[1][Mutual citations and related applications;
[2]This application claims the benefit of priority based on party 12.10.2015 Korea Patent Application No. 10-2015-0176256 28.10.2016 and Now Korea Patent Application No. 10-2016-0142054, all described in the literature of the Korea Patent Application content of which is incorporated as a part hereof.
[3]
[Technology]
[4]
The present invention high loading electrodes can be formed in the electrode active material layer having a uniform thickness without collapse and crack generation during manufacture and, as a result, the battery can improve the performance characteristics conductive material dispersion, and relates it to a lithium secondary battery manufactured by using that of will be.
BACKGROUND
[5]
There is demand for secondary batteries as an energy source is rapidly increasing as the development of technology and the demand for mobile devices increases. The secondary battery has a high energy density and voltage, long cycle life, self-discharge rate are commercially available and widely used low-lithium secondary battery. Further, as a high-capacity lithium secondary cell electrode as this, there has been actively conducted research on methods for the preparation of a unit to a higher energy density per unit electrode volume increase the electrode density.
[6]
In general, a high-density electrode since the electrode active material particles having a size of several to several tens can ㎛ ㎛ formed by molding with a high-pressure press, the particles are deformed, the space is reduced between the particles, the electrolyte tends to decrease permeability.
[7]
To address this problem, it uses a conductive material having a strength with excellent electrical conductivity in the manufacture of electrodes. When using a conductive material, the electrode prepared by being distributed between the conductive material and the electrode active material compressed penetration of the electrolyte to maintain the fine pores between the active material particles easily, it can also reduce the resistance within the electrode with good conductivity. In particular, such a conductive material and the use of fiber-like carbon-based conductive recognition carbon nanotubes that can further reduce the electrode resistance is increased by forming the electrically conductive paths within the electrode.
[8]
A type of carbon nanotube in the fine carbon fiber is a carbon tube having a diameter of less than 1㎛ thickness, it has been put to practical use and is applicable to various fields expected, due to the specific structure in which a high electric conductivity, tensile strength and heat resistance due to the. However, this in spite of the availability of carbon nanotubes, and carbon nanotubes, there is a limit to their use due to their low solubility and dispersibility. In the composition for forming an electrode was prepared using line was dispersed in a dispersion medium, a carbon nanotube electrode manufacturing carbon nanotubes using. However, the carbon nanotubes have a problem, agglomeration does not form a stable dispersion state in the dispersion medium by strong van der Waals attraction between each other phenomena.
[9]
To solve these problems, there have been various attempts. Specifically, there is a method of dispersing a dispersion medium has been proposed in the carbon nanotubes through a mechanical dispersing treatment such as sonication. However, while applying ultrasonic waves for the method is excellent in dispersibility, but there is a problem when the ultrasonic wave is completed being the aggregation of the carbon nanotubes starts. In addition, there is a method of stabilizing a dispersion of carbon nanotubes have been proposed using a variety of dispersants. However, when these methods also be dispersed in the dispersion medium at a high concentration of carbon nanotubes, there is a problem that viscosity is difficult to handle due to the rise.
[10]
Accordingly, there is a need for a way to improve the dispersibility of the carbon nano-tube electrodes without lowering the conductivity and the development of methods to use them for producing a carbon nanotube dispersion useful for electrode production.
Detailed Description of the Invention
SUMMARY
[11]
The first object of the present invention high-solids-like properties (solid like property) to import, and can be prepared during the collapse and cracking electrode active material having a uniform thickness layer is formed without the occurrence of the loading electrode, and the performance of the resulting battery properties, in particular provides a significant dispersion of the conductive material and a method of manufacturing the same which can improve the capacity characteristics.
[12]
The second object of the present invention to provide a composition for forming an electrode of a lithium secondary battery including the conductive agent dispersion.
[13]
Further, a third object of the present invention to provide a rechargeable lithium battery including the lithium secondary battery, a conductive electrode material prepared using a dispersion, and this.
Problem solving means
[14]
According to one embodiment of the present invention to solve the above problem, the conductive material comprising a bundle-type (bundle-type) carbon nanotubes; Dispersant; And it includes a dispersion medium, and rheometer when the measurement frequency is 1Hz phase provides the conductive material of each dispersion (phase angle) to the a 3 ° to 18 °.
[15]
According to another embodiment of the invention, the bundle-type carbon nanotubes, and then mix the dispersant and the dispersion medium, a rheometer the challenge comprising the measurement frequency milling such that the phase angle is 3 ° to 18 ° when the 1Hz It provides a process for the production of re-dispersion.
[16]
In addition, according to another embodiment of the present invention to provide a composition for forming an electrode of a lithium secondary battery including the conductive agent dispersion.
[17]
According to another embodiment of the present invention, the challenge provides a lithium secondary battery electrode and a lithium secondary battery produced using the re-dispersion.
[18]
More specific details of the embodiments of the invention are included in the following description.
Effects of the Invention
[19]
Conductive material dispersion according to the invention, a strong solid due to similar properties and can be an electrode active material layer formed with a uniform thickness without collapse and crack generation during the loading electrode prepared for, and the performance characteristics of the resulting cells, in particular improve the capacity characteristics can. Accordingly, the conductive material, the dispersion is useful for preparing cells that require high capacity characteristics, such as as well as small batteries for IT devices for automobile battery.
Brief Description of the Drawings
[20]
Following figures attached to this specification are intended to illustrate preferred embodiments of the present invention, the components which serve to further understand the teachings of the present invention with the content of the above-described invention, the invention is only to details set forth in those figures is limited shall not be interpreted.
[21]
Figure 1 of Example 2-1, Example 2-2, Comparative Example 2-1 is a graph of observing the phase angle of the conductive material to the dispersion of Comparative Example 2-3.
[22]
Figure 2 of Example 3-1, Example 3-2, Comparative Example 3-1 is the observed phase angle of the positive pole to the formation of the Comparative Example 3-3 compositions graph.
[23]
3 is a photograph observing the surface of the positive electrode of Example 4-1, Example 4-2, Comparative Example 4-1 to Comparative Example 4-3, a scanning electron microscope.
[24]
4 Example 5-1, Example 5-2, comparative example 5-1 and a comparative graph of observing the rate specific capacity characteristics of the lithium secondary battery of Example 5-3.
