KR101281170B1 - Electrode Ink for inkjet print, Electrode and Lithium battery prepared using the same - Google Patents

Abstract

The present invention is an electrode ink for inkjet printing comprising an electrode active material, a polar medium and a humectant, wherein the humectant comprises a polyol compound represented by the following formula (1), wherein the polyol compound is contained in an amount of about 10 to about the total weight of the electrode ink. Disclosed is an electrode ink for inkjet printing, characterized in that 40% by weight.

≪ Formula 1 >

Wherein R ₁ to R ₅ and n refer to the detailed description of the invention.

Inkjet printing, electrode ink

Description

Electrode ink for inkjet printing, electrode and lithium battery prepared using the same {Electrode Ink for inkjet print, Electrode and Lithium battery prepared using the same}

The present invention relates to an electrode ink for inkjet printing, an electrode and a lithium battery manufactured using the same, and more particularly, an ink ink for inkjet printing comprising a polyol compound, an electrode manufactured by printing the electrode ink by an inkjet method, and A lithium battery employing the above electrode.

Secondary batteries are widely used as a driving power source for portable electronic devices such as notebook computers and mobile phones. However, with the development of technology, a new field of application emerges, and a secondary battery having a form and performance distinguished from a conventional secondary battery is required.

For example, a secondary battery used as a power source for driving a portable electronic device, which is light in weight and high in functionality, is packaged in various forms in order to secure safety of the electronic device. Therefore, there is a need for a secondary battery that can be molded into various forms. Secondary batteries used as power sources for driving hybrid vehicles and / or electric vehicles should be high in power, small in size and light in weight. Since one large battery cannot achieve high output, small size and light weight of a battery, an assembled battery in which a plurality of batteries are connected in series is used. Therefore, one secondary battery constituting the assembled battery should be in the form of a thin film which is miniaturized and lightweight. Secondary batteries used as power sources for flexible displays must be thin, light and bendable.

As a method of manufacturing a secondary battery that satisfies the various needs, an inkjet printing method in which an electrode ink in which an electrode active material is dispersed is coated on a surface of a current collector instead of a conventional method of coating an electrode active material slurry on a surface of a current collector is proposed. . In the inkjet printing method, the electrode active material is coated on the surface of the current collector thinly, uniformly and evenly, and is inexpensively coated in a predetermined pattern.

The inkjet printing method is classified into a thermal spray method and a piezoelectric element method according to the driving method, but nozzle clogging is likely to occur due to particles dispersed in the ink because ink is discharged from a nozzle having a diameter of about 50 μm regardless of the driving method. Therefore, prevention of nozzle clogging is prioritized in order to stably discharge ink.

The nozzle clogging occurs when the dispersibility of the electrode ink is lowered to precipitate particles dispersed in the electrode ink, or when the medium is volatilized around the nozzle and the concentration of the electrode ink is too high around the nozzle. In order to prevent nozzle clogging, various electrode inks are studied.

Japanese Laid-Open Patent Publication No. 2006-172995 discloses an electrode ink in which the particle diameter of the electrode active material and the conductive material is limited to 1 µm or less. The ink has a reduced particle size of particles dispersed in the ink, thereby improving dispersibility of the ink.

Japanese Patent Laid-Open No. 2004-361516 discloses an electrode ink containing active material particles and a surfactant. The dispersibility of the active material particles is improved by the surfactant in the ink.

An electrode ink for inkjet printing, comprising an electrode active material, a polar medium, and a humectant, wherein the humectant comprises a polyol compound represented by Formula 1 below, wherein the content of the polyol compound is 10 to 40 wt% based on the total weight of the electrode ink Electrode ink for phosphorus inkjet printing is provided:

≪ Formula 1 >

Where

R ₁ to R ₅ are each independently hydrogen; An alkoxy group having 1 to 10 carbon atoms unsubstituted or substituted with halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic hydrocarbon rings having 5 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic heterocycles having 5 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 30 carbon atoms unsubstituted or substituted with halogen; C7-C20 alkylaryl group unsubstituted or substituted by halogen; An arylalkyl group having 7 to 20 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 30 carbon atoms unsubstituted or substituted with halogen; n is an integer of 0 to 10;

An electrode is provided by applying the ink by an inkjet method.

