder for electrode mixture and a secondary battery comprising the same.
이차전지는 재충전이 가능하고 소형 및 대용량화가 용이한 것으로, 대표적으로는 니켈수소(Ni-MH)전지, 리튬(Li)전지 및 리튬이온(Li-ion)전지가 사용되고 있다.Secondary batteries are rechargeable, easy to miniaturize, and large in capacity, and typically include nickel-hydrogen (Ni-MH) batteries, lithium (Li) batteries, and lithium ion (Li-ion) batteries.
여기서 리튬이온전지는 정극 활물질로 리튬-전이금속산화물이 사용되고, 부극 활물질로 카본 혹은 카본복합체가 사용되며, 산소기, 질소기, 황산기 등을 포함하는 한 개 이상의 유기 용매에 리튬 염을 녹인 액체 전해질이 사용되어서, 정극과 부극간에 리튬 이온이 이동될 때 기전력을 발생시킴으로써 충·방전이 이루어지도록 한다.Here, the lithium ion battery uses lithium-transition metal oxide as the positive electrode active material, carbon or carbon composite material as the negative electrode active material, and a liquid electrolyte in which lithium salt is dissolved in one or more organic solvents including an oxygen group, a nitrogen group, and a sulfate group. It is used to generate an electromotive force when lithium ions are moved between the positive electrode and the negative electrode so that charging and discharging are performed.
이러한 리튬이온전지에서 정극 및 부극과 같은 전극(電極)은 전지의 종류에 따라 다소 차이가 있지만, 리튬-전이금속산화물 및 카본으로 된 활물질과, 폴리비닐리덴 플로라이드(PVDF; polyvinylidene fluoride)로 된 바인더 및 N-메틸 피롤리돈(NMP; N-methyl-2-pyrrolidone)으로 된 유기 용매, 카본으로 된 도전제(정극의 경우)를 혼합하여 슬러리를 제조한 다음, 이것을 알루미늄(Al) 및 구리(Cu) 호일로 된 기재에 코팅하고, 다시 건조 및 롤 프레스 한 다음 소정의 크기로 절단하는 공정에 의해 제조하고 있다.In such a lithium ion battery, electrodes such as a positive electrode and a negative electrode are somewhat different depending on the type of battery, but are made of an active material made of lithium-transition metal oxide and carbon and polyvinylidene fluoride (PVDF). A slurry is prepared by mixing a binder, an organic solvent of N-methyl-2-pyrrolidone (NMP) and a conductive agent of carbon (for positive electrode), and then aluminium (Al) and copper (Cu) It is manufactured by the process of coating on the base material of foil, drying and roll-pressing again, and then cutting to predetermined size.
그러나 상기한 전극 제조에 사용하는 바인더는 고율 충, 방전특성이 우수한 반면, 접착력이 약하여 활물질의 탈락이 발생하므로 결국 전지의 수명을 저하시키고 있다.However, the binder used in the above electrode production has excellent high-rate charging and discharging characteristics, but the adhesive force is weak, resulting in dropping of the active material, which in turn reduces the life of the battery.
이러한 문제점을 고려한 것으로서 미국 특허 US 5,380,606호에는 전극의 바인더로서, 폴리아믹 애시드(polyamic acid)와, 폴리아마이드 레진(polyamide resin), 폴리비닐 피롤리돈(polyvinylpyrrolidone) 그리고 하이드록시알킬셀룰로오즈(hydroxyalkylcellulose)로 된 그룹으로부터 선택된 적어도 하나의 폴리머를 포함하는 혼합 바인더를 제안하여, 전지의 수명과 신뢰성을 향상시키고 있다.In consideration of this problem, US Pat. No. 5,380,606 discloses a binder of an electrode as polyamic acid, polyamide resin, polyvinylpyrrolidone and hydroxyalkylcellulose. It is proposed a mixed binder containing at least one polymer selected from the group selected to improve the life and reliability of the battery.
그러나 상기한 혼합 바인더는 극판의 건조 공정시 추가된 폴리아믹 액시드를 제거하기 위해 200 내지 400℃에서 고온 열처리를 해야 하기 때문에, 공정의 운영이 복잡하고 어려우며, 열처리시 전극의 물성이 변화하는 문제점이 있다.However, the above-mentioned mixed binder has to be subjected to high temperature heat treatment at 200 to 400 ° C. in order to remove the polyamic acid added during the drying process of the electrode plate, so that the operation of the process is complicated and difficult, and the physical properties of the electrode change during the heat treatment. There is this.
반면 이차전지의 전극 제조에 사용하는 것으로 접착력이 강한 바인더로는 스틸렌 부타디엔 러버(SBR)가 있다. 이것은 접착력이 강하지만 전극을 구성할 경우 압연율이 낮아 스프링백 현상이 발생하게 되며, 그로 인하여 전극 충, 방전시의 부피 팽창에 의해 활물질의 탈락이 발생하므로 전지의 수명을 단축하게 된다.On the other hand, styrene butadiene rubber (SBR) is used as a binder having strong adhesive strength, which is used for manufacturing an electrode of a secondary battery. This adhesive strength is strong, but when the electrode is composed of a low rolling rate springback phenomenon occurs, thereby reducing the life of the battery due to the drop off of the active material by volume expansion during electrode charging, discharging.
한편, 카복시메틸 셀룰로오스(sodium Carboxymethyl cellulose, 이하 ‘CMC'라고 칭한다.)는 물에 잘 용해 또는 잘 분산되고, 전기 화학적인 안정성, 유기 용매에 대한 비용해성, 접착력 등의 조건을 충족하는 친환경 바인더로서 알려져 있다. Meanwhile, carboxymethyl cellulose (hereinafter referred to as 'CMC') is an environmentally friendly binder that dissolves or disperses well in water and satisfies conditions such as electrochemical stability, insolubility to organic solvents, and adhesion. Known.
그러나 상기 CMC는 현재 일본과 미국 등에서 개발되어 있으며, 대부분의 세계시장을 차지하고 있으며, 이에 국내 시장에서는 전량 수입에 의존하고 있다.However, the CMC is currently developed in Japan, the United States, etc., occupies most of the world market, and thus the domestic market relies on total imports.
이에, 본 발명자들은 전기 화학적으로 안정하며, 전지 내 유기용매에 녹지 않고, 활물질을 기재에 잘 붙일 수 있는 접착력을 갖는 특정한 조합으로 이루어진 바인더 및 이의 제조방법을 발견하고, 본 발명을 완성하였다.Accordingly, the present inventors have found a binder and a method for producing the same, which are electrochemically stable and have a bonding force capable of adhering an active material to a substrate without being dissolved in an organic solvent in a battery, thereby completing the present invention.
상술한 종래 기술의 문제점을 해결하기 위한 것으로서, 본 발명은 전극합제 내 도전제의 분산을 증가시키고 전극의 전해액 흡습을 증가시켜, 완성된 전지의 초기용량, 사이클 특성 등과 같은 전지 특성을 향상시킬 수 있는 새로운 조성비의 전극 합제용 CMC를 제공하고자 한다.In order to solve the above problems of the prior art, the present invention can increase the dispersion of the conductive agent in the electrode mixture and increase the electrolyte absorption of the electrode, thereby improving the battery characteristics such as initial capacity, cycle characteristics, etc. of the finished battery To provide a new composition ratio of the electrode mixture CMC.
본 발명은 상기 전극 합제용 CMC를 포함하여 제조되는 것을 특징으로 하는 이차전지용 전극을 제공하고자 한다.The present invention is to provide a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC.
이러한 목적을 달성하기 위한 본 발명은 전극합제 내 도전제의 분산을 증가시키고 전극의 전해액 흡습을 증가시켜, 완성된 전지의 초기용량, 사이클 특성 등과 같은 전지 특성을 향상시킬 수 있는 새로운 조성비의 전극 합제용 CMC의 제조방법을 제공한다.The present invention for achieving this purpose is to increase the dispersion of the conductive agent in the electrode mixture and to increase the electrolyte absorption of the electrode, the electrode composition of a new composition ratio that can improve the battery characteristics such as initial capacity, cycle characteristics of the finished battery It provides a method for producing a CMC.
본 발명은 상기 방법으로 제조된 중량평균분자량(Mw) 800,000 내지 900,000인 전극 합제용 CMC를 제공한다.The present invention provides a CMC for electrode mixture having a weight average molecular weight (Mw) 800,000 to 900,000 prepared by the above method.
본 발명은 상기 전극 합제용 CMC를 포함하여 제조되는 것을 특징으로 하는 이차전지용 전극을 제공한다.The present invention provides a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC.
본 발명에 따른 바인더는, 이차전지의 전극 합제용 바인더로서, 중량평균분자량(Mw) 800,000 내지 900,000인 것을 특징으로 한다.The binder according to the present invention is characterized in that the weight average molecular weight (Mw) 800,000 to 900,000 as a binder for electrode mixture of the secondary battery.
본 발명에 따른 바인더는, 이차전지의 전극 합제용 바인더로서, 치환도가 1 내지 2, 수용액 1 중량%일 때의 점도가 250 내지 300 cps, ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 한다.The binder according to the present invention is a binder for electrode mixture of a secondary battery, the viscosity is 250 to 300 cps when the substitution degree is 1 to 2, 1% by weight of an aqueous solution, the content of metal ions measured by ICP analysis is 150 to 250 ppm.