Best Mode for Carrying Out the Invention
[25]
Hereinafter, the present invention will be described in more detail to aid the understanding of the present invention.
[26]
Herein and in the terms or words used in the claims is general and not be construed as limited to the dictionary meanings are not, the inventor can adequately define terms to describe his own invention in the best way on the basis of the principle that the interpreted based on the meanings and concepts corresponding to technical aspects of the present invention.
[27]
[28]
A plurality of carbon nanotubes per unit is unit length of the axis in a direction substantially parallel arranged in the same orientation or entangled, the bundle that is not unlike the term "Bundled (bundle type)" is mentioned for use in the present invention (bundle ) or it refers to a secondary shape of the rope (rope) form. In addition, the non-bundled (non-bundle type) or entangled-type (entangled type) "is the CNT units has means to form intertwined without a certain shape, such as a bundle or rope form.
[29]
[30]
The terms used in the present invention, the phase angle (phase angle, δ) 'is generated from the difference between the stress (stress) and strain (stain) is applied to the object. The phase angle is used, so the correlation with viscoelastic, to reflect the basic properties of a viscoelastic material of the conductive material dispersion of the present invention. The viscoelastic means are means that a substance has a viscosity and elasticity at the same time, by the viscous when external energy is applied to the material is the energy decay converted into thermal energy that has been stored temporarily by the elastic back flow out says that.
[31]
Meanwhile, the above solid (ideal solids) is stored when the strain energy of an elastic material (elastic materials), and strain is removed is restored to its original shape. Stress than solid is proportional to the amplitude (amplitude) of the semi-applied strain, the phase angle between stress and strain difference is 0 °. Or more liquid (Ideal liquids) is diverging and the viscous material (viscous materials) strain energy and may be modified has been removed does not recover to its original shape. Stress of the liquid is more than the difference in phase angle between the applied relative to the standard strain rate (strain rate), and stress and strain 90 °.
[32]
[33]
The phase angle of the conductive material dispersion liquid in the present invention can be measured by using a rheometer (rheometer) by methods known in the art, specifically, the same elastic shear rheometer; using (DSR Dynamic Shear Rheometer) 15 a predetermined amount of strain at a temperature of ℃ to 25 ℃, for example a 1% stress, specifically, using the angular frequency of the while applying a stress of 1% of the strain within the linear viscoelastic region at 0.62rad / s to 62rad / s and it can be measured by performing a frequency sweep. In the measurement it may be performed with a frequency sweep to the angular frequency of from 10Hz to 0.1Hz. The smaller the measured phase angle showing the dominant acoustic characteristic, the greater the phase angle has a viscosity is a dominant characteristic.
[34]
[35]
And there is a ongoing research for the expansion of the lithium secondary battery of high energy density in accordance with the dramatic improvement of the energy required per weight for loading the electrode manufacture. For a high load electrode made generally applied to the conductive material with high conductivity, and has been considered a method of increasing the active material through loss of binder ratio. The proper viscosity and dispersibility, and the conductive material having a coating dispersion stability is required for this.
[36]
However, the normal and reduced resistance to loading the composition for electrode formation for and minutes since upon application of carbon nanotubes in the form of a dispersion, a reduction in solids and binder loss is accompanied to the acidic improved, a problem that the viscosity of the composition and the elasticity is reduced a. Furthermore, the time variation of the electrode-forming composition for coating a fast binder lifting phenomenon is not easy to secure deep sea coating stability, as a result, the electrode active material layer has a crack or breakdown occurred in the formation.
[37]
[38]
In the present invention, the bundle-type (bundle-type) using a conductive material containing carbon nanotube and through the phase angle (phase angle) control at the time of electrode manufacture, the conductive material dispersion favorable to the loading electrode produced for tall solid Similar has the property, as a result, it has an excellent coating stability, and provides a uniform coating capable of conducting agent dispersion.
[39]
[40]
That is, the conductive material dispersion liquid in accordance with one embodiment of the present invention,
[41]
Conductive material comprising a bundle-type carbon nanotubes;
[42]
Dispersant; And
[43]
Comprising a dispersion medium,
[44]
When the rheometer measurement frequency 1Hz a phase angle (phase angle, δ) is 3 ° to 18 °.
[45]
[46]
Conductive material dispersion liquid in accordance with one embodiment of the invention is when the rheometer measurement frequency 1Hz phase angle (phase angle, δ) is 3 ° to 18 °. If the phase angle of the conductive material dispersion liquid is less than 3 °, the solid-like properties are too strong coating when it is difficult to conductive material uniformly dispersed in the slurry, and that because of the phase angle when it is more than 18 ° the liquid-like properties are strong, it lowered the viscosity loading is not easy to form the active material layer of uniform thickness, electrode production, there is a fear that cracks occur in the subsequent drying step. When the conductive material dispersion according to the phase angle control of the conductive material dispersion considering the solid-like properties and coating properties of electrode production using the same, and coating stability, the phase angle of the conductive material dispersion is more particularly 3 ° to 15 °, more may be more specifically 3 ° to 10 °.
[47]
In general, the liquid recovery force of the deformation when the external force is applied, that is not elastically deformed. The solid that forms is not possible to continuously deformed when an external force is applied. However, since the one conductivity material dispersion according to an embodiment of the invention is a substance having a viscoelastic (viscoelasticity) characteristic, and the shape can be deformed when external force is applied, regardless of the number of applied force back to the original form of the It can be restored. Viscoelasticity of a conductive material, the dispersion according to one embodiment of the present invention, stress, deformation, time scale, temperature, etc. is applied, but depends on the external conditions, the rheometer when the measurement frequency is 1Hz phase angle (phase angle, δ) is 3 ° to 18 °.
[48]
[49]
The phase angle of the conductive material dispersion as described above may be implemented via control of the conditions during the milling process of the conductive material, the dispersant and the type of the dispersion medium, the physical properties and the mixing ratio, and a manufacturing process of configuring them.
[50]
In addition, carbon nanotubes can have physical properties can vary depending on the units of the carbon nanotube crystallinity and the structure and shape, the amount of metal elements secondary structure and shape of the particle, and contains carbon nanotubes, consisting of the units . Accordingly, by controlling which of the above factors, one or two or more in combination, it is possible to have the physical properties required according to the application of carbon nanotubes.