There is provided a lithium battery, wherein the electrode is employed.

Hereinafter, an electrode ink for an inkjet printer according to a preferred embodiment of the present invention will be described in more detail.

An electrode ink for inkjet printing according to an embodiment of the present invention is an electrode ink for inkjet printing including an electrode active material, a polar medium, and a humectant, wherein the humectant comprises a polyol compound represented by Formula 1 below, The content is 10 to 40% by weight based on the total weight of the electrode ink.

≪ Formula 1 >

Where

R ₁ to R ₅ are each independently hydrogen; An alkoxy group having 1 to 10 carbon atoms unsubstituted or substituted with halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic hydrocarbon rings having 5 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic heterocycles having 5 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 30 carbon atoms unsubstituted or substituted with halogen; C7-C20 alkylaryl group unsubstituted or substituted by halogen; An arylalkyl group having 7 to 20 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 30 carbon atoms unsubstituted or substituted with halogen; n is an integer of 0 to 10;

Preferably, the polyol compound of Formula 1 is a compound represented by the following Formula 2:

<Formula 2>

Wherein R ₁ , R ₂ , R ₄ , R ₅ and n are as defined above.

More preferably, the polyol compound of Formula 1 is a compound represented by the following Formula 3:

<Formula 3>

HOCH _2- [CH (OH)] _n -CH ₂ OH

Wherein n is an integer from 0 to 10.

According to another embodiment of the invention preferably the moisturizer in the electrode ink may comprise ethylene glycol, glycerol or mixtures thereof.

The electrode ink according to the embodiment of the present invention includes a polyol compound containing a hydroxyl group capable of forming a hydrogen bond with the polar medium as a moisturizing agent, so that the polarity of the polar medium is low. In addition, the electrode ink containing the polyol compound has a high dielectric constant, thereby improving dispersibility of electrode active material particles and the like dispersed in the ink. As such, when the polarity of the polar medium is lowered and the dispersibility of the dispersed particles is improved, the viscosity of the electrode ink is reduced to improve nozzle clogging. Therefore, the discharge characteristic of the electrode ink is improved. In addition, even if the electrode ink is stored for a long time, precipitation does not occur, so even if the electrode ink is printed for a long time, nozzle clogging does not occur.

When the content of the polyol compound in the electrode ink is less than 10% by weight, the moisturizing effect is insignificant, thereby increasing the volatility of the polar medium. As the volatility of the polar medium becomes high, the concentration of the electrode ink becomes thicker around the nozzle of the inkjet print, so that the viscosity of the ink is increased and the composition of the ink to which the nozzle is clogged or ejected becomes nonuniform. That is, the discharge characteristic of electrode ink falls. When the content of the polyol compound is more than 40% by weight, the dielectric constant of the electrode ink is lowered, so that the dispersibility of particles dispersed in the electrode ink is lowered. Aggregation may occur between the dispersed particles so that the aggregated particles may precipitate.

The dielectric constant and dispersibility of the electrode ink will be described in more detail below, but for the purpose of understanding the present invention, it is intended to limit the scope of the present invention. When oxide particles are dispersed in a predetermined medium, an electric double layer is formed on the surface of the dispersed particles by a surface charge generated on the surface of the dispersed particles and a dipole of a solvent. As the polarity of the medium increases, the thickness of the bilayer increases. Increasing the thickness of the bilayer increases the number of medium molecules moving with the dispersed particles, thereby preventing collisions between the dispersed particles. However, as the polarity of the medium decreases, the thickness of the electrical double layer decreases, increasing the likelihood that particles collide with each other by Van der Waals force or Brownian motion. Thus, the dispersed particles may agglomerate with each other to cause precipitation.