이하, 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail.
본 발명에 따른 전극 합제용 CMC는 중량평균분자량(Mw)이 1,000,000 내지 5,000,000인 천연셀룰로오스 1 내지 40 중량%, IPA(isopropanol) 및 에탄올 혼합 알코올 10 내지 80중량%, 수산화나트륨(NaOH) 1 내지 30 중량%, 클로로아세트산(MCA) 1 내지 30 중량%를 포함하는 전극 합제용 CMC 조성물을 제공한다.CMC for electrode mixture according to the present invention has a weight average molecular weight (Mw) of 1,000,000 to 5,000,000 natural cellulose 1 to 40% by weight, IPA (isopropanol) and ethanol mixed alcohol 10 to 80% by weight, sodium hydroxide (NaOH) 1 to 30 It provides a CMC composition for electrode mixture comprising a weight%, 1 to 30% by weight chloroacetic acid (MCA).
본 발명에 있어서 상기 천연셀룰로오스는 면 섬유 펄프 및 우드펄프의 혼합펄프를 사용할 수 있으며, 상기 면 섬유 펄프 및 우드펄프의 혼합비는 중량비로, 상기 중량비는 1:1인 것이 바람직하나 이에 한정되는 것은 아니다. In the present invention, the natural cellulose may be a mixed pulp of cotton fiber pulp and wood pulp, the mixing ratio of the cotton fiber pulp and wood pulp is a weight ratio, the weight ratio is preferably 1: 1, but is not limited thereto. .
본 발명에 따른 전극 합제용 CMC는 천연셀룰로오스 1 내지 40 중량%, 바람직하게는 10 내지 30 중량％이다. 만약 1 중량% 미만일 경우에는, 활성 물질 표면의 피복 상태가 불충분하고 활성 물질 표면과 전해액과의 접촉 면적이 넓어 전지의 안전성이 떨어진다. 또한, 중합체의 전극 및 집전체의 접착성이나 전극 활물질 사이의 결착성이 저하되고, 반복 첫 방전에서의 방전 용량이 저하되는 문제가 있다.The CMC for electrode mixture according to the present invention is 1 to 40% by weight of natural cellulose, preferably 10 to 30% by weight. If it is less than 1% by weight, the coating state of the surface of the active material is insufficient, and the contact area between the surface of the active material and the electrolyte is wide, resulting in poor battery safety. Moreover, there exists a problem that the adhesiveness of the electrode of a polymer and an electrical power collector, or binding property between electrode active materials falls, and the discharge capacity in a repetitive first discharge falls.
또한, 만약 40 중량%를 초과하는 경우에는, 전극 표면에 형성되는 피막이 지나치게 두껍게 되고, 전극 활물질과 전해액 계면에서의 리튬 이온 투과성이 떨어져, 내부 저항이 증대하여 첫 방전 용량이 저하되는 문제가 있다.In addition, if it exceeds 40% by weight, the film formed on the surface of the electrode becomes too thick, the lithium ion permeability at the interface between the electrode active material and the electrolyte is poor, the internal resistance increases, and there is a problem that the first discharge capacity is lowered.
본 발명은 The present invention
1) IPA(isopropanol) 및 에탄올 혼합물 10 내지 80 중량%에 수산화나트륨(NaOH) 1 내지 30 중량%를 첨가하여 혼합액을 제조하는 단계;1) preparing a mixed solution by adding 1 to 30% by weight of sodium hydroxide (NaOH) to 10 to 80% by weight of an IPA (isopropanol) and ethanol mixture;
2) 상기 혼합액에 중량평균분자량(Mw)이 1,000,000 내지 5,000,000인 천연셀룰로오스 1 내지 40 중량%를 첨가하여 알카리성 셀룰로오스를 제조하는 단계;2) preparing an alkaline cellulose by adding 1 to 40% by weight of the natural cellulose having a weight average molecular weight (Mw) of 1,000,000 to 5,000,000 to the mixed solution;
3) 상기 알카리성 셀룰로오스에 클로로아세트산(MCA) 1 내지 30 중량%를 첨가하여 반응물을 제조하는 단계;3) preparing a reactant by adding 1 to 30% by weight of chloroacetic acid (MCA) to the alkaline cellulose;
4) 상기 반응물을 에탄올에 희석된 염산 또는 질산용액을 가하여 중화시키는 단계;4) neutralizing the reaction by adding hydrochloric acid or nitric acid solution diluted in ethanol;
5) 상기 중화된 반응물을 세척하여 여과하는 단계; 및5) washing and filtering the neutralized reactants; And
6) 상기 여과된 반응물을 건조하여 CMC(sodium Carboxymethyl cellulose)를 수득하는 단계;6) drying the filtered reaction to obtain sodium carboxymethyl cellulose (CMC);
를 포함하는 중량평균분자량(Mw) 800,000 내지 900,000인 전극 합제용 CMC의 제조방법을 제공한다.It provides a weight average molecular weight (Mw) comprising 800,000 to 900,000 of the method for producing a CMC electrode mixture comprising a.
본 발명은 상기 제조방법으로 제조된 CMC(sodium Carboxymethyl cellulose)로서, 중량평균분자량(Mw) 800,000 내지 900,000, 치환도가 1 내지 2, 수용액 1 중량%일 때의 점도가 250 내지 300 cps, ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 하는 전극 합제용 CMC를 제공한다.The present invention is a CMC (sodium carboxymethyl cellulose) prepared by the above method, the weight average molecular weight (Mw) of 800,000 to 900,000, when the substitution degree of 1 to 2, the aqueous solution of 1% by weight of 250 to 300 cps, ICP analysis It provides a CMC for electrode mixture, characterized in that the content of the metal ion is measured by 150 to 250 ppm.
본 발명에 따른 천연셀룰로오스는 중량평균분자량(Mw)이 1,000,000 내지 5,000,000인 것을 사용할 수 있으며, 보다 바람직하게는 2,500,000 내지 3,500,000인 것을 사용할 수 있다.Natural cellulose according to the present invention can be used that the weight average molecular weight (Mw) is 1,000,000 to 5,000,000, more preferably 2,500,000 to 3,500,000 can be used.
상기 천연셀룰로오스의 중량평균분자량(Mw)이 1,000,000 미만이면 제조되는 이차전지의 전극 합제용 바인더에서 전해액성 및 탄성력을 발휘하기 어려워 접착력 저하 및 충방전 효율 감소를 일으키고, 5,000,000을 초과하게 되면 전해액과의 높은 친화성으로 인한 과량의 전해액의 흡수, 팽윤에 의해 집전체로부터 전극의 탈리를 유발할 수 있으므로 바람직하지 않다.When the weight average molecular weight (Mw) of the natural cellulose is less than 1,000,000, it is difficult to exert the electrolytic solution and elastic force in the electrode mixture binder of the secondary battery produced, resulting in a decrease in adhesive strength and a charge and discharge efficiency, and when exceeded 5,000,000, Absorption and swelling of excess electrolyte due to high affinity may cause detachment of the electrode from the current collector, which is not preferable.
본 발명에 있어서, 상기 1) 단계의 수산화나트륨 농도는 50%인 것을 특징으로 한다.In the present invention, the sodium hydroxide concentration of step 1) is characterized in that 50%.
본 발명에 있어서, 상기 3) 단계의 클로로아세트산 농도는 30%인 것을 특징으로 한다.In the present invention, the chloroacetic acid concentration of step 3) is characterized in that 30%.
보다 상세하게는 CMC의 수산화나트륨 농도는 50%, 및 모노클로로아세트산(MCA) 농도 30%의 조건일 때 머서화 및 에테르화 반응에 완전히 일어나 물에 잘 용해 또는 분산도 증가되고, 대조구인 CMC(HB-45: 일본 다이치 제품)와 유사한 값을 나타내어, 전극 합제용 바인더로써 본연의 기능을 수행할 수 있음을 확인할 수 있었다.More specifically, when the sodium hydroxide concentration of CMC is 50%, and monochloroacetic acid (MCA) concentration is 30%, mercuryization and etherification reactions occur completely to increase the solubility or dispersion in water, and the control CMC ( HB-45 (manufactured by Daichi, Japan), similar values were found, and it was confirmed that the original function could be performed as a binder for electrode mixture.
본 발명에 있어서, 상기 4) 단계의 염산, 질산 또는 킬레이트제는 반응물의 중화 뿐 아니라 금속의 반응성을 이용하여 제조된 CMC 내 존재하는 금속불순물의 제거와 고순도의 CMC 수득에 중요한 의미를 가진다.In the present invention, the hydrochloric acid, nitric acid or chelating agent of step 4) has an important meaning for the removal of metal impurities present in the CMC prepared by using the reactivity of the metal as well as the neutralization of the reactants and obtaining a high purity CMC.