[51]
[52]
Specifically, according to the conductive material dispersion liquid in accordance with one embodiment of the present invention, a type conductive material comprising the carbon nanotube bundles.
[53]
The carbon nanotube is a secondary structure of the carbon nanotubes per unit formed are set to fulfill the bundled in whole or in part, the CNT units has a cylindrical form of the graphite surface (graphite sheet) The nano-sized diameter, sp 2 It has a coupling structure. At this time, the angle and the structure in which the graphite surface to dry and thus can exhibit the characteristics of a conductor or semiconductor. CNT unit is single-walled carbon nanotube (SWCNT, single-walled carbon nanotube ), double-walled carbon nanotube (DWCNT, double-walled carbon nanotube ) and multi-walled carbon nanotube according to the number of bonding that make up the wall (MWCNT, It can be classified into multi-walled carbon nanotube), and the more the wall thickness is thin low resistance.
[54]
[55]
In the conductive material, the dispersion according to one embodiment of the invention, the carbon nanotube may include any of the carbon nanotubes per unit of single wall, double-wall and multi-wall one or more than one.
[56]
[57]
In addition, the diameter of the carbon nanotubes per unit is too large as a lithium secondary battery, conductive material, per unit volume to that the electrode produced in the energy density disadvantage, and also greatly increases the pore diameter of the electrode because of the increased absolute strands can be reduced conductive material utilization is a density of the electrode can be lowered. Further, if the diameter of the CNT units is too small, difficult to disperse dispersion prepared fairness is falling, the dispersed carbon nanotube units or carbon nanotube is buried in a space between the electrode active material particles, it is difficult to have enough pore formation. Accordingly, the electrode as the average strand diameter of a carbon nanotube unit in the carbon nanotubes usable in the invention can be less than 30nm, increasing conductive material dispersibility improved and the solid-like properties according to the diameter of the control of the unit effectiveness, and the results considering the improved stability of the coating composition for forming effect, an average strand diameter of the carbon nanotubes per unit may be a 10nm to 30nm. The CNT unit refers to a strand of carbon nanotubes.
[58]
[59]
Further, the longer the carbon nanotube unit in the life property of the electric conductivity of the electrode, and the high temperature strength and the room temperature can be improved. If there since the length of carbon nanotubes per unit is difficult to form a conductive path short-effective is a fear that the electrical conductivity decreases. On the other hand, there is a fear that the length of the carbon nanotubes per unit is too long, the dispersibility decreases. Accordingly, the length of the unit in a carbon nanotube can be used in the present invention may be a 0.5㎛ to 200㎛. In addition, given the diameter of the carbon nanotubes per unit, the CNT units has went by the center of the carbon nanotube length (length of the long axis passing through the center of the unit) and the diameter of the unit (unit, perpendicular to the longitudinal axis the aspect ratio is defined as the ratio of the length of the minor axis) it may be from 5 to 50,000, and may be more specifically 10 to 20,000.
[60]
In the present invention, the strand diameter and the length of the carbon nanotubes per unit can be measured using a field emission scanning electron microscope.
[61]
[62]
On the other hand, a carbon nanotube comprising a carbon nanotube unit as described above is the true density may be in the 70 to 120 ratio (TD / BD ratio) of:: (BD Bulk Density) (True Density TD) and bulk density.
[63]
In the present invention, the true density (TD) and there from the ratio of the bulk density (BD) to predict the internal structure of the carbon nanotube, and capacity characteristics of the battery because of TD / BD ratio is too large, the carbon nanotube is low the content of the monomer this has a risk of degradation, if the addition ratio is too small, TD / BD there is a possibility that the dispersibility of the carbon nanotube decreases. Bulk density and true dispersion and the battery characteristics according to the ratio control of the density effects, and further considering an increase in the solid-like properties effects, TD / BD ratio of the carbon nanotubes can be used in the present invention is specifically 70 to 100 than can.
[64]
[65]
Specifically, the true density of the carbon nanotubes can be used in the present invention 1,800㎏ / ㎥ to 2,200㎏ / ㎥, more specifically, 1,900㎏ / ㎥ to 2,200㎏ / ㎥ under conditions that satisfy the above-described TD / BD ratio one can.
[66]
[67]
In addition, the bulk density of the carbon nanotubes 10㎏ / ㎥ to 50㎏ / ㎥ under conditions that satisfy the above-described TD / BD ratio, and more specifically may be a 20㎏ / ㎥ to 40㎏ / ㎥. The conductivity and the dispersibility of carbon nanotubes, by having a bulk density in the above range can be improved.
[68]
[69]
In the present invention, the bulk density of the carbon nanotubes can be determined according to the following equation (1). Specifically, the to, after measuring the weight of powder filled in 25㎖ container of known weight can be converted to the density according to equation (1).
[70]
Equation 1
[71]
Bulk density (㎏ / ㎥) = CNT weight (㎏) / CNT volume (㎥)
[72]
[73]
Further, in the above-mentioned conductive material dispersion liquid in accordance with one embodiment of the present invention, the carbon nanotubes exhibit excellent dispersibility obtain the high BET surface area, because as described above the diameter of the unit is small, TD / BD ratio Size can. Specifically, the BET specific surface area of ​​the carbon nanotube can be used in the present invention may be 180㎡ / g to 300㎡ / g, more specifically, 200㎡ / g to 300㎡ / g, more specifically than 230㎡ / g and may be 300㎡ / g.
[74]
In the present invention, the specific surface area of ​​the carbon nanotubes as measured by the BET method, specifically, can be calculated using the BEL Japan Inc. BELSORP-mino Ⅱ from nitrogen gas adsorption amount at the liquid nitrogen temperature, and (77K) have.
[75]
[76]
Further, in the above-mentioned conductive material dispersion liquid in accordance with one embodiment of the present invention, the carbon nanotubes is 1580 ± 50 ㎝ obtained by the Raman spectroscopic analysis using a laser of wavelength 532㎚ -1 up to the peak intensity of G-band of the ( IG) 1360 ± 50 ㎝ to -1 may be a non-(ID / IG) is an average value of 0.7 to 1.2 of the maximum peak intensity (ID) of the D band at.