According to another embodiment of the present invention, in the inkjet printing electrode ink, the dielectric constant of the polyol compound of Chemical Formula 1 is preferably 35 or more at 25 ° C., more preferably 35 to 45. When the dielectric constant is less than 35, dispersed particles may aggregate with each other to cause precipitation. If the dielectric constant is 35 or more, it is not particularly limited. If the dielectric constant is more than 45, the moisturizing function is lowered, and thus a large amount of polyol compound must be added to perform a predetermined moisturizing function. For example, the dielectric constant of ethylene glycol is 37.7 at 25 ° C, and the dielectric constant of glycerol is 42.5 at 25 ° C.

If a polyol compound having a high dielectric constant value is used, the dielectric constant of the ink is increased and the electrical double layer on the surface of the dispersed particles is thickened. Therefore, the dispersibility of the oxide particles can be improved.

According to another embodiment of the invention it is preferred that water is included in the polar medium. Water is a polar solvent with low volatility and does not damage the nozzles of inkjet printers. Water may be included as a main component of the polar medium and polar organic solvents such as methanol, ethanol, butanol, propanol, isopropanol, isobutyl alcohol and N-methyl-2-pyrrolidone may be included as auxiliary components. The term main component means a component that accounts for at least 51% of the total weight of the polar medium, and the balance is an auxiliary component.

The content of the polar medium is preferably 50 to 90% by weight of the total weight of the ink, but is not necessarily limited to this range.

According to another embodiment of the present invention, it is preferable that a metal oxide containing lithium, a transition metal oxide not containing lithium, or a carbonaceous material is included in the electrode active material. Examples of the metal oxide containing lithium include Li-Co-based metal oxides such as LiCoO ₂ ; Li-Ni-based metal oxides such as LiNiO ₂ ; Li-Mn type metal oxides, such as LiMn ₂ O ₄ and LiMnO ₂ ; Li-Cr-based metal oxides such as Li ₂ Cr ₂ O ₇ and Li ₂ CrO ₄ ; Li-Fe-based metal oxides such as LiFeO ₂ ; Li-V-based metal oxides; Li ₄ Ti ₅ O ₁₂ is a Li-Ti based metal oxides such as. The transition metal oxide not containing lithium is a transition metal oxide such as SnO ₂ , In ₂ O ₃ , and Sb ₂ O ₃ . Carbon-based materials are graphite, hard carbon, acetylene black, carbon black and the like. The electrode active material is used as a positive electrode active material or a negative electrode active material depending on the purpose of use. Depending on whether the electrode active material is a positive electrode active material or a negative electrode active material, the electrode ink for inkjet printing including the electrode active material is a positive electrode ink or a negative electrode ink. According to another embodiment of the present invention, the volume average particle diameter of the electrode active material is Although it will not specifically limit, if it is a magnitude | size which provides the outstanding dispersibility of an ink, It is preferable that it is 50-120 nm. If the volume average particle size exceeds 120 nm, the dispersibility of the ink is lowered. If the volume average particle size is 50 nm or less, there is no substantial difference in the dispersibility of the ink.

The content of the electrode active material is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight based on the total weight of the electrode ink for inkjet printing, but is not necessarily limited to this range.

According to another embodiment of the present invention, a conductive agent, a binder, a dispersant, a lithium salt and / or a buffer may be additionally included in the ink.

Conductive agents can be used to improve the conductivity of the oxide particles. The conductive agent to be used is not particularly limited as long as it is within the range of achieving the object of the present invention. Examples of the conductive agent include acetylene black, carbon black, graphite, carbon fibers, carbon nanotubes or mixtures thereof. The content of the conductive agent is preferably 0.1 to 10% by weight, more preferably 0.1 to 3% by weight based on the total weight of the electrode ink, but is not necessarily limited to this range.