상기 킬레이트제는 EDTA(ethylenediaminetetraacetic acid)를 사용할 수 있으며, 바람직하게는 EDTA-2Na, EDTA-3Na 또는 EDTA-4Na으로부터 선택되는 하나 이상 사용할 수 있으나, 이에 한정되는 것은 아니다.The chelating agent may use ethylenediaminetetraacetic acid (EDTA), preferably one or more selected from EDTA-2Na, EDTA-3Na or EDTA-4Na, but is not limited thereto.
일 예로, Zn이 포함되어 있는 CMC를 물에 희석한 에탄올에 분산시킨 후, 금속 지시약과 함께 EDTA-4Na 및 구연산을 1 내지 20 중량%를 혼합하여 반응시킬 경우, Zn 금속이온은 금속 지시약에서 의해 분리되고, EDTA-4Na 또는 구연산과 결합하여 Zn 불순물을 추출할 수 있다.For example, when the CMC containing Zn is dispersed in ethanol diluted in water, and then reacted by mixing 1 to 20% by weight of EDTA-4Na and citric acid together with the metal indicator, the Zn metal ion is separated from the metal indicator. It can be separated and combined with EDTA-4Na or citric acid to extract Zn impurities.
다시 말해, 이차전지용 CMC 내 금속성분이 포함될 경우, 전지 성능 뿐 아니라 전지수명을 단축시키는 중대한 문제를 발생하게 함으로 금속성분을 최소화 시켜야 전지성능을 발현시키는데, 본 발명에 따른 상기 4) 단계는 본 발명의 중요한 의미를 가진다.In other words, when the metal component in the secondary battery CMC is included, the battery performance must be minimized by generating a serious problem that shortens the battery life as well as the battery performance to express the battery performance, the step 4) according to the present invention Has an important meaning.
[반응식 1]Scheme 1
Ca+2+ 2HCl → CaCl₂ + H2 ↑Ca +2 + 2HCl → CaCl₂ + H 2 ↑
2Fe+3 + 6HCl → 2FeCl3 + 3H2 ↑2Fe +3 + 6HCl → 2FeCl 3 + 3H 2 ↑
CuO + 2HNO3 => Cu(NO3)2 + H2OCuO + 2HNO3 => Cu (NO 3 ) 2 + H2O
Cu + 4HNO3 => Cu(NO3)2 + 2H2O + 2NO2 Cu + 4HNO 3 => Cu (NO 3 ) 2 + 2H 2 O + 2NO 2
[반응식 2]Scheme 2
Zn + In(금속 지시약) → Zn-InZn + In (metal indicator) → Zn-In
Zn-In + EDTA → Zn-EDTA(킬레이트화 된 물질) + In(금속 지시약)Zn-In + EDTA → Zn-EDTA (chelated material) + In (metal indicator)
본 발명에 있어서, 상기 CMC는 상기의 방법에 제조됨으로써 ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 한다.In the present invention, the CMC is produced by the above method, characterized in that the content of metal ions measured by ICP analysis is 150 to 250 ppm.
본 발명에 있어서, 상기 CMC는 상기의 방법에 제조됨으로써 치환도가 1 내지 1.5이고, 수용액 1 중량%일 때의 점도가 250 내지 300 cps인 것을 특징으로 한다.In the present invention, the CMC is prepared by the above method, the degree of substitution is 1 to 1.5, characterized in that the viscosity when the aqueous solution 1% by weight is 250 to 300 cps.
CMC는 수용성 이지만 다른 수용성 고분자와 같이 용해과정에서 팽윤되어 서서히 용해된다.CMC is water soluble, but like other water soluble polymers, it swells during dissolution and dissolves slowly.
상기 본 발명에 따른 CMC의 치환도가 1 미만 또는 수용액 1 중량%일 때의 점도가 250 cps 미만이면, 무기물 입자의 표면에 바인더가 결합하기 어렵고, 치환도가 1.5 초과 또는 수용액 1 중량%일 때의 점도가 300 cps를 초과하는 경우에는 친수성 유기 용매에 용해되어 불균일한 반응이 발생되거나 바인더의 점도를 부여하여 극판의 제조 시 강도를 유지시키는 등의 바인더 본연의 기능을 수행하기 힘들어 바람직하지 않다.When the degree of substitution of the CMC according to the present invention has a viscosity of less than 1 or 1% by weight of an aqueous solution of less than 250 cps, it is difficult for a binder to bind to the surface of the inorganic particles, and when the degree of substitution is more than 1.5 or 1% by weight of an aqueous solution. When the viscosity exceeds 300 cps, dissolution in a hydrophilic organic solvent occurs, which causes uneven reactions or imparts a viscosity of the binder to maintain the strength during manufacture of the electrode plate, which is not preferable.
또한 본 발명은 상기 방법으로 제조된 전극 합제용 CMC(sodium Carboxymethyl cellulose)를 포함하여 제조되는 것을 특징으로 하는 이차전지용 전극을 제공한다.In another aspect, the present invention provides a secondary battery electrode, characterized in that prepared by the electrode mixture prepared by the CMC (sodium Carboxymethyl cellulose).
보다 상세하게는 중량평균분자량(Mw) 800,000 내지 900,000, 치환도가 1 내지 2, 수용액 1 중량%일 때의 점도가 250 내지 300 cps, ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 하는 전극 합제용 CMC를 포함하여 제조되는 것을 특징으로 하는 이차전지용 전극을 제공한다.More specifically, when the weight average molecular weight (Mw) 800,000 to 900,000, the substitution degree of 1 to 2, the aqueous solution of 1% by weight of 250 to 300 cps, the content of metal ions measured by ICP analysis is 150 to 250 ppm It provides a secondary battery electrode, characterized in that the manufacturing including the electrode mixture CMC characterized in that.
이차전지용 전극은 전극 활물질과 바인더 및 선택적으로 도전제, 충진제 등을 혼합한 전극 합제를 집전체에 코팅하여 제조된다. 구체적으로, 전극 합제를 소정의 용매에 첨가하여 전극 슬러리를 제조한 후 이를 금속 호일 등의 집전체 상에 도포하고 건조 및 압연하여 소정의 시트형 전극을 제조할 수 있다.The secondary battery electrode is manufactured by coating an electrode mixture, in which an electrode active material, a binder, and optionally a conductive agent, a filler, and the like are mixed with a current collector. Specifically, the electrode mixture may be added to a predetermined solvent to prepare an electrode slurry, and then coated on a current collector such as a metal foil, dried, and rolled to prepare a predetermined sheet-shaped electrode.
상기 바인더는 음극 및/또는 양극의 바인더로서 모두 사용가능하며, 음극의 바인더로서 더욱 바람직하게 사용될 수 있다. 특히, 높은 용량을 가지지만 충방전시 부피 변화가 큰 실리콘계 활물질, 주석계 활물질, 실리콘-탄소계 활물질 등을 음극 활물질로서 사용하는 경우에 바람직한 바인더일 수 있다.The binder can be used both as a binder of the negative electrode and / or a positive electrode, more preferably used as a binder of the negative electrode. In particular, a binder having a high capacity but having a large volume change during charging and discharging may be a preferred binder when a silicon-based active material, a tin-based active material, a silicon-carbon-based active material, or the like is used as the negative electrode active material.
상기 실리콘 또는 주석계 음극 활물질은 실리콘(Si) 입자, 주석(Sn) 입자, 실리콘-주석 합금, 이들 각각의 합금 입자, 복합체 등을 포함하는 의미이다. 상기 합금의 대표적인 예로는 실리콘 원소에 알루미늄(Al), 망간(Mn), 철(Fe), 티타늄(Ti) 등의 고용체, 금속간 화합물, 공정합금 등을 들 수 있지만, 이들만으로 한정 되는 것은 아니다. The silicon or tin-based negative active material is meant to include silicon (Si) particles, tin (Sn) particles, silicon-tin alloys, their respective alloy particles, composites, and the like. Typical examples of the alloy include, but are not limited to, solid solutions such as aluminum (Al), manganese (Mn), iron (Fe), titanium (Ti), intermetallic compounds, eutectic alloys, and the like. .
상기 바인더는 전극 합제 전체 중량을 기준으로 대략 1 내지 50 중량%, 바람직하게는 2 내지 20 중량%로 포함될 수 있다. 바인더의 함량이 너무 적으면 충방전시 발생하는 부피 변화를 견딜 수 있는 바인더로서의 역할을 기대하기 어렵고, 반대로 바인더의 함량이 너무 많으면 전극의 용량 감소 및 저항 증가를 유발하므로 바람직하지 않다.The binder may be included in about 1 to 50% by weight, preferably 2 to 20% by weight based on the total weight of the electrode mixture. If the content of the binder is too small, it is difficult to expect a role as a binder capable of withstanding the volume change generated during charging and discharging. On the contrary, the content of the binder is too high because it causes a decrease in the electrode capacity and an increase in resistance.
상기 전극 슬러리의 제조시 사용되는 용매의 바람직한 예로는 디메틸셀폭사이드(dimethyl sulfoxide, DMSO), N-메틸피리돈(N-methyl pyrrolidon, NMP) 등을 들 수 있으며, 이러한 용매는 전극 합제 전체 중량을 기준으로 400 중량%까지 사용할 수 있고 건조 과정에서 제거된다.Preferred examples of the solvent used in the preparation of the electrode slurry include dimethyl sulfoxide (DMSO), N-methyl pyrrolidon (NMP), and the like. It can be used up to 400% by weight and is removed during the drying process.