[77]
[78]
Raman spectrometry is a useful method in a method for analyzing the structure of the carbon nanotubes, the surface state analysis of the carbon nanotubes. Raman spectrum of a wave number of 1,570 ~ 1,580㎝ CNT -1 is called a peak present in the region in the vicinity of the G band, which is the sp carbon nanotubes 2 as a peak representing a bond, indicates the carbon crystal structure without a defect. On the other hand, the Raman spectrum of a wave number 1,350 ~ 1,360㎝ -1 peak present in the region in the vicinity of the called D band, which is the sp carbon nanotubes 3 as a peak indicating a bond, sp 2 atomic bond consisting of a bond broken sp 3 bond It increases when the. Such a D band is up to the peak intensity of D-band of the disorder (disorder) to the defect (defect), or because the increase when the amorphous is generated, a maximum peak intensity (IG) of G-band present in the carbon nanotubes ( by calculating the ratio (ID / IG) of the ID) it can be evaluated to generate the degree of disorder (disorder) to the defect (defect) quantitatively.
[79]
[80]
G band in Raman spectrum for the carbon nanotubes in the present invention is a wave number 1580 ± 50㎝ -1 may be a peak in an area, D band frequencies 1360 ± 50㎝ -1 may be a peak in an area. Wave number range with respect to the G-band and D band is within the scope that can be shifted in accordance with the laser light source used for the Raman spectrometry. Raman value to be used in the present invention is not particularly limited, it is possible using the DXR Raman Microscope (Thermo Electron Scientific Instruments LLC) measured at a laser wavelength 532㎚.
[81]
[82]
Conventional G band lower the peak integration value and the D band ratio value peak integration larger the amorphous carbon is large amount, or would mean that the crystalline defects of the carbon nanotubes, in the present invention, the increase in the BET specific surface area of ​​the bundle-like structure but preferably the crystallinity of the carbon nanotubes will have an average value of ID / IG as described above in accordance with having a secondary shape.
[83]
[84]
In addition, the carbon nanotubes of a main catalyst or co-catalyst is used in the manufacturing process, the metal elements Fe 50ppm or less, and more particularly may comprise an amount of 20ppm or less. Thus, by significantly reducing the residual Fe as an impurity metal content of the carbon nanotube it can exhibit a more excellent conductivity without concern about side reactions within the electrodes. In the present invention, the content of the residual metal to carbon nanotube impurities may be analyzed with a high-frequency inductively coupled plasma (inductively coupled plasma, ICP). In addition, the carbon nanotubes may or may not contain Fe.
[85]
[86]
Carbon nanotubes as described above may be used to manufacture may be used either commercially available, or directly. When manufacturing, the arc discharge method, laser evaporation method, or may be prepared using conventional methods, such as chemical vapor deposition, the physical properties over the control, such as type, removing the heat treatment temperature and the impurities of the catalyst in manufacturing method a it can be implemented.
[87]
[88]
In particular, when prepared in accordance with the chemical vapor phase synthesis, the carbon nanotubes by contacting the supported catalyst with a metal catalyst on a spherical alumina support bearing α- under a carbon source to the heating step for producing a carbon nanotube, and optionally depending can be selectively prepared by the method comprising the step of removing the metal impurities in carbon nanotubes.
[89]
[90]
Producing a carbon nanotube according to the chemical vapor phase synthesis method is, more specifically, lower than the melting point of the metal catalyst supporting the supported catalyst to the horizontal fixed-bed reactor, or placed in a fluid bed reactor, at least the thermal decomposition temperature of the gaseous carbon source to the supported catalyst a carbon source at a temperature; Or the carbon source and the reducing gas may be performed by (for example, hydrogen, etc.) and carrier gas (e.g., nitrogen) is injected into the gas mixture growing carbon nanotubes by chemical vapor phase synthesis over the carbon source decomposition of . Carbon nanotubes manufactured by chemical vapor phase synthesis as described above and the growth direction of the crystal substantially parallel to the tube axis, it is highly graphite crystalline structure as the tube longitudinal direction. As a result, the smaller the diameter of the unit, a high electrical conductivity and strength.
[91]
[92]
In addition, the production of the carbon nanotubes, specifically, a temperature of less than 500 ℃ 800 ℃, and more specifically may be carried out at 550 ℃ to 700 ℃. Within the reaction temperature range, because the weight is reduced while maintaining the bulk size of the carbon nanotube to be produced while minimizing the generation of non-crystalline carbon, and the dispersibility according to the reduced bulk density it can be further enhanced. As the heat source for the heat treatment inductive heating (induction heating), there is radiant heat, laser, IR, microwave, plasma, surface plasmon heating, can be used.
[93]
[94]
Further, as the carbon source is capable of supplying carbon, so long as it can be present in the gas phase at above 300 ℃ temperature can be used without particular limitations. More specifically, it may be a carbon based compound having a carbon number of 6 or less, and more specifically, carbon monoxide, methane, ethane, ethylene, ethanol, acetylene, propane, propylene, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, and the like benzene or toluene, there is any one or a mixture of two or more of them may be used.
[95]
[96]
Then by a heat treatment, such as the growth of carbon nanotubes, cooling step for regularly aligned than the array of carbon nanotubes it can optionally be further performed. The cooling process may be specifically carried out using a self-cooling or the like according to the condenser of the heat source removed.
[97]
[98]
On the other hand, the catalyst used in the production of the carbon nanotubes, may be a metal catalyst in a spherical α- alumina support bearing.
[99]
α- alumina has a very low utilization as a porous catalyst support is very low compared to the γ- alumina. However, by controlling the firing temperature at which the supported catalyst is formed by using this, while suppressing the carbon nanotubes during the generation of amorphous carbon to reduce the specific surface area it may increase the diameter. At the same time to reduce the bulk density of the carbon nanotubes may improve the dispersibility.
[100]
[101]
Specifically, the α- alumina is available as a support in the invention is the average particle diameter (D 50 and a 20 to 200㎛), may be one having a BET specific surface area of 1 to 50㎡ / g. In Fig it said α- alumina has a very low porosity smoother the surface, may be specifically, having a porosity of 0.001 to 0.1㎤ / g.