A binder can be used to impart a bonding force between the printed ink and the current collector. The binder to be used is not particularly limited as long as it is within the range of achieving the object of the present invention. Examples of the binder include polyvinyl alcohol, polyimide, ethylene-propylene-diene terpolymer, styrene-butadiene rubber, polyvinylidne fluoride (PVDF), polytetrafluoroethylene, tetrafluoroethylene-hexafluoro Low propylene copolymer, carboxymethyl cellulose (CMC), or a mixture thereof. The content of the binder is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight based on the total weight of the electrode ink, but is not necessarily limited to this range.

Buffers may be used to maintain the stability of the ink and to maintain the proper pH. The buffer to be used is not particularly limited as long as it is within the scope of achieving the object of the present invention. Examples of the buffer include amine buffers such as trimenylamine, triethanolamine, diethanolamine, ethanolamine; Sodium hydroxide; Ammonium hydroxide; Or mixtures thereof. The content of the buffer is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight based on the total weight of the electrode ink, but is not necessarily limited to this range.

Dispersants may be used to disperse the oxide particles and the conductive agent in the ink. The dispersant used is not particularly limited as long as it is within the range of achieving the object of the present invention. For example, a fatty acid salt, an alkyl dicarboxylic acid salt, an alkyl sulfate ester salt, a polyhydric acid ester salt, an alkyl naphthalene sulfate, an alkylbenzene sulfate, an alkyl naphthalene sulfate ester salt, an alkyl sulfone succinate salt, a naphthenate salt, an alkyl ether carboxyl Acid salts, acylated peptides, alpha olefin sulfates, N-acyl methyl taurine salts, alkyl ether sulfates, secondary polyalcohol ethoxy sulfates, polyoxyethylene alkyl permil ether sulfates, monogly sulfates, alkyl ether phosphate ester salts, alkyl phosphoric acid Ester salts, alkylamine salts, alkylpyridium salts, alkylimidazolium salts, fluoroacrylic acid polymers, silicone crab acrylic acid polymers, polyoxyethylene alkyl ethers, polyoxyethylene sterol ethers, linoline derivatives of polyoxyethylene, polyoxyethylene Polyoxypropylene copolymer, polyoxyethylene sorbitan fatty acid ester, monoglyceride fatty acid ester, Sucrose fatty acid ester, alkanolamide fatty acid, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, polyvinyl alcohol, polyvinyl cellulose resin, acrylic resin, butadiene resin, styrene-acrylic copolymer resin, polyester resin , Polyamide-based resins, polyurethane-based resins, alkylbetaines, alkylamine oxides, porpatidilcholine or mixtures thereof. The dispersant may be used in an appropriate amount as necessary.

Lithium salts can be used to improve the ion conductivity of the ink. The lithium salt to be used is not particularly limited as long as it is within the range of achieving the object of the present invention. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl _10, and the like.

The electrode ink according to one embodiment of the present invention is not particularly limited in viscosity, but is preferably 1 to 50 cps, more preferably 5 to 10 cps.

Since the electrode ink according to the embodiment of the present invention improves the dispersibility of the dispersed particles, the content of solids such as an electrode active material and a conductive agent included in the electrode ink may be increased as compared with the conventional electrode ink. Therefore, a relatively thick concentration of the electrode ink can be produced so that the electrode manufacturing efficiency can be improved. For example, a thicker electrode ink may reduce the number of prints required to form an active material layer of the same thickness on the current collector as compared to a thinner electrode ink.

Electrode ink for inkjet printing according to an embodiment of the present invention is added to the polar medium in an appropriate amount of an electrode active material, a moisturizer, a buffer, a conductive agent, a binder and the like, a ball mill (bead mill) or a ball mill (bead mill) It is prepared by dispersing the ink constituents, and the like by filtration with a filter.

Hereinafter will be described in more detail with respect to the polyol compound according to an embodiment of the present invention. Halogen in the formulas according to an embodiment of the present invention is fluorine, chlorine, bromine, iodine.