앞서 설명한 바와 같은 전극 합제에는 전극 활물질과 본 발명의 바인더 이외에, 점도 조절제, 도전제, 충진제, 커플링제, 접착 촉진제 등의 기타의 성분들이 선택적으로 또는 둘 이상의 조합으로서 더 포함될 수 있다.In addition to the electrode active material and the binder of the present invention, the electrode mixture as described above may further include other components, such as a viscosity modifier, a conductive agent, a filler, a coupling agent, an adhesion promoter, or a combination of two or more thereof.
상기 점도 조절제는 전극 합제의 혼합 공정과 그것의 집전체 상의 도포 공정이 용이할 수 있도록 전극 합제의 점도를 조절하는 성분으로서, 이러한 점도 조절제의 예로는, 폴리비닐리덴 플로라이드 등이 있지만, 이들만으로 한정되는 것은 아니다. 경우에 따라서는, 앞서 설명한 용매가 점도 조절제로서의 역할을 병행할 수 있다.The viscosity modifier is a component that adjusts the viscosity of the electrode mixture so that the mixing process of the electrode mixture and the coating process on the current collector thereof can be facilitated. Examples of such viscosity regulators include polyvinylidene fluoride, It is not limited. In some cases, the solvent described above can serve as a viscosity modifier.
상기 도전제는 전극 활물질의 도전성을 더욱 향상시키기 위한 성분으로서, 이러한 도전제는 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 천연 흑연이나 인조 흑연 등의 흑연; 카본블랙, 아세틸렌 블랙, 케첸 블랙, 채널 블랙, 퍼네이스 블랙, 램프 블랙, 서머 블랙 등의 카본블랙; 탄소 섬유나 금속섬유 등의 도전성 섬유; 불화 카본, 알루미늄, 니켈 분말 등의 금속 분말; 산화아연, 티탄산 칼륨 등의 도전성위스키; 산화티탄 등의 도전성 금속 산화물; 폴리페닐렌 유도체 등의 도전성 소재 등이 사용될 수 있다.The conductive agent is a component for further improving the conductivity of the electrode active material, and the conductive agent is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, natural graphite or artificial graphite may be used. Graphite; Carbon blacks such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fibers and metal fibers; Metal powders such as carbon fluoride powder, aluminum powder and nickel powder; Conductive whiskeys 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.
상기 충진제는 전극의 팽창을 억제하는 보조성분으로서, 당해 전지에 화학적 변화를 유발하지 않으면서 섬유상 재료라면 특별히 제한되는 것은 아니며, 예를 들어, 폴리에틸렌, 폴리프로필렌 등의 올레핀계 중합체; 유리섬유, 탄소섬유 등의 섬유상 물질이 사용된다.The filler is an auxiliary component that suppresses the expansion of the electrode, and is not particularly limited as long as it is a fibrous material without causing chemical changes in the battery. Examples of the filler include olefin polymers such as polyethylene and polypropylene; Fibrous materials, such as glass fiber and carbon fiber, are used.
상기 커플링제는 활물질과 바인더 사이의 접착력을 증가시키기 위한 보조성분으로서, 두 개 이상의 관능기를 가지고 있는 것을 특징으로 하며, 이러한 커플링제는, 예를 들어, 하나의 관능기가 실리콘, 주석, 또는 흑연계 활물질 표면의 히드록실기나 카르복실기와 반응하여 화학적인 결합을 형성하고, 다른 관능기가 고분자 바인더와의 반응을 통하여 화학결합을 형성하는 물질일 수 있다. 커플링제의 구체적인 예로는, 트리에톡시실일프로필 테트라셀파이드(triethoxysilylpropyl tetrasulfide), 멀캡토프로필 트리에톡시실란(mercaptopropyl triethoxysilane), 아미노프로필 트리에톡시실란(aminopropyl triethoxysilane), 클로로프로필 트리에톡시실란(chloropropyl triethoxysilane), 비닐 트리에톡시실란(vinyl triethoxysilane), 메타아크릴옥시프로필 트리에톡시실란(methacryloxypropyl triethoxysilane), 글리시독시프로필 트리에톡시실란(glycidoxypropyl triethoxysilane), 이소시안아토프로필 트리에톡시실란(isocyanatopropyl triethoxysilane), 시안아토프로필 트리에톡시실란(cyanatopropyl triethoxysilane) 등의 실란계 커플링제를 들 수 있지만, 이들만으로 한정되는 것은 아니다.The coupling agent is an auxiliary component for increasing the adhesion between the active material and the binder, characterized in that it has two or more functional groups, such a coupling agent, for example, one functional group is silicon, tin, or graphite It may be a material that reacts with a hydroxyl group or a carboxyl group on the surface of the active material to form a chemical bond, and other functional groups form a chemical bond through a reaction with the polymer binder. Specific examples of the coupling agent include triethoxysilylpropyl tetrasulfide, mercaptopropyl triethoxysilane, aminopropyl triethoxysilane, and chloropropyl triethoxysilane ( chloropropyl triethoxysilane, vinyl triethoxysilane, methacryloxypropyl triethoxysilane, glycidoxypropyl triethoxysilane, isocyanatepropyl triethoxysilane (isocyanatopropyl Silane coupling agents, such as triethoxysilane) and cyanatopropyl triethoxysilane, are mentioned, but it is not limited to these.
상기 접착 촉진제는 집전체에 대한 음극 활물질의 접착력을 향상시키기 위해 첨가되는 보조성분으로서, 예를 들어 옥살산(oxalic acid), 아디프산(adipic acid), 포름산(formic acid), 아크릴산(acrylic acid) 유도체, 이타콘산(itaconic acid) 유도체 등을 들 수 있다.The adhesion promoter is an auxiliary component added to improve the adhesion of the negative electrode active material to the current collector, for example oxalic acid, adipic acid, formic acid, acrylic acid Derivatives, itaconic acid derivatives, and the like.
본 발명에 따른 전극에서 집전체는 활물질의 전기화학적 반응에서 전자의 이동이 일어나는 부위로서, 음극 집전체와 양극 집전체가 존재한다.In the electrode according to the present invention, a current collector is a site where electrons move in an electrochemical reaction of an active material, and a negative electrode current collector and a positive electrode current collector exist.
상기 음극 집전체는 일반적으로 3 내지 500 ㎛의 두께로 만들어진다. 이러한 음극 집전체는, 당해 전지에 화학적 변화를 유발하지 않으면서 도전성을 가진 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 구리, 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 구리나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면처리한 것, 알루미늄-카드뮴 합금 등이 사용될 수 있다.The negative electrode current collector is generally made to a thickness of 3 to 500 ㎛. Such a negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change in the battery. For example, the surface of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel Surface-treated with carbon, nickel, titanium, silver, and the like, aluminum-cadmium alloy, and the like can be used.
상기 양극 집전체는 일반적으로 3 내지 500 ㎛의 두께로 만든다. 이러한 양극 집전체는, 당해 전지에 화학적 변화를 유발하지 않으면서 높은 도전성을 가지는 것이라면 특별히 제한되는 것은 아니며, 예를 들어, 스테인리스 스틸, 알루미늄, 니켈, 티탄, 소성 탄소, 또는 알루미늄이나 스테인리스 스틸의 표면에 카본, 니켈, 티탄, 은 등으로 표면처리 한 것 등이 사용될 수 있다.The positive electrode current collector is generally made to a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, the surface of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel Surface treated with carbon, nickel, titanium, silver, or the like may be used.
이들 집전체들은 그것의 표면에 미세한 요철을 형성하여 전극 활물질의 결합력을 강화시킬 수도 있으며, 필름, 시트, 호일, 네트, 다공질체, 발포체, 부직포체 등 다양한 형태로 사용될 수 있다.These current collectors may form fine concavities and convexities on the surface thereof to enhance the bonding strength of the electrode active material, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.