[102]
[103]
On the other hand, the containing of the α- alumina spherical support with the supported catalyst may be prepared by firing after loading of the metal catalyst in the α- alumina support of the above-described spherical shape. Specifically, the supported catalyst and mixed with the one prepared by dissolving a precursor of the metal catalyst with water the metal catalyst precursor solution added to α- alumina support of the sphere, carried out by baking at a temperature not higher than 600 ℃ It can be.
[104]
[105]
Metal catalyst to be supported on the support and serves to help the carbon components present in the gaseous carbon source to form a 6-membered ring structure are bonded to each other. In the metal catalyst is iron, nickel or may be a main catalyst of cobalt and the like used alone, or the main catalyst is a main catalyst with a cocatalyst, such as molybdenum, vanadium or chromium-may be used in the form of a co-catalyst complex catalyst . Specifically, the complex catalyst and the like FeCO, CoMo, CoV, FeCoMo, FeMoV, FeV, or FeCoMoV, there is any one or a mixture of two or more of them may be used. In addition, the co-catalyst to the main catalyst is one mole of 0.01 to 1 mole, and more specifically, may be used in an amount of 0.05 to 0.5 mol.
[106]
[107]
In the production of a supported catalyst, the precursor to the metal catalyst and the like, soluble metal salt or metal oxide in water can be used, specifically, Ni, Co, Mo, one or more selected from V and Cr It may be a metal salt, a metal oxide and a metal halide containing at least a metal element. More specifically, the Co (NO 3 ) 2 · 6H 2 O, Co 2 (CO) 8 , [Co 2 (CO) 6 (t-BuC = CH)], Cu (OAc) 2 , Ni (NO 3 ) 2 · 6H 2 O, (NH 4 ) 6 Mo 7 O 24 · 4H 2 O, Mo (CO) 6 , (NH 4 ) MoS 4 and NH 4 VO3 is any one or a mixture of two or more selected from the group consisting of may be used.
[108]
[109]
In addition, precursors of the metal catalyst may be used as an aqueous solution dissolved in water, at this time, and in consideration of the impregnation efficiency, the concentration of the metal catalyst precursor in the aqueous solution can be properly adjusted. Specifically, the metal concentration in the catalyst precursor in an aqueous solution may be 0.1g / ㎖ to 0.4g / ㎖.
[110]
[111]
Further, in consideration of the content of the support in the supported catalyst to be finally manufactured, the content of the metal catalyst precursor and the α- alumina support of the rectangle to be mixed may be determined as appropriate.
[112]
[113]
In addition, when the support is added and mixed in the metal catalyst precursor solution for bulk density control of CNT acid it may optionally be used further. Thus, if the acid is further added to the metal catalyst precursor solution more specifically, metal catalysts 3 to 40 mol, for 1 mol of acid may be used in an amount corresponding to 5 moles to 30 moles. The acid or the like can be specifically citric acid, may be used any one or a mixture of two or more of them.
[114]
[115]
On the other hand, mixing of the metal catalyst precursor solution and α- alumina support of the sphere can be carried out according to a conventional method, specifically, it may be performed by rotating or stirring under 45 ℃ to 80 ℃ temperature.
[116]
Further, in consideration of the content of the metal catalyst to be supported on the supported catalyst that is prepared during the final mixture can be mixed in the metal catalyst precursor and the support. The more the supported amount of the metal catalyst increases in the supported catalyst, there is a tendency that the bulk density of the carbon nanotube growth to be produced using the supported catalyst. Accordingly, taking into account the bulk density of the carbon nanotubes is prepared, a catalyst metal based on the total weight of the supported catalyst to be finally produced can be mixed so as to be supported in an amount of 5 to 30% by weight.
[117]
[118]
Further, after the mixture of the metal catalyst precursor solution and α- alumina support of the sphere, the above drying step, the firing step may optionally be further performed. The drying step can be carried out according to a conventional method, specifically, is from 40 ℃ to 100 ℃ temperature may be carried out by rotary evaporation for 3 minutes to one hour under vacuum.
[119]
[120]
Subsequently, the firing for the mixture of the metal catalyst precursor and a support prepared by the method described above is carried out. The calcination is 600 ℃ or less, specifically, it can be carried out in air or an inert atmosphere at a temperature of 400 ℃ to 600 ℃.
[121]
[122]
In addition, after the aforementioned drying step, and baking step calcination process at 250 ℃ to a temperature of 400 ℃ before this may optionally be further performed.
[123]
At this time, just prior to the preliminary calcination, considering the efficiency of reaction, the metal catalyst precursor and the used impregnated with up to 50% of a mixture of the support in the α- alumina support, and the mixture immediately after the calcination of said glass α- It may be impregnated on an alumina support.
[124]
[125]
A removal step for removing the resulting metal catalyst, metal impurities, which remain in the carbon nanotubes to the carbon nanotubes produced by the production process as described above can optionally be further carried out, and, in which the metal impurity removal step is washed, It can be carried out by a conventional method such as acid treatment.
[126]
[127]
Production method of bundled carbon nanotubes prepared according to as described above has excellent conductivity, and the conductive material during manufacturing the conductive material dispersibility improvement of the dispersion and a solid-like properties increased effectiveness, and improved coating stability of the electrode forming composition as a result It may exhibit the effect. It can also be a high purity, increased improve the output characteristics of the battery applied when the cell performance, especially in the cell conductive electrodes.
[128]
[129]
On the other hand, in the conductive material, the dispersion according to one embodiment of the invention, the dispersant is so long as it is used to improve the dispersibility of the conventional carbon nanotubes can be used without particular limitation.
[130]
[131]
Specifically, according to the conductive material dispersion liquid in accordance with one embodiment of the present invention, the dispersant may be may be a nitrile-based rubber, and more particularly to a butadiene-based rubber hydrogenated in part or in whole nitrile.
[132]
[133]
The hydrogenated nitrile butadiene rubber comprises a specific structural unit derived from the conjugated diene hydrogenated, α, β- unsaturated nitrile-derived structural unit and a structural unit derived from a conjugated diene, wherein the hydrogenated conjugated diene rubber, relative to the total weight of structural units derived from a may be one that contains 20% to 80% by weight. When included in an amount as described above, the increased miscibility of the dispersion medium increases the solid-like properties of the carbon nano-dispersibility increase at the same time the conductive material dispersion liquid can be the tube and to improve the coating stability of the electrode forming composition as a result can. More specifically, it may be one containing the hydrogenated conjugated diene-derived structural unit on the total weight of rubber with 30% to 70% by weight.