In the chemical formulas according to one embodiment of the present invention, an unsubstituted alkoxy group having 1 to 20 carbon atoms is represented by -OX ₁ , wherein X ₁ is an alkyl group. The definition of an alkyl group is the same as that of the alkyl group below. Specific examples of the alkoxy group include methoxy, ethoxy, phenyloxy, cyclohexyloxy, naphthyloxy, isopropyloxy, diphenyloxy and the like, and at least one hydrogen atom of the alkoxy group may be replaced with a halogen atom. Can be.

Specific examples of the unsubstituted alkyl group having 1 to 20 carbon atoms in the formula according to an embodiment of the present invention are methyl, ethyl, propyl, isobutyl, n-butyl, sec-butyl, pentyl, iso-amyl, hexyl, heptyl , Octyl, nonyl, dealkyl, dodecyl, and the like, and at least one hydrogen atom of the alkyl group may be substituted with a halogen atom.

In the chemical formulas according to one embodiment of the present invention, an unsubstituted aliphatic hydrocarbon ring having 5 to 20 carbon atoms does not necessarily have one ring, and may have a plurality of rings, and may include a double bond in the ring. Do. For example, a norbornene group, a cyclohexyl group, a cycloheptyl group, etc. can be mentioned, It is not limited to this, One or more hydrogen atoms of the said aliphatic hydrocarbon ring can be substituted by a halogen atom similarly to the alkyl group mentioned above.

Among the chemical formulas according to one embodiment of the present invention, an unsubstituted aliphatic heterocyclic ring having 5 to 20 carbon atoms may be substituted with one or more atoms in a hydrocarbon ring substituted with one or more atoms selected from the group consisting of oxygen, nitrogen and sulfur. Say. The aliphatic heterocycle does not necessarily have one ring, but may have a plurality of rings. For example, an oxetane group, an oxirane group, etc. may be mentioned, but it is not limited to this, One or more hydrogen atoms of the said aliphatic heterocycle can be substituted by a halogen atom similarly to the alkyl group mentioned above. .

An unsubstituted aryl group having 6 to 30 carbon atoms in the chemical formula according to one embodiment of the present invention means a carbocyclic aromatic system having 6 to 30 carbon atoms including at least one aromatic ring, wherein the at least one ring is mutually Or may be linked through a single bond or the like. At least one hydrogen atom of the aryl group may be substituted with a halogen atom as in the case of the alkyl group described above.

In the above formulae, examples of the substituted or unsubstituted aryl group having 6 to 30 carbon atoms include a phenyl group, a C ₁ -C ₁₀ alkylphenyl group (eg, ethylphenyl group), a halophenyl group (eg, o-, m- And p-fluorophenyl group, dichlorophenyl group), cyanophenyl group, dicyanophenyl group, trifluoromethoxyphenyl group, biphenyl group, halobiphenyl group, cyanobiphenyl group, C ₁ -C ₁₀ biphenyl group, C ₁ -C ₁₀ alkoxy Biphenyl group, o-, m-, and p-tolyl group, o-, m- and p-cumenyl group, mesityl group, phenoxyphenyl group, (α, α-dimethylbenzene) phenyl group, (N, N'-dimethyl ) amino group, a (N, N'- diphenyl) aminophenyl group, penta LES group, indenyl group, a naphthyl group, a halonaphthyl group (e.g., naphthyl), fluoro, C ₁ -C ₁₀ alkyl naphthyl group (e.g. for example, a methyl naphthyl group), C ₁ -C ₁₀ alkoxy-naphthyl group (e.g., methoxy-naphthyl groups), cyano naphthyl groups, anthracenyl groups, Az LES group, a heptyl group tare, acetoxy tilre naphthyl group, a phenacyl Nilyl group, fluorenyl group, anthraquinolyl group, methyl anthryl group, phenanthryl group, triphenylene group, pyrenyl group, chrysenyl group, ethyl-crisenyl group, pisenyl group, perrylenyl group, chloroperylenyl group, penta A phenyl group, pentaxenyl group, tetraphenylenyl group, hexaphenyl group, hexasenyl group, rubisenyl group, coronyl group, trinaphthylenyl group, heptaphenyl group, heptasenyl group, pyranthrenyl group, an ovarenyl group, etc. are mentioned. .