상기 전극 활물질 중 음극 활물질로는 탄소계 물질, 실리콘계 물질, 주석계 물질, 실리콘-탄소계 물질 등이 사용될 수 있으며, 양극 활물질로는 리튬 코발트 산화물(LiCoO2), 리튬 니켈 산화물(LiNiO2) 등의 층상 화합물이나 1 또는 그 이상의 전이금속으로 치환된 화합물; 화학식 Li1+xMn2-xO4(여기서, x 는 0 ~ 0.33 임), LiMnO3, LiMn2O3, LiMnO2 등의 리튬 망간 산화물; 리튬 동 산화물(Li2CuO2); LiV3O8, LiFe3O4, V2O5, Cu2V2O7 등의 바나듐 산화물; 화학식 LiNi1-xMxO2(여기서, M = Co, Mn, Al, Cu, Fe, Mg, B 또는 Ga 이고, x = 0.01 ~ 0.3임)으로 표현되는 Ni 사이트형 리튬 니켈 산화물; 화학식 LiMn2-xMxO2(여기서, M = Co, Ni, Fe, Cr, Zn 또는 Ta이고, x = 0.01 ~ 0.1 임) 또는 Li2Mn3MO8(여기서, M = Fe, Co, Ni, Cu 또는 Zn 임)로 표현되는 리튬 망간 복합 산화물; 화학식의 Li 일부가 알칼리토금속 이온으로 치환된 LiMn2O4 디설파이드 화합물; Fe2(MoO4)3 등이 사용될 수 있다.Among the electrode active materials, a carbon-based material, a silicon-based material, a tin-based material, and a silicon-carbon-based material may be used as the negative electrode active material, and the positive electrode active material may be lithium cobalt oxide (LiCoO 2 ), lithium nickel oxide (LiNiO 2 ), or the like. Layered compounds of or compounds substituted with one or more transition metals; 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 ); LiV 3 O 8, LiFe 3 O 4, V 2 O 5, vanadium oxide such as Cu 2 V 2 O 7; Ni-site type lithium nickel oxide represented by the formula LiNi 1-x M x O 2 , wherein 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 , wherein M = Co, Ni, Fe, Cr, Zn or Ta, and x = 0.01 to 0.1, or Li 2 Mn 3 MO 8, where M = Fe, Co, Ni , Lithium manganese composite oxide represented by Cu or Zn); LiMn 2 O 4 disulfide compounds in which a part of Li in the formula is substituted with alkaline earth metal ions; Fe 2 (MoO 4 ) 3 and the like can be used.
본 발명에 따른 CMC를 전극 합제의 바인더로 사용함으로써, 특히 충·방전 시 음극 활물질들의 큰 부피 변화에도 불구하고 활물질 상호간 및 집전체와의 결합력이 안정적으로 유지될 수 있으며 활물질의 부피팽창에 따른 균열을 최소화 시키므로 고용량의 실리콘 또는 주석계 음극 활물질의 상용화를 가능케 하여 대용량 리튬 이차전지의 제조에 크게 기여할 수 있다.By using the CMC according to the present invention as a binder of the electrode mixture, the bonding strength between the active materials and the current collector can be stably maintained despite the large volume change of the negative electrode active materials during charging and discharging, and cracks due to the volume expansion of the active materials Since it can minimize the commercialization of a high capacity silicon or tin-based negative electrode active material can greatly contribute to the production of large capacity lithium secondary battery.
도 1은 본 발명에 따른 CMC(sodium Carboxymethyl cellulose)를 포함하여 제조된 전극의 C-rate 비율을 조사한 그래프이고,1 is a graph illustrating a C-rate ratio of an electrode manufactured by using sodium carboxymethyl cellulose (CMC) according to the present invention.
(A: 제조예의 CMC 이용, B: 대조구의 CMC(HB-45: 일본 다이치 제품)이용)(A: Use of CMC of Preparation Example, B: Use of CMC (HB-45: manufactured by Daiichi Japan) of Control)
도 2는 본 발명에 따른 CMC(sodium Carboxymethyl cellulose)를 포함하여 제조된 전극의 초기 사이클과 500 사이클 진행 후의 방전 용량 회복율을 조사한 그래프이며,2 is a graph showing the discharge capacity recovery rate after the initial cycle and 500 cycles of the electrode prepared by including the sodium carboxymethyl cellulose (CMC) according to the present invention,
(Cell-G: 제조예의 CMC 이용, Cell-N: 대조구의 CMC(HB-45: 일본 다이치 제품)이용)(Cell-G: using CMC of preparation example, Cell-N: using CMC of control (HB-45: Daiichi Japan))
도 3은 본 발명에 따른 CMC(sodium Carboxymethyl cellulose)를 포함하여 제조된 전극의 박리강도를 조사한 그래프이다.Figure 3 is a graph of the peel strength of the electrode prepared including the CMC (sodium Carboxymethyl cellulose) according to the present invention.
본 발명은 하기 실시예에 의하여 더욱 구체적으로 설명한다. 그러나, 하기 실시예는 본 발명의 이해를 돕기 위한 것일 뿐, 어떤 의미로든 본 발명의 범위가 이러한 실시예에 의하여 한정되는 것은 아니다.The invention is explained in more detail by the following examples. However, the following examples are only intended to help the understanding of the present invention, and the scope of the present invention in any sense is not limited by these examples.
이때, 사용되는 기술 용어 및 과학 용어에 있어서 다른 정의가 없다면, 이 발명이 속하는 기술 분야에서 통상의 지식을 가진 자가 통상적으로 이해하고 있는 의미를 가지며, 하기의 설명 및 첨부 도면에서 본 발명의 요지를 불필요하게 흐릴 수 있는 공지 기능 및 구성에 대한 설명은 생략한다.At this time, if there is no other definition in the technical terms and scientific terms used, it has a meaning commonly understood by those of ordinary skill in the art to which the present invention belongs, the gist of the present invention in the following description and the accompanying drawings Descriptions of well-known functions and configurations that may be unnecessarily blurred are omitted.
[제조예 1] 고순도 CMC의 제조방법 Preparation Example 1 Manufacturing Method of High Purity CMC
중량평균분자량(Mw)이 3,000,000면 섬유펄프와 소프트우드 펄프(soft wood pulp;캐나다 kamloops 산)를 1:1 중량비로 혼합한 셀룰로오스에 50% NaOH 수용액, 15중량%, IPA(isopropanol) 및 에탄올 혼합 알코올 54 중량%를 첨가하여 니더교반기(고점도 교반기)에 투입하여 37℃를 유지하면서 1h 동안 교반하여 머서화 반응을 시켰다.50% NaOH aqueous solution, 15% by weight, IPA (isopropanol) and ethanol in cellulose mixed with 3,000,000 cotton fiber pulp and softwood pulp (Canada kamloops acid) in a weight ratio of 1,000,000 cotton by weight average molecular weight (Mw) 54% by weight of alcohol was added to the kneader stirrer (high viscosity stirrer), followed by stirring for 1 h while maintaining 37 ° C. for mercerization reaction.
상기 머서화 반응이 끝난 후 30% 모노클로로아세트산(MCA) 수용액을 첨가하여 항온조건에서 에테르화 반응을 진행하고, 상기 에테르화 반응이 끝난 반응물을 에탄올에 의해 희석된 30% 염산용액으로 중화시켰다. 상기 중화된 반응물을 에탄올과 물의 혼합 정제액을 이용하여 3회 세척하여, Filtering 후 수득된 반응물을 최종적으로 에탄올로 세척하여 건조(80℃/1h)하여 CMC 분말을 수득하였다.After completion of the mercerization reaction, 30% monochloroacetic acid (MCA) aqueous solution was added to proceed with etherification at constant temperature, and the etherification reaction was neutralized with 30% hydrochloric acid diluted with ethanol. The neutralized reactant was washed three times with a mixture of ethanol and water, and the resulting reaction was filtered and finally washed with ethanol and dried (80 ° C./1 h) to obtain CMC powder.
[제조예 2] 고순도 CMC의 제조방법 Preparation Example 2 Manufacturing Method of High Purity CMC
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 에테르화 반응이 끝난 반응물을 에탄올에 의해 희석된 30% EDTA 용액으로 중화시켰다.To prepare a CMC powder in the same manner as in Preparation Example 1, the reaction after the etherification was neutralized with a 30% EDTA solution diluted with ethanol.
[비교 제조예 1]Comparative Preparation Example 1
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 에테르화 반응시 5% 모노클로로아세트산(MCA) 수용액을 이용하였다.To prepare a CMC powder in the same manner as in Preparation Example 1, 5% monochloroacetic acid (MCA) aqueous solution was used in the etherification reaction.
[비교 제조예 2]Comparative Preparation Example 2
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 에테르화 반응시 15% 모노클로로아세트산(MCA) 수용액을 이용하였다.To prepare a CMC powder in the same manner as in Preparation Example 1, 15% monochloroacetic acid (MCA) aqueous solution was used in the etherification reaction.
[비교 제조예 3]Comparative Production Example 3
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 에테르화 반응시 25% 모노클로로아세트산(MCA) 수용액을 이용하였다.To prepare a CMC powder in the same manner as in Preparation Example 1, 25% monochloroacetic acid (MCA) aqueous solution was used during the etherification reaction.
[비교 제조예 4]Comparative Production Example 4
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 머서화 반응시 40% NaOH 수용액을 첨가하고, 에테르화 반응시 30% 모노클로로아세트산(MCA) 수용액을 이용하였다.To prepare a CMC powder in the same manner as in Preparation Example 1, 40% NaOH aqueous solution was added during mercerization, and 30% monochloroacetic acid (MCA) aqueous solution was used during etherification.
[비교 제조예 5]Comparative Production Example 5
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 머서화 반응시 45% NaOH 수용액을 첨가하고, 에테르화 반응시 30% 모노클로로아세트산(MCA) 수용액을 이용하였다.A CMC powder was prepared in the same manner as in Preparation Example 1, except that 45% NaOH aqueous solution was added during mercerization, and 30% monochloroacetic acid (MCA) aqueous solution was used during etherification.
[비교 제조예 6]Comparative Production Example 6
상기 제조예 1과 동일한 방법으로 CMC 분말을 제조하되, 머서화 반응시 55% NaOH 수용액을 첨가하고, 에테르화 반응시 30% 모노클로로아세트산(MCA) 수용액을 이용하였다.To prepare a CMC powder in the same manner as in Preparation Example 1, 55% NaOH aqueous solution was added during mercerization, and 30% monochloroacetic acid (MCA) aqueous solution was used during etherification.
