Art
[1]
Mutual citations and related applications
[2]
This application claims the benefit of priority based on the Korea Patent Application No. 10-2016-0147950 filed on November 8, dated 2016, and all information disclosed in the literature of the Korea patent application are included as part of the specification.
[3]
[4]
Art
[5]
The present invention is characterized in that a second particle that, specifically, in the negative electrode is 0.94 to 0.98, the sphericity of the first particles and the sphericity is 0.70 to 0.92 on the negative electrode and the method for producing the negative electrode.
BACKGROUND
[6]
And the demand for the use of alternative energy and clean energy increased due to the rapid increase in the use of fossil fuels, is the development, storage areas are areas that have been studied most actively in that part using an electrochemical reaction.
[7]
Typical examples include a secondary battery of the present electrochemical device using such an electrochemical energy, and the trend that more and more expanding its area of ​​use. Recently, portable computers, portable phones, the demand of secondary batteries has rapidly increased as an energy source, as the technical development and need for a portable apparatus such as a camera is increased, such a secondary battery of high energy density, that is, high-capacity lithium secondary battery many studies been performed on, it is also commercially available and widely used.
[8]
In general, the secondary battery is composed of a positive electrode, a negative electrode, an electrolyte, and a separator, the first lithium ions emitted from the positive electrode active material by the first charge is inserted into the anode active material such as carbon particles, while reciprocating the positive electrode such as to be desorbed back during discharge because it serves to transmit energy it is possible to charge and discharge. Electrode uses the binder of the binder and the like to improve adhesion include a current collector and active material layer, generally between the active material and the current collector.
[9]
Conventionally, in order to increase further the adhesiveness, adding extra additives to the electrode or slurry, it is described to introduce increasing the proportion of binder. However, in the case of adding the additives, or the binder content increases, there is a problem that the amount of the active material particles is reduced to reduce the capacity.
[10]
Accordingly, it is, while maintaining a high capacity of battery, the adhesion between the active material and the current collector is required development of an electrode that can be secured.
[11]
[Prior art document]
[12]
[Patent Document]
[13]
Patent Document 1: Republic of Korea Laid-Open Patent Publication No. 10-2004-0053492 No.
Detailed Description of the Invention
SUMMARY
[14]
One object of the present invention to provide a cathode and a method which can improve the adhesive force (adhesion electrode) between the negative electrode active material layer and the house.
Problem solving means
[15]
In accordance with one embodiment of the present invention, there is provided a current collector and a negative electrode comprising a negative active material layer disposed on the current collector, the negative electrode active material layer comprises first particles and second particles, said first particles a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and in that the sphericity measured by the particulate analyzer of 0.70 to 0.92, the artificial graphite, the weight ratio of the second particles with the first particles is from 1: 9 is provided with the cathode: 1 to 1.
[16]
According to a further embodiment of the present invention, preparing a negative electrode slurry (the first step) and the production method of the negative electrode, comprising the step (step 2), which after applying the negative electrode slurry on the collector, drying in the negative electrode slurry containing the first particles and second particles, the first particles have a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and in that the sphericity measured by the particulate analyzer of 0.70 to 0.92, the artificial graphite, the weight ratio of the second particles with the first particles is from 1: 9 there is provided a method of producing a negative electrode: 1 to 1.
Effects of the Invention
[17]
A negative electrode in accordance with one embodiment of the invention the filling of the particle by using the second particles having a relatively high sphericity of the oxygen content is high the first particles with relatively low sphericity have a suitable weight ratio, the negative electrode active material layer can be made smoothly, the electrode adhesion strength can be improved. Accordingly, since prevented from particles of the negative electrode active material layers are eliminated from the current collector, the electrode easily, and the manufacturing process, the performance of the produced battery can be improved.
Mode for the Invention
[18]
Hereinafter, the present invention will be described to assist understanding of the present invention in more detail.
[19]
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.
[20]
Used herein it is to be used to describe only the exemplary embodiments, and are not intended to limit the present invention. Expression in the singular number include a plural forms unless the context clearly indicates otherwise.
[21]
In this specification, "it comprise", "comprising is" or "gajida" and terms are exemplary of characteristics, numbers, steps, components or geotyiji to be a combination thereof specify the presence, of one or more other characteristics or more or of numbers, steps, components, or the presence or possibility of combinations thereof and are not intended to preclude.