Unsubstituted alkylaryl group having 7 to 20 carbon atoms in the formula according to an embodiment of the present invention refers to a substituted aryl group in one of the hydrogen atoms of the alkyl group. For example, a benzyl group etc. can be mentioned, but it is not limited to this. At least one hydrogen atom of the alkylaryl group may be substituted with a halogen atom.

Unsubstituted arylalkyl group having 7 to 20 carbon atoms in the formula according to an embodiment of the present invention refers to a substituted alkyl group to one of the hydrogen atoms of the aryl group. For example, 4-tert-butylphenyl group, 4-ethylphenyl group, etc. are mentioned, but it is not limited to this. At least one hydrogen atom of the arylalkyl group may be substituted with a halogen atom.

Unsubstituted heteroaryl group having 2 to 30 carbon atoms in the formula according to an embodiment of the present invention consists of one or more aromatic rings containing at least one heteroatom selected from N, O, P or S and the remaining ring atom is C By system, the one or more aromatic rings may be fused to each other, or may be linked through a single bond or the like. At least one hydrogen atom of the heteroaryl group may be substituted with a halogen atom. Examples of the unsubstituted heteroaryl group having 2 to 30 carbon atoms in the formulas include pyrazolyl group, imidazolyl group, oxazolyl group, thiazolyl group, triazolyl group, tetrazolyl group, oxadizolyl group, and pyri A diyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, an indolyl group, a quinolinyl group, an isoquinolinyl group, etc. are mentioned.

Electrode according to another embodiment of the present invention is produced by the electrode ink is printed in an inkjet method. The inkjet method is a method in which electrode ink is printed onto a current collector as droplets from a nozzle of an inkjet print. Although the inkjet method includes a thermal drive method, a piezoelectric element method, and the like, it is preferable to use a piezoelectric element method from the viewpoint of thermal stability of the battery material. The positive electrode is manufactured when the positive electrode ink including the positive electrode active material is printed by the inkjet method, and the negative electrode is manufactured when the negative electrode ink including the negative electrode active material is printed by the inkjet method.

The method of printing the electrode ink by an inkjet method is not particularly limited. For example, an inkjet printer using an inkjet head can be connected to a commercially available computer, and predetermined patterns can be created on the current collector by legitimate software. The means for drying the electrode ink printed on the current collector is preferably 1 minute to 8 hours in a vacuum atmosphere of 20 to 200 ℃, but is not necessarily limited to this range. The current collector may be a known material. For example, it is an aluminum thin film, a stainless thin film, a copper thin film, a nickel thin film, etc.

In the lithium battery according to another embodiment of the present invention, an electrode manufactured by printing the electrode ink by an inkjet method is adopted. The lithium battery according to another embodiment of the present invention is not particularly limited in form, but is preferably a stacked type, and also a lithium primary battery, a lithium secondary battery, as well as a fuel cell. The method for producing a lithium battery is not particularly limited except for employing an electrode in which the electrode ink is printed and drawn in an inkjet method. For example, a positive electrode ink according to an embodiment of the present invention is printed on a predetermined current collector by an inkjet method, and dried to form a positive electrode. The negative electrode ink according to the embodiment of the present invention is printed and dried in an inkjet manner on a surface opposite to the surface where the positive electrode of the current collector is formed to form a negative electrode. Therefore, a bipolar electrode is produced.

An electrolyte layer having a predetermined thickness is formed on the layer of the anode and / or the cathode of the bipolar electrode and dried. In an inert atmosphere, a bipolar electrode having the electrolyte layer formed thereon is stacked to manufacture a battery laminate. An insulating sealing layer is formed on the battery stack and packed to complete lithium displacement.

Hereinafter, the present invention will be described in further detail with reference to preferred examples, but the present invention is not limited thereto.