[134]
[135]
In addition, given the minute miscibility with improved acid and the dispersion medium to the carbon nanotubes, the amount of hydrogenated nitrile butadiene rubber in α, β- unsaturated nitrile-derived structural unit is to 10% by weight relative to the total weight of the rubber 70 % by weight, specifically, it may be a 20 to 60 wt%. When including the α, β- unsaturated nitriles structure-containing repeating unit in the above-described content range, it is possible to improve the dispersibility of carbon nanotubes, it is possible to increase the solid-like properties of the conductive material dispersion.
[136]
[137]
Considering the solid-like properties improvement and improved coating stability of the composition for forming an electrode comprising the same effect of the conductive material dispersion liquid in accordance with the content of control of the repeating unit structure constituting the rubber, acrylonitrile-butadiene-based rubber of the hydrogenation for the rubber total weight , a hydrogenated conjugated diene-derived structural units of 20% by weight to 80% by weight; α, β- unsaturated nitrile structural units derived from 10 wt% to 70 wt%; And it may be a structure derived from a conjugated diene butadiene rubber partially hydrogenated nitrile containing units of 1% to 15% by weight.
[138]
[139]
In the present invention, the content of the hydrogenated nitrile butadiene rubber in the nitrile-containing repeating structural units, α, in a weight ratio to the total rubber of the structural unit derived from β- unsaturated nitriles, the art measurement of the content, JIS K 6364 Thus on the wheat of the oven method, in terms of its binding capacity measured from the amount of nitrogen generated and the molecular weight of the acrylonitrile, a middle value of the quantization value.
[140]
[141]
Further, the hydrogenated nitrile butadiene rubber may be prepared by hydrogenating the conjugated diene, α, β- unsaturated nitriles, and optionally other copolymerizable monomers within three won C = C double bond, then copolymerizing a (termonomer), copolymers with . At this time, the polymerization process and the hydrogenation process may be carried out in a usual manner.
[142]
[143]
α, β- unsaturated nitriles with possible use in the manufacture of a butadiene-based rubber of the nitrile hydrogenation may be mentioned specifically as acrylonitrile or methacrylonitrile, there are singly or as mixtures of two or more thereof may be used of which .
[144]
In addition, the possible use in the manufacture of a conjugated diene wherein the hydrogenated nitrile butadiene rubber may be mentioned specifically 1,3-butadiene, isoprene or 2,3-butadiene-methyl, such as a conjugated diene with a carbon number of 4-6, of which It is any one or a mixture of two or more may be used.
[145]
Further, as other copolymerizable monomers usable as the optional three won is specifically an aromatic vinyl monomer (e.g., styrene, α- methyl styrene, vinyl pyridine, and a fluoroalkyl vinyl ether, etc.), α, β- unsaturated carboxylic acid (e. g., acrylic acid, methacrylic acid, maleic acid, fumaric acid, etc.), α, β- unsaturated carboxylic acid ester or amide (e.g., methyl (meth) acrylate, ethyl (meth) acrylate, n- dodecyl (meth) acrylate, methoxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, or polyethylene glycol (meth) acrylate, etc.), or α, β- unsaturated dicarboxylic anhydride of the acid and the like (for example, maleic anhydride, itaconic anhydride or citraconic anhydride), but it is not limited to this.
[146]
[147]
In the hydrogenated nitrile butadiene rubber produced according to the same method as described above, a hydrogenated conjugated diene-derived structural units, α, β- unsaturated nitrile-derived structural units, the structural unit derived from a conjugated diene and, optionally, other copolymerizable monomer-derived structure three won the content ratio of the units can vary within a wide range, the sum of said structural unit in each case is 100% by weight.
[148]
[149]
In addition, acrylonitrile, the hydrogenated acrylonitrile-butadiene rubber (H-NBR) may be one of a weight average molecular weight of 10,000g / mol to about 700,000g / mol, more particularly to 10,000g / mol to about 300,000g / mol. In addition, acrylonitrile, it said partially hydrogenated acrylonitrile-butadiene rubber (H-NBR) in the range of 2.0 to 6.0, specifically, the ratio of the 2.0 to 4.0 range of polydispersity index PDI (Mw / Mn Mw is the weight average molecular weight of Mn number may be one having a number average molecular weight Im). When the H-NBR having a weight average molecular weight and polydispersity index of the above-described range, it is a conductive material containing carbon nanotubes can be uniformly dispersed in the dispersion medium. In the present invention, the weight average molecular weight and number-average molecular weight is expressed in terms of polystyrene molecular weight analysis by gel permeation chromatography (GPC).
[150]
[151]
On the other hand, such as in the above conductive material dispersion liquid in accordance with one embodiment of the present invention, the dispersion medium of dimethylformamide (DMF), diethyl formamide, dimethyl acetamide (DMAc), N- methylpyrrolidone (NMP) amide-based polar organic solvent; Methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol (n- butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec- butanol), 1-methyl 2-propanol (tert- butanol), alcohols such as pentanol, hexanol, heptanol or octanol and the like; Glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, or hexylene glycol; Polyhydric alcohols, glycerol, and trimethylolpropane, pentaerythritol, sorbitol or the like; Ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monobutyl ether and glycol ethers; Acetone, methyl ethyl ketone, methyl propyl ketone, or ketones such as cyclopentanone; Ethyl acetate, γ- butyrolactone, propiolactone and ε- may be made of esters, such as entertainment tone, the any one or a mixture of two or more of them may be used. More specifically, it is the dispersion medium is daily for amide-based polar organic considering the dispersibility-improving effect on the carbon nanotube and a dispersing agent.
[152]
[153]
In the conductive material dispersion liquid in accordance with one embodiment of the present invention having the configuration described above, the content of the conductive material and a dispersion medium containing the above-mentioned dispersing agent, a bundle-type carbon nanotubes can be suitably determined according to the usage of the dispersion.