[시험예 1] CMC의 치환도 측정Test Example 1 Measurement of Substitution Degree of CMC
상기 제조예의 CMC와 상기 비교 제조예 1 내지 6의 CMC의 치환도(Degree of Substitution; DS) 측정하였다. 대조구로 CMC(HB-45: 일본 다이치 제품)을 사용하였다. 상기 치환도는 Green의 방법(J. W., cellulose Ether, In method in carbohydrate chemistry, whistler, R. L., Vol. 3, Academic press, New York, 1963, pp.322)을 이용하였다.Degree of Substitution (DS) of CMC of Preparation Example and CMC of Comparative Preparation Examples 1 to 6 was measured. CMC (HB-45: manufactured by Daiichi Japan) was used as a control. The degree of substitution used Green's method (J. W., cellulose Ether, In method in carbohydrate chemistry, whistler, R. L., Vol. 3, Academic press, New York, 1963, pp. 322).
[식 1][Equation 1]
Figure PCTKR2013007947-appb-I000001
Figure PCTKR2013007947-appb-I000001
(S는 CMC의 건조질량(g), C는 HCl 표준용액의 부피(ml), N은 HCl용액의 노르말농도, f는 HCl 표준용액의 보정계수이다.(S is the dry mass of CMC (g), C is the volume of HCl standard solution (ml), N is the normal concentration of HCl solution, f is the correction coefficient of HCl standard solution).
표 1
치환도 용해도(%)
대조구 1.0 99
제조예 1 1.1 99
제조예 2 1.15 99
비교제조예 1 0.39 60
비교제조예 2 0.7 75
비교제조예 3 0.78 82
비교제조예 4 0.5 63
비교제조예 5 0.67 74
비교제조예 6 0.65 67
Table 1
Degree of substitution Solubility (%)
Control 1.0 99
Preparation Example 1 1.1 99
Preparation Example 2 1.15 99
Comparative Production Example 1 0.39 60
Comparative Production Example 2 0.7 75
Comparative Production Example 3 0.78 82
Comparative Production Example 4 0.5 63
Comparative Production Example 5 0.67 74
Comparative Production Example 6 0.65 67
상기 표 1의 결과로부터 본 발명에 따른 제조예 CMC의 수산화나트륨 농도는 50%, 및 모노클로로아세트산(MCA) 농도 30%의 조건일 때 머서화 및 에테르화 반응에 완전히 일어나 물에 잘 용해 또는 분산도 증가되고, 대조구인 CMC(HB-45: 일본 다이치 제품)와 유사한 값을 나타내어, 전극 합제용 바인더로써 본연의 기능을 수행할 수 있음을 확인할 수 있었다.From the results of Table 1, sodium hydroxide concentration of Preparation Example CMC according to the present invention was completely dissolved in water and dispersed in water due to mercerization and etherification reactions under conditions of 50% and monochloroacetic acid (MCA) concentration of 30%. Also increased, showing a similar value to the control CMC (HB-45: manufactured by Daichi Japan), it was confirmed that the original function can be performed as a binder for electrode mixture.
[시험예 2] CMC의 점도측정(Viscosity : Brookfield Viscometer)Test Example 2 Viscosity Measurement of CMC (Viscosity: Brookfield Viscometer)
상기 제조예의 CMC와 상기 비교 제조예 1 내지 6의 CMC의 점도를 측정하였다. 상기 점도는 하기의 방법으로 브룩필드 점도계(Brookfield Viscometer)를 이용하여 측정하였다. 대조구로 CMC(HB-45: 일본 다이치 제품)을 사용하였다.The viscosity of the CMC of Preparation Example and CMC of Comparative Preparation Examples 1 to 6 was measured. The viscosity was measured using a Brookfield Viscometer in the following manner. CMC (HB-45: manufactured by Daiichi Japan) was used as a control.
증류수 294 g에 상기 제조예 및 비교제조예의 각각의 CMC 분말 6 g을 용해시켜 2%의 용액을 제조하였다.A solution of 2% was prepared by dissolving 6 g of each CMC powder of Preparation Example and Comparative Preparation Example in 294 g of distilled water.
400 ml 비이커에 증류수를 담고 상기 제조된 용액을 소량씩 첨가하면서 4,000 rpm 에서 4분간 고속교반 후, 항온조에서 20분간 보관하여 기포를 제거하고 spindle을 정확히 취하여 브룩필드 점도계(Brookfield Viscometer)로 점도를 측정하였다. 이때, CMC 용액의 온도는 25℃로 정한다.Add distilled water to a 400 ml beaker and add a small amount of the prepared solution at a high speed of stirring for 4 minutes at 4,000 rpm, and then store it in a thermostat for 20 minutes to remove bubbles and take the spindle accurately and measure the viscosity with a Brookfield Viscometer. It was. At this time, the temperature of the CMC solution is set to 25 ℃.
표 2
점도
대조구 275
제조예 1 270
제조예 2 273
비교제조예 1 210
비교제조예 2 241
비교제조예 3 257
비교제조예 4 219
비교제조예 5 245
비교제조예 6 232
TABLE 2
Viscosity
Control 275
Preparation Example 1 270
Preparation Example 2 273
Comparative Production Example 1 210
Comparative Production Example 2 241
Comparative Production Example 3 257
Comparative Production Example 4 219
Comparative Production Example 5 245
Comparative Production Example 6 232
상기 표 2의 결과로부터 본 발명에 따른 제조예의 CMC의 경우 수용액 1 중량%일 때의 점도가 270 cps 이상의 값으로, 대조구인 CMC(HB-45: 일본 다이치 제품)와 유사한 값을 나타내었으나, 비교 제조예의 경우 점도가 245 cps 이하의 점도를 나타내는 것을 확인할 수 있었다.From the results of Table 2, in the case of the CMC of the preparation example according to the present invention, the viscosity at 1% by weight of the aqueous solution was 270 cps or more, which was similar to that of the control CMC (HB-45: manufactured by Daiichi Japan). In the case of the production example, it was confirmed that the viscosity shows a viscosity of 245 cps or less.
상기의 결과는 본 발명의 CMC가 전극 합제용 바인더로써 제조되는 전지의 수명 특성을 유지 또는 상승시킬 수 있음을 확인한 결과이기도 하다.The above result is also a result confirming that the CMC of the present invention can maintain or increase the lifespan characteristics of a battery manufactured as a binder for electrode mixture.
[시험예 3] CMC의 금속성분 함유량 조사Test Example 3 Investigation of Metal Component Content of CMC
상기 제조예의 CMC와 상기 비교 제조예 1 내지 6의 CMC의 금속성분 함유량 조사하였다. 상기 금속성분 함유량은 유도결합 플라즈마 (ICP) 분석에 의하여 측정하였다. 대조구로 CMC(HB-45: 일본 다이치 제품)을 사용하였다.The metal component content of CMC of the said manufacture example and CMC of the comparative manufacture examples 1-6 was investigated. The metal content was measured by inductively coupled plasma (ICP) analysis. CMC (HB-45: manufactured by Daiichi Japan) was used as a control.
표 3
금속불순물 총량 ppm(Fe, Al, Ca, Mg)
대조구 150
제조예 1 200
제조예 2 165
비교제조예 1 450
비교제조예 2 420
비교제조예 3 250
비교제조예 4 425
비교제조예 5 350
비교제조예 6 325
TABLE 3
Total amount of metal impurity ppm (Fe, Al, Ca, Mg)
Control 150
Preparation Example 1 200
Preparation Example 2 165
Comparative Production Example 1 450
Comparative Production Example 2 420
Comparative Production Example 3 250
Comparative Production Example 4 425
Comparative Production Example 5 350
Comparative Production Example 6 325
상기 표 3의 결과로부터 본 발명에 따른 제조예의 CMC의 경우 ICP 분석에 의하여 측정되는 금속 이온(Fe, Al, Ca, Mg)의 함량이 200 ppm 이하로서, 대조구인 CMC(HB-45: 일본 다이치 제품)와 유사한 값을 나타내었으나, 비교 제조예의 경우 350 ppm 이상의 금속 불순물을 함유하고 있음을 확인할 수 있었다.In the case of CMC of Preparation Example according to the present invention from the results of Table 3, the content of metal ions (Fe, Al, Ca, Mg) measured by ICP analysis is 200 ppm or less, and the control CMC (HB-45: Daiichi Japan). Product)), but in the case of Comparative Preparation Example it could be confirmed that it contains more than 350 ppm metal impurities.
상기의 결과는 본 발명의 CMC가 전극 합제용 바인더로써 제조되는 전지의 특성을 향상시키고, 전지의 수명 특성을 유지 또는 상승시킬 수 있음을 확인한 결과이기도 하다.The above result is also a result of confirming that the CMC of the present invention can improve the characteristics of a battery produced as a binder for electrode mixture and maintain or increase the lifespan characteristics of the battery.