Examples 1-5 and Comparative Examples 1-3: Production of Electrode Ink

A mixed solution was prepared by mixing a polar medium, a humectant, an electrode active material, a buffer, a conductive agent, and a binder in a predetermined amount. Specific contents of the electrode ink components are listed in Table 1 below. The mixed solution was placed in a paint shaker (RED DEVIL company / 5400-02) containing zirconia beads having a particle diameter of 0.3 μm and stirred for 2 hours. After stirring, the mixed solution was sequentially filtered using a PTFE (Polytetrafluoroehtylene) syringe filter having a pore size of 1 μm and 0.45 μm (Syringe filter, 1 μm and 0.45 μm of Whatman) to prepare an electrode ink.

TABLE 1

Constituent Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polar medium
Deionized water 60 57.1 49.6 75.6 57.1 60 79.6 46.1 ethanol 6.5 6 6.5 6.5 6 6.5 6.5 6 Moisturizer Ethylene glycol 29.6 31 38 12 0 0 8 42 Glycerol 0 0 0 0 31 0 0 0 Diethylene glycol 0 2 2 2 2 29.6 2 2 Electrode active material Li ₄ Ti ₅ O ₁₂ 3 3 3 3 3 3 3 3 Buffer Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Conductive agent Acetylene black 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 bookbinder Carboxy
Methylcellulose 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1

* The unit of the content of each component in Table 1 is [% by weight].

Examples 6-10 and Comparative Examples 4-6: Preparation of Electrode Printed by Inkjet Method

The electrode inks prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were printed on copper foil using an HP deskjet 5550 series inkjet printer to prepare the electrodes of Examples 6 to 10 and Comparative Examples 4 to 6, respectively. The electrodes of Example 6 and Comparative Example 4 are shown in FIGS. 1 and 2, respectively.

Experimental Example 1: Measurement of the volume average particle diameter of the particles dispersed in the electrode ink

The volume average particle diameters of the particles dispersed in the electrode inks prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were measured. The volume average particle diameter was measured by Horiba Co., Ltd. particle size analyzer (LA-910). The measurement results are shown in Table 2 below.

Experimental Example 2 Evaluation of Dispersibility (Storage Stability) of Electrode Ink

5 ml of the electrode inks prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were placed in a 10 ml vial and left at room temperature for 24 hours to determine visually whether precipitation occurred. The evaluation results are shown in Table 2 below. In Table 2, uniformity means that precipitation does not occur in the electrode ink and a uniform state is maintained, and precipitation means that the dispersed particles are aggregated to cause precipitation.

<Table 2>

Volume average particle diameter of the dispersed particles [nm] Dispersibility of Electrode Ink Example 1 90 Uniformity Example 2 95 Uniformity Example 3 105 Uniformity Example 4 90 Uniformity Example 5 95 Uniformity Comparative Example 1 150 Sedimentation Comparative Example 2 90 Uniformity Comparative Example 3 200 Sedimentation

As shown in Table 2, Examples 1 to 5, in which the polyol compound according to one embodiment of the present invention is included within a predetermined content range, have a volume average particle diameter of the dispersed particles in a range of 90 to 105 nm and good dispersibility. . Therefore, the electrode ink can be stored for a long time and nozzle clogging does not occur even after printing for a long time.

Comparative Example 1 in which the polyol compound according to the embodiment of the present invention is not used and Comparative Example 3 in which the polyol compound according to the embodiment of the present invention is out of a predetermined content range have a volume average particle diameter of 150 Dispersibility is low as more than nm, and precipitation occurs.

In Comparative Example 2, in which the polyol compound according to one embodiment of the present invention is included out of a predetermined content range, the volume average particle diameter of the dispersed particles is 90 nm, and the dispersibility is good. However, the content of the humectant is low, as shown in Table 3 below, the discharge performance of the electrode ink is poor.