[154]
[155]
More specifically, the dispersing agent for uniformly dispersing the carbon nanotubes in the dispersion may be included in an amount of 1 part by weight to 50 parts by weight based on 100 parts by weight of carbon nanotubes. When the content of the dispersant is less than 1 part by weight, it is difficult to uniformly disperse the carbon nanotubes in the dispersion, there is a fear of exceeding 50 weight parts of the coating for the electrode made of the increased viscosity of the dispersion electrode-forming composition and coating stability decreases.
[156]
[157]
In addition, the carbon nanotubes may be included to 1% by weight to 33% by weight relative to the total weight of the conductive material dispersion. When the carbon nanotubes contained in an amount within the above range can exhibit electron conductivity and dispersibility good balance. If the content of the carbon nanotubes is less than 1% by weight out of the range, and that the electrode produced when using the electrode-forming composition of the lithium secondary battery contains a large amount of organic solvent, for example, increased as a result, the electrode within the pores and the active material filling rate is lowered thereby can be a battery capacity decrease. In addition, it is possible to lengthen the drying time for the removal of organic solvent. Further, if the content of the carbon nanotubes exceeding 33% by weight, the mixed dispersion of the carbon nanotubes is reduced, there is a fear that the resulting coating properties and coating stability decreases for electrode electrode forming composition in the manufacture. More specifically, the carbon nanotube may comprise from 1 wt% to 8% by weight based on the total weight of the conductive material dispersion.
[158]
[159]
Can be further included Specifically, the above conductive material dispersion liquid in accordance with one embodiment of the invention the dispersing agent 1 part by weight to 50 parts by weight per 100 parts by weight of the carbon nanotubes, and the dispersion medium to 200 parts by weight to 9,900 parts by weight, . To meet the above-described content ratio conditions at the same time, the phase can exhibit a high solid-like properties to satisfy the respective conditions, as a result, can greatly improve the coating properties and the stability of the coating composition for forming an electrode.
[160]
[161]
In addition, the conductive material dispersion liquid in accordance with one embodiment of the present invention may further include a dispersion stabilizer to improve the dispersion stability.
[162]
The dispersion stabilizer may prevent the aggregation of carbon nanotubes, by indicating the wrapping effect is to adsorb to the surface of the carbon nanotubes surrounding the carbon nanotube. Accordingly, the dispersion stabilizing agent, at the same time is excellent in affinity to the carbon nanotubes, it may be desirable excellent in miscibility with the dispersant and the dispersion medium.
[163]
[164]
Specifically, in one embodiment the conductive material, the dispersion according to the present invention, the dispersion stabilizer is a polyvinylidene fluoride, or polyvinyl pyrrolidone may be a fluorinated polymer such as money, or more of either or both of these the mixture may be used.
[165]
[166]
Further, the dispersion stabilizer may be one of a weight average molecular weight of 20,000g / ㏖ to 5,000,000g / ㏖. If the molecular weight of the dispersion stabilizer is too small to be less than 20,000g / ㏖, indicate sufficient lapping effect on the carbon nanotube is difficult, and the molecular weight is decreased molecular movement of the dispersion stabilizer of the dispersion medium is too large in excess of 5,000,000g / ㏖ a, it is difficult to fully wrapped carbon nanotubes. More specifically, the dispersion stabilizer may be one of a 70,000g / ㏖ to 2,000,000g / ㏖ weight average molecular weight.
[167]
[168]
Further, the dispersion stabilizer can be used in an amount of 1 part by weight to 10 parts by weight based on 100 parts by weight of carbon nanotubes. If the content of the dispersion stabilizer compared to the content of the carbon nanotube is too low, it is difficult to obtain sufficient trapping effect, so that there is a fear that aggregation between the carbon nanotube occurs.
[169]
[170]
Conductive material dispersion liquid in accordance with one embodiment of the present invention having the configuration as described above, and then mixed with a conductive material, a dispersant and a dispersion medium comprising a bundle-type carbon nanotubes, phase when the rheometer measurement frequency 1Hz each (phase angle) can be produced by a production method including the step of milling such that a 3 ° to 18 °. The carbon nanotubes and the conductive material, the type and amount of dispersant and the dispersion medium comprising the same is the same as described above.
[171]
[172]
The conductive agent, the dispersing agent and mixing the dispersion medium may be performed in a usual manner. Specifically, there is a cavitation distribution process may be performed in order to improve the dispersibility of the carbon nanotubes with the dispersion medium mixed, or carbon nanotubes in the dispersion medium of. The cavitation dispersion treatment may be dispersed as a dispersion method using a handsome shock by that looking vacuum bubbles in water by applying a voltage of a high energy to the liquid burst, without damaging the characteristics of the carbon nanotubes by the method . More specifically, the cavitation dispersion treatment may be performed by ultrasonic waves, a jet mill, or shear dispersion process.
[173]
[174]
The dispersion process may be appropriately performed depending upon the amount and type of dispersing agent of CNT. Specifically, when performing the ultrasonic treatment, the range of frequencies to 10㎑ 150㎑, the amplitude is in the range of 5㎛ to 100㎛, the irradiation time may be 1 minute to 300 min. As the ultrasonic generator for carrying out the ultrasonic processing process, for example, it may be used, such as ultrasonic homogenizer. In the case to perform a jet milling process, the pressure may be performed 20㎫ to be 250㎫ and, once more, specifically, a plurality of times more than once. In addition, as the jet mill dispersion apparatus and the like can be used high-pressure liquid jet milling.
[175]
[176]
The cavitation dispersion treatment step the temperature is not specifically limited, but can be carried out without the risk of evaporation of a change in viscosity of the dispersion according to the temperature of the dispersing medium. Specifically, more specifically, less than 50 ℃, it may be carried out at a temperature of 15 ℃ to 50 ℃.
[177]
[178]
Further, in the manufacture of a conductive material, the dispersion according to one embodiment of the invention, the milling is ball mill (ball mill), a bead mill may be performed by methods such as and (bead mill), or a basket mill (basket mill) and, more particularly, it may be performed by a milling method using a bead mill.
[179]
[180]
In addition, when the milling by the bead mill, a bead mill size of the conductive material type and amount, and may be properly determined depending on the type of dispersing agent, specifically, the bead mill diameter 0.5㎜ to 2㎜, more specifically, 1 may be ㎜ to 2㎜. In addition, the bead milling process may be carried out at a speed of 2,000rpm to 4,500rpm, and more specifically may be carried out at a speed of 2,000rpm to 3,000rpm.