[시험예 4] [Test Example 4]
상기 제조예 중 물성이 가장 양호하게 평가된 제조예 2의 CMC와 상기 비교 제조예 중 물성이 가장 양호하게 평가된 비교 제조예 3의 CMC를 선택하였고, 상기 선별된 CMC를 포함하여 통상의 전지 제조방법으로 전지를 제조하였다. 대조구로 CMC(HB-45: 일본 다이치 제품)을 사용하였다.The CMC of Preparation Example 2 having the best evaluated physical properties among the Preparation Examples and the CMC of Comparative Preparation Example 3 having the best evaluated physical properties among the Comparative Preparation Examples were selected, and the conventional battery was prepared including the selected CMC. The battery was manufactured by the method. CMC (HB-45: manufactured by Daiichi Japan) was used as a control.
C-rate별 방전용량을 측정하고, 이를 백분율로 환산하여 방전효율을 계산하였다. 이때, 상기 방전효율을 계산하는 것은 기준 방전용량인 최초 방전용량(0.2C 방전용량) 대비 C-rate별 방전용량을 대비하여 계산하였으며, 상기 C-rate별 방전용량은 기준 방전 용량인 0.2C , 0.5C, 1.0C, 2C 방전용량, 0.2C 대비 2C 방전용량을 측정하였다.The discharge capacity for each C-rate was measured, and the discharge efficiency was calculated by converting it into a percentage. In this case, the discharge efficiency was calculated by comparing the discharge capacity for each C-rate with respect to the initial discharge capacity (0.2C discharge capacity), which is the standard discharge capacity, and the discharge capacity for each C-rate is 0.2C, the reference discharge capacity. 0.5C, 1.0C, 2C discharge capacity, 2C discharge capacity compared to 0.2C was measured.
표 4
구분 대조구 제조예 2 비교제조예 3
0.2C 방전용량(mAH/g) 1332.23 1331.86 1330.25
방전효율(%) 100 100 100
0.2C 대비0.5C 방전 방전용량(mAH/g) 1321.19 1321.69 1290.17
방전효율(%) 99.17 99.24 96.98
0.2C 대비1.0C 방전 방전용량(mAH/g) 1320.15 1321.14 1141.03
방전효율(%) 99.09 99.20 85.76
0.2C 대비2.0C 방전 방전용량(mAH/g) 1302.80 1306.60 1107.21
방전효율(%) 97.79 98.10 83.23
Table 4
division Control Preparation Example 2 Comparative Production Example 3
0.2C Discharge capacity (mAH / g) 1332.23 1331.86 1330.25
Discharge efficiency (%) 100 100 100
0.5C discharge compared to 0.2C Discharge capacity (mAH / g) 1321.19 1321.69 1290.17
Discharge efficiency (%) 99.17 99.24 96.98
1.0C discharge compared to 0.2C Discharge capacity (mAH / g) 1320.15 1321.14 1141.03
Discharge efficiency (%) 99.09 99.20 85.76
2.0C discharge compared to 0.2C Discharge capacity (mAH / g) 1302.80 1306.60 1107.21
Discharge efficiency (%) 97.79 98.10 83.23
이때, 충전이나 방전의 전류치를 나타내는데 0.2C, 0.5C, 1.0C 2.0C 등의 표현을 사용하고 있다. 당업계에서 1C는 전지의 정격 용량과 같은 전류로 충전 또는 방전하는 것을 의미하는 것으로, 0.1C는 전지의 정격 용량의 1/10의 전류가 충전 또는 방전되고 있다는 것을 의미한다.At this time, expressions such as 0.2C, 0.5C, 1.0C and 2.0C are used to indicate the current values of charging and discharging. In the art, 1C means charging or discharging with a current equal to a battery's rated capacity, and 0.1C means that one tenth of the battery's rated capacity is being charged or discharged.
예를 들어, 전지의 정격 용량이 1000mAh의 이차 전지를 1000mAh의 전류로 충전 또는 방전할 때, 이를 1C 충전 또는 1C 방전이라고 하며, 이때, 1시간 만에 충전 또는 방전이 종료한다고 가정한다.For example, when a secondary battery having a rated capacity of 1000 mAh is charged or discharged at a current of 1000 mAh, this is called 1C charging or 1C discharge, and it is assumed that charging or discharging ends in 1 hour.
이때, 만일 상기 전지의 정격 용량이 1000mAh의 이차 전지를 2000mAh의 전류로 충전 또는 방전할 때, 이를 2C 충전 또는 2C 방전이라고 하며, 이때는 30분만에 충전 또는 방전이 종료되게 된다.In this case, if the secondary battery having a rated capacity of 1000 mAh is charged or discharged with a current of 2000 mAh, this is called 2C charging or 2C discharge, in which case charging or discharging is completed in 30 minutes.
또한, 상기 전지의 정격 용량이 1000mAh의 이차 전지를 500mAh의 전류치로 충전 또는 방전할 때, 0.5C 충전 또는 0.5C 방전이라고 하며, 이때는 2 시간만에 충전시와 같이 셀을 소정 시간에 소정 전류로 충전 또는 방전하는 것을 나타내기 위하여 씨-레이트(C-rate)라는 개념을 사용한다.In addition, when the secondary battery having a rated capacity of 1000 mAh is charged or discharged at a current value of 500 mAh, it is referred to as 0.5C charging or 0.5C discharge. The concept of C-rate is used to indicate charging or discharging.
이는 동일한 시간에 충전 또는 방전되는 전류의 용량이 서로 상이함을 의미하며, 따라서, 상기 씨-레이트(Crate)란 간단히 말해 시간당 전류 용량률로 정의하기도 한다.This means that the capacities of the currents charged or discharged at the same time are different from each other. Thus, the C-rate may be simply defined as the current capacity ratio per hour.
즉, 본 발명에서 예를 들어, 0.2C 대비 0.5C 방전용량이라 함은 0.5C로 방전하는 경우의 방전용량을 의미하며, 0.2C 대비 0.5C 방전효율이라 함은 0.2C로 방전하는 경우와 0.5C로 방전하는 경우의 방전용량을 비교한 방전효율을 의미하는 것으로, 0.2C로 방전하는 경우보다 0.5C로 방전하는 경우가 더 큰 전류로 방전이 이루어져, 더 빠른 시간에 방전이 완료됨을 의미하며, 결국, 동일한 시간 내에 방전되는 전류의 용량이 0.5C의 경우가 큼을 의미한다.That is, in the present invention, for example, 0.5C discharge capacity compared to 0.2C means the discharge capacity when discharged at 0.5C, 0.5C discharge efficiency compared to 0.2C is 0.5 when discharged at 0.2C It means the discharge efficiency compared with the discharge capacity when discharged at C. When discharged at 0.5C than discharged at 0.2C, the discharge is performed with a larger current, which means that the discharge is completed at a faster time. In other words, it means that the capacity of the current discharged within the same time is larger than 0.5C.
상기 표 4의 결과로부터 확인할 수 있듯이, 최초 충방전 효율에 있어서는 제조예 및 비교 제조예에서 큰 차이가 없음을 나타내고 있다.As can be seen from the results in Table 4, the initial charge and discharge efficiency shows that there is no significant difference in the production examples and the comparative production examples.
하지만, C-rate의 비율이 증가 할수록, 비교 제조예의 경우 방전효율이 제조예보다 떨어짐을 알 수 있고, 특히 0.2C 대비 2.0C 방전의 경우의 비교 제조예는 방전효율이 제조예보다 현저하게 떨어짐을 알 수 있다.However, as the ratio of C-rate increases, it can be seen that the discharge efficiency is lower than that of the comparative example in the case of the comparative manufacturing example, in particular, in the case of 2.0C discharge compared to 0.2C, the discharge efficiency is significantly lower than the manufacturing example. It can be seen.
이는 C-rate의 비율이 증가하여 더 큰 전류로 방전이 이루어질수록, 즉, 이차전지를 사용하는 전자기기 장치 등에서 동일한 시간 내에 전류의 소모량이 증가 할수록, 방전될 수 있는 전지의 용량이 감소됨을 의미한다.This means that as the ratio of C-rate increases to discharge with a larger current, that is, as the current consumption increases within the same time in an electronic device using a secondary battery, the capacity of a battery that can be discharged decreases. do.
[시험예 5] [Test Example 5]
상기 시험예 4에서 제조된 전지를 이용하여 충/방전시 수명(Cycle life)을 조사하였다.Using the battery prepared in Test Example 4 was investigated the life (Cycle life) during charging / discharging.