Experimental Example 3 Evaluation of Discharge Performance of Electrode Ink

The surface conditions of the electrodes prepared in Examples 6 to 10 and Comparative Examples 1 to 3 were visually observed to evaluate the ejection performance of the ink. The evaluation results are shown in Table 2 below, FIGS. 1 and 2. Discharge performance evaluation is determined by the following criteria.

Good: The electrode ink discharged on the surface of the current collector is printed uniformly.

Poor: The electrode ink discharged on the surface of the current collector is unevenly printed.

Not available for evaluation: No electrode ink is discharged due to clogged nozzles

<Table 2>

Discharge performance of electrode ink Example 6 Good Example 7 Good Example 8 Good Example 9 Good Example 10 Good Comparative Example 4 Bad Comparative Example 5 Bad Comparative Example 6 Not rated

As shown in Table 3, the electrodes of Examples 6 to 10 manufactured using the electrode ink containing the polyol compound according to one embodiment of the present invention within a predetermined content range have good discharge performance of the electrode ink. The electrode of Example 6 is shown in FIG. As shown in Fig. 1, in Example 6, the electrode ink is uniformly printed on the current collector.

On the contrary, the electrodes of Comparative Examples 4 to 6 produced using the electrode inks of Comparative Examples 1 to 3 have poor discharge performance of electrode inks. The electrode prepared in Comparative Example 4 is shown in FIG. 2. As shown in FIG. 2, in Comparative Example 4, the electrode ink is unevenly printed on the current collector.

1 is a surface of an electrode prepared in Example 5 according to an embodiment of the present invention.

2 is a surface of an electrode prepared in Comparative Example 4 according to an embodiment of the present invention.

Claims (11)

An electrode ink for inkjet printing, comprising an electrode active material, a polar medium, and a humectant, wherein the humectant comprises a polyol compound represented by the following Formula 1, An ink ink for inkjet printing, wherein the content of the polyol compound is 10 to 40% by weight based on the total weight of the electrode ink: &Lt; Formula 1 >

Where R ₁ to R ₅ are each independently hydrogen; An alkoxy group having 1 to 10 carbon atoms unsubstituted or substituted with halogen; An alkyl group having 1 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic hydrocarbon rings having 5 to 20 carbon atoms unsubstituted or substituted with halogen; Aliphatic heterocycles having 5 to 20 carbon atoms unsubstituted or substituted with halogen; An aryl group having 6 to 30 carbon atoms unsubstituted or substituted with halogen; C7-C20 alkylaryl group unsubstituted or substituted by halogen; An arylalkyl group having 7 to 20 carbon atoms unsubstituted or substituted with halogen; Or a heteroaryl group having 2 to 30 carbon atoms unsubstituted or substituted with halogen; n is an integer of 0-10. The electrode ink of claim 1, wherein the polyol compound of Chemical Formula 1 is a compound represented by the following Chemical Formula 2: <Formula 2>

Where R ₁ , R ₂ , R ₄ , R ₅ and n are as defined in claim 1 above. The electrode ink of claim 1, wherein the polyol compound of Formula 1 is a compound represented by Formula 3 below: <Formula 3> HOCH _2- [CH (OH)] _n -CH ₂ OH Where n is an integer of 0-10. The electrode ink of claim 1, wherein the humectant comprises ethylene glycol, glycerol or a mixture thereof. The electrode ink of claim 1, wherein the dielectric constant of the polyol compound of Chemical Formula 1 is 35 to 45 at 25 ° C. The electrode ink of claim 1, wherein water is included in the polar medium. The electrode ink of claim 1, wherein a metal oxide containing lithium, a transition metal oxide containing no lithium, or a carbonaceous material is included in the electrode active material. The electrode ink for inkjet printing according to claim 1, wherein the volume average particle diameter of the electrode active material is 50 to 120 nm. The electrode ink of claim 1, wherein a conductive agent, a binder, or a buffer is additionally included in the ink. An electrode according to any one of claims 1 to 9, wherein the ink is printed and manufactured by an inkjet method. A lithium battery, wherein the electrode according to claim 10 is employed.

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