[181]
[182]
The milling process is a phase angle of the conductive material, the dispersion can be carried out under the conditions to meet the above conditions, specifically, may be performed for 60 to 120 minutes, more specifically from 60 minutes to 90 minutes.
[183]
[184]
The dispersion stabilizing agent in the preparation of the dispersion may optionally be used more, the dispersion stabilizer may be added together at the time of mixing of the dispersant. In this case, the manufacturing method of the conductive material dispersion liquid in accordance with one embodiment of the present invention may further include a dispersion stabilizer addition process. Type and amount of the dispersion stabilizer is the same as described above.
[185]
[186]
In the dispersion medium according to the manufacturing method such as the carbon nanotube has a conducting agent dispersion can be prepared with a high solid-like properties at the same time to be uniformly dispersed.
[187]
Specifically, in the above-mentioned conductive material dispersion liquid in accordance with one embodiment of the present invention, the carbon nanotubes and the dispersant, a carbon nanotube introduced into the dispersing agent is through physical or chemical bonding to the surface of the carbon nanotubes in the form of a dispersant complex as it may be included in the dispersion.
[188]
[189]
More specifically, in the conductive material, the composite dispersion has a particle size distribution D of 99 to less than 100㎛, more specifically, to 20㎛ 70㎛, more specifically, it may represent a 30㎛ 50㎛ to the distribution.
[190]
The particle size distribution of the composite D 99 is defined as a particle diameter at 99% based on the particle size distribution. In addition the particle size distribution D of the composite 99 , for example, a laser diffraction method (laser diffraction method) a can be measured by, more specifically, after dispersing the composite in a solvent, a commercially available laser diffraction particle size measuring apparatus after investigating about the 28㎑ ultrasound is introduced (for example Microtrac MT 3000) to output 60W, the average particle diameter (D 99% of the basis of the particle size distribution of the measuring device 99 can be calculated).

Claims
[Claim 1]
Bundled (bundle-type) conductive material containing carbon nanotubes; dispersing agents; And it includes a dispersion medium and a rheometer measurement frequency dispersion of phase to the angle of 3 ° to 18 ° when the conductive material 1Hz.
[Claim 2]
The method of claim 1, wherein the carbon nanotubes of the conductive material and having an average dispersion diameter of the strands comprises a 10㎚ to 30㎚ the CNT units.
[Claim 3]
The method of claim 1, wherein the carbon nanotubes the dispersion of the conductive material is included as 1% to 33% by weight, based on the total weight of the conductive material dispersion.
[Claim 4]
The method of claim 1 wherein the dispersant is a dispersion of the conductive material comprises a nitrile butadiene rubber.
[Claim 5]
The method of claim 1 wherein the dispersant is a dispersion of a hydrogenated acrylonitrile-butadiene-based rubber comprises a conductive material comprising a hydrogenated conjugated diene-derived structural units relative to the total weight of rubber with 20% to 80% by weight.
[Claim 6]
The method of claim 5, wherein the hydrogenated nitrile butadiene rubber is the rubber with respect to the total weight, α, β- unsaturated nitriles dispersion of the conductive material comprises a structural unit derived from a 10% to 70% by weight.
[Claim 7]
According to claim 5, wherein the hydrogenated nitrile butadiene rubber relative to the total weight of rubber, a hydrogenated conjugated diene-derived structural units of 20% by weight to 80% by weight; α, β- unsaturated nitrile structural units derived from 10 wt% to 70 wt%; And conjugated diene-derived structural unit first dispersion of conductive material, partially hydrogenated nitrile rubber to butadiene comprises by weight% to 15 weight%.
[Claim 8]
The method of claim 5, wherein the hydrogenated nitrile butadiene rubber has a weight average molecular weight of 10,000g / ㏖ to 700,000g / ㏖, and a polydispersity index of dispersion of the conductive material to 2.0 to 6.0.
[Claim 9]
The method according to claim 1, wherein the dispersant is a dispersion of the conductive material will be included an amount of 1 part by weight to 50 parts by weight per 100 parts by weight of the carbon nanotubes.
[Claim 10]
The method of claim 1, wherein the dispersing agent is introduced to the surface of the carbon nanotubes, the carbon nanotube-dispersing agent complex to form the carbon nanotube-dispersant complex is the particle size distribution D 99 is not more than 100㎛, the dispersion total weight for the conductive material, the dispersion is included in an amount of 1 to 5% by weight.
[Claim 11]
The method of claim 1, wherein the dispersion medium is the dispersion of the conductive material to the amide-based organic solvent.
[Claim 12]
The method according to claim 1, wherein the conductive material dispersion is the dispersion a conductive material, characterized in that is used as a conductive material for a lithium secondary battery electrode.
[Claim 13]
After mixing a conductive material, a dispersant and a dispersion medium comprising a bundle-type carbon nanotubes, rheometer measurement frequency of the first term conductive material dispersion comprising the steps of milling such that the phase angle when the 1Hz is 3 ° to 18 ° method.
[Claim 14]
The method of claim 13 wherein the milling method of producing a conductive material, the dispersion is performed by a bead mill.
[Claim 15]
15. The method of claim 14 wherein the milling mean diameter 0.5㎜ to using a bead mill for 60 to 120 minutes 2㎜ method of producing a conductive material, the dispersion is performed for.
[Claim 16]
The electrode active material; bookbinder; And any one of claims 1 to 12, wherein any one of the compositions for forming an electrode of a rechargeable lithium battery including the conductive material, the dispersion according to.
[Claim 17]
17. The method of claim 16 wherein the conductive material dispersion liquid composition for forming an electrode of a lithium secondary battery is included as 1% to 50% by weight relative to the total weight of the composition for forming an electrode.
[Claim 18]
Of claim 16 wherein the electrode-forming composition for the secondary battery is a rheometer measurement frequency 1Hz one when the phase angle is 15 ° to 35 ° to the composition for forming an electrode of a lithium secondary battery in.
[Claim 19]
The lithium secondary cell electrode produced by using a composition for forming an electrode according to claim 16.
[Claim 20]
anode; cathode; Comprising a separator and an electrolyte, wherein at least one of the positive electrode and the negative electrode is a lithium secondary battery electrode, to a lithium secondary battery according to claim 19.