표 5
제조예 2 대조구 비교제조예 3
0.5C 1393.67 1398.41 1386.12
1C 1372.12 1377.64 1351.47
1C/0.5C 98.45 98.51 97.50
100 Cycle 용량유지율(%) 96.82% 97.36% 92.69%
150 Cycle 용량유지율(%) 95.56% 96.16% 87.98%
200 Cycle 용량유지율(%) 94.19% 94.68% 77.23%
100 Cycle 후 전극부피 팽창(%) 691 689 -(활물질 분리)
Table 5
Preparation Example 2 Control Comparative Production Example 3
0.5C 1393.67 1398.41 1386.12
1C 1372.12 1377.64 1351.47
1C / 0.5C 98.45 98.51 97.50
100 Cycle capacity retention rate (%) 96.82% 97.36% 92.69%
150 Cycle capacity retention rate (%) 95.56% 96.16% 87.98%
200 Cycle capacity retention rate (%) 94.19% 94.68% 77.23%
Expansion of electrode volume after 100 cycles (%) 691 689 -(Active material separation)
상기 표 5의 결과에서도 확인할 수 있듯이, 제조예의 전지의 경우 초기용량, 효율, 사이클 용량 유지율 측면에서 모두 우수한 것을 확인할 수 있었고, 대조구의 CMC를 이용한 전지와는 초기효율 및 초기 용량도 비슷하였고, 전지의 싸이클 특성도 유사한 것을 확인할 있었다.As can be seen from the results of Table 5, the battery of the production example was confirmed that all excellent in terms of initial capacity, efficiency, cycle capacity retention rate, the initial efficiency and initial capacity was similar to the battery using the CMC of the control, the battery It was confirmed that the cycle characteristics of the similar.
상기 결과는 상기 실시한 시험예 4의 C-rate의 비율 결과와 마찬가지로, 제조예의 CMC는 대조구의 CMC와 마찬가지로 전극 합제용 바인더로써 본연의 기능을 가지고 있음을 확인한 결과이다.The result is a result of confirming that the CMC of Preparation Example has the original function as a binder for electrode mixture similar to the C-rate ratio of Test Example 4 carried out as described above.
[시험예 6] [Test Example 6]
상기 시험예 5의 결과를 바탕으로, 제조예의 CMC와 대조구의 CMC(HB-45: 일본 다이치 제품)를 포함하여 제조된 전지의 전극 박리 시험을 실시하였다.Based on the result of the said Test Example 5, the electrode peel test of the battery manufactured including the CMC of a manufacture example and CMC of a control (HB-45: Daiichi Japan) was performed.
실험방법으로 핫 롤 라미네이트(80℃, 0.3 m/분, 0.3 MPa)로 접착 필름의 양면에 50 ㎛의 폴리이미드 필름을 접합시키고, 170℃에서 1시간 경화시켰다. 그 적층 경화물을 폭 10㎜로 절단하여 평가 샘플로 제작했다. T0Y0 BALWIN제 UTM-4-100형 텐실론을 이용하여 180도의 각도로 50㎜/분의 인장속도로 박리시켰을 때의 값을 구했다. 값은 2개의 샘플을 이용하였다.A 50 μm polyimide film was bonded to both sides of the adhesive film with a hot roll laminate (80 ° C., 0.3 m / min, 0.3 MPa) by an experimental method, and cured at 170 ° C. for 1 hour. The laminated cured material was cut into width 10mm, and it produced into the evaluation sample. The value at the time of peeling at a tensile speed of 50 mm / min at the angle of 180 degree using the UTM-4-100 type tensilon made from T0Y0 BALWIN was calculated | required. The values used two samples.
표 6
최대값 인장연신(tensile Extension)(mm) 박리강도(N/m)
제조예 2 Electrode-G1 0.55 12.34
Electrode-G2 0.58 12.00
대조구 Electrode-N1 0.60 12.80
Electrode-N2 0.61 12.50
Table 6
Tensile extension (mm) Peel Strength (N / m)
Preparation Example 2 Electrode-G1 0.55 12.34
Electrode-G2 0.58 12.00
Control Electrode-N1 0.60 12.80
Electrode-N2 0.61 12.50
상기 표 6의 결과에서도 확인할 수 있듯이, 제조예의 CMC는 대조구의 CMC와 마찬가지로 전극 합제용 바인더로써 본연의 기능을 가지고 있음을 확인할 수 있었다. As can be seen from the results of Table 6, it was confirmed that the CMC of the production example had a natural function as a binder for electrode mixture similarly to the CMC of the control.
상기의 결과들로부터 본 발명의 CMC는 기존 수입에 의존하던 바인더의 대체에 있어 품질의 신뢰성을 극복한 우수한 전극 합제용 바인더 특성을 가짐을 확인할 수 있다.From the above results it can be seen that the CMC of the present invention has excellent binder properties for electrode mixture that overcomes the reliability of the quality in the replacement of the binder depending on the existing imports.

Claims (9)

1) IPA(isopropanol) 및 에탄올 혼합물 10 내지 80 중량%에 수산화나트륨(NaOH) 1 내지 30 중량%를 첨가하여 혼합액을 제조하는 단계;1) preparing a mixed solution by adding 1 to 30% by weight of sodium hydroxide (NaOH) to 10 to 80% by weight of an IPA (isopropanol) and ethanol mixture;
2) 상기 혼합액에 중량평균분자량(Mw)이 1,000,000 내지 5,000,000인 천연셀룰로오스 1 내지 40 중량%를 첨가하여 알카리성 셀룰로오스를 제조하는 단계;2) preparing an alkaline cellulose by adding 1 to 40% by weight of the natural cellulose having a weight average molecular weight (Mw) of 1,000,000 to 5,000,000 to the mixed solution;
3) 상기 알카리성 셀룰로오스에 클로로아세트산(MCA) 1 내지 30 중량%를 첨가하여 반응물을 제조하는 단계;3) preparing a reactant by adding 1 to 30% by weight of chloroacetic acid (MCA) to the alkaline cellulose;
4) 상기 반응물을 에탄올에 희석된 염산, 질산, 또는 킬레이트제 용액을 가하여 중화시키는 단계;4) neutralizing the reaction by adding dilute hydrochloric acid, nitric acid, or chelating agent solution in ethanol;
5) 상기 중화된 반응물을 세척하여 여과하는 단계; 및5) washing and filtering the neutralized reactants; And
6) 상기 여과된 반응물을 건조하여 CMC(sodium Carboxymethyl cellulose)를 수득하는 단계;6) drying the filtered reaction to obtain sodium carboxymethyl cellulose (CMC);
를 포함하는 중량평균분자량(Mw) 800,000 내지 900,000인 전극 합제용 CMC의 제조방법.Weight average molecular weight (Mw) comprising 800,000 to 900,000 of the method for producing an electrode mixture CMC.
제1항에 있어서,The method of claim 1,
상기 천연셀룰로오스는 면 섬유 펄프 및 우드펄프의 혼합펄프인 것을 특징으로 하는 전극 합제용 CMC의 제조방법. The natural cellulose is a manufacturing method of the electrode mixture CMC, characterized in that the mixed pulp of cotton fiber pulp and wood pulp.
제1항에 있어서,The method of claim 1,
상기 1) 단계의 수산화나트륨 농도는 50%인 것을 특징으로 하는 전극 합제용 CMC의 제조방법.Sodium hydroxide concentration of step 1) is a method for producing a CMC electrode mixture, characterized in that 50%.
제1항에 있어서,The method of claim 1,
상기 3) 단계의 클로로아세트산 농도는 30%인 것을 특징으로 하는 전극 합제용 CMC의 제조방법.The chloroacetic acid concentration of step 3) is the manufacturing method of the electrode mixture CMC, characterized in that 30%.
제1항에 있어서,The method of claim 1,
상기 4) 단계의 킬레이트제는 EDTA(ethylenediaminetetraacetic acid)인 것을 특징으로 하는 전극 합제용 CMC의 제조방법.The chelating agent of step 4) is a manufacturing method of the electrode mixture CMC, characterized in that EDTA (ethylenediaminetetraacetic acid).
제1항에 있어서,The method of claim 1,
상기 CMC는 치환도가 1 내지 1.5이고, 수용액 1 중량%일 때의 점도가 250 내지 300 cps인 것을 특징으로 하는 전극 합제용 CMC의 제조방법.The CMC has a substitution degree of 1 to 1.5, when the aqueous solution of 1% by weight of the viscosity of the mixture is 250 to 300 cps manufacturing method of the electrode mixture CMC.
제1항에 있어서,The method of claim 1,
상기 CMC는 ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 하는 전극 합제용 CMC의 제조방법.The CMC is a method of producing a CMC for electrode mixture, characterized in that the content of metal ions measured by ICP analysis 150 to 250 ppm.
상기 제1항 내지 상기 제7항에서 선택되는 어느 한 항의 제조방법으로 제조된 CMC(sodium Carboxymethyl cellulose)로서,As CMC (sodium carboxymethyl cellulose) prepared by the method of any one selected from claim 1 to claim 7,
중량평균분자량(Mw) 800,000 내지 900,000, 치환도가 1 내지 2, 수용액 1 중량%일 때의 점도가 250 내지 300 cps, ICP 분석에 의하여 측정되는 금속 이온의 함량이 150 내지 250 ppm인 것을 특징으로 하는 전극 합제용 CMC.When the weight average molecular weight (Mw) of 800,000 to 900,000, the substitution degree of 1 to 2, the aqueous solution of 1% by weight of 250 to 300 cps, characterized in that the content of metal ions measured by ICP analysis 150 to 250 ppm CMC for electrode mixture.
상기 제8항에 따른 CMC(sodium Carboxymethyl cellulose)를 포함하여 제조되는 것을 특징으로 하는 이차전지용 전극.A secondary battery electrode, characterized in that the manufacturing comprising the CMC (sodium Carboxymethyl cellulose) according to claim 8.
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