[22]
[23]
A negative electrode in accordance with one embodiment of the present invention is a current collector and a negative electrode comprising a negative active material layer disposed on the current collector, the negative electrode active material layer comprises first particles and second particles, said first particles have a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and the artificial graphite has a sphericity measured by the particulate analyzer of 0.70 to 0.92, the weight ratio of the second particles with the first particles is from 1: 1 to 1: can rails.
[24]
The first particle may include a first core and first shell.
[25]
The first core may be an artificial graphite. Artificial graphite, so lithium-absorbing ability is excellent, and when the first core is the artificial graphite has charge-discharge characteristics of the battery can be improved.
[26]
The average particle diameter (D of the first core 50 ) may be a 10㎛ to 20㎛, may be specifically 14㎛ to 18㎛. The average particle diameter (D of the first core 50 , if a) less than 10㎛, increase a side reaction of the electrolytic solution and the negative electrode active material layers, due to the increased surface area of the negative electrode active material layer, there is a problem that the electrode adhesion strength lowered. In addition, the average particle diameter (D of the first core 50 , if the) 20㎛ exceeded, there is a problem that the output performance of the negative electrode decreases.
[27]
The average particle diameter (D of the first core 50 with respect to) the present specification the average particle diameter (D in 50 ) may be defined as particle diameter at 50% of the particle based on the particle size distribution. The average particle diameter (D 50 ), for example, can be measured using a laser diffraction method (laser diffraction method). The laser diffraction method is generally possible to measure the particle diameter of approximately several mm from sub-micron (submicron) region, it is possible to obtain the results of high reproducibility and high degradability.
[28]
The first shell may be disposed on the first core. Specifically, the first shell may cover all or a part of the surface of the first core.
[29]
The first shell may comprise an oxide of the artificial graphite. An oxide of the artificial graphite may be any of the artificial graphite is oxidized generating compound, the oxygen content of an oxide of the artificial graphite may be higher than the oxygen content of the artificial graphite.
[30]
The thickness of the first shell may be in the 1nm to 200nm, may be 20nm to 100nm in detail. If the thickness of the first shell is less than 1nm, there is a lower electrode adhesion problem. In the case where more than the first thickness of the first shell 200nm, there is a problem due to the excessive increase in resistance which the performance of the battery decrease.
[31]
The average particle diameter (D of the first core 50 ) and the thickness of the first shell, but can be measured with a transmission electron microscope (TEM), is not limited thereto.
[32]
Measured through the particulate analyzer sphericity of the first particle it may be 0.94 to 0.98, may be specifically from 0.95 to 0.96. The sphericity can mean major axis than the minor axis of the first particle. The sphericity can be measured by frame-like particle analyzer (QICPIC-LIXELL, Sympatec GmbH). Specifically, determining the sphericity through a particulate analyzer distribution ratio from said first then derives a sphericity cumulative distribution of the first particles, the sphericity is large particles is equal to 50% in sphericity of the first particles, can do. The measuring method may be the same as the measuring method of sphericity, and a sphericity of the third particle in the second particle will be described later.
[33]
The manufacturing process of the first particles, a spheronization process proceeds, there is the sphericity can be obtained. Is less than the sphericity of the first particles to 0.94, the electrode adhesion strength by over-contoured surface of the first particle may cause low problem. Further, when the sphericity is greater than 0.98 of the first particle, so a large amount of the first particles is required to derive a high sphericity, it is possible to cause a problem that the manufacturing yield is lowered.
[34]
The average particle diameter (D of the first particles 50 ) may be a 10㎛ to 25㎛, may be 15㎛ to 20㎛ in detail. The average particle diameter (D of the first particles 50 when the) 10㎛ less, increase in a side reaction of the electrolytic solution and the negative electrode active material layers, due to the increased surface area of the negative electrode active material layer may cause a problem that the electrode adhesion strength lowered. In addition, the average particle diameter (D of the first particles 50 when the) exceeds the 25㎛, may cause a problem in which the output performance of the negative electrode decreases.
[35]
The tap density of the first particles (tap density) is 0.95g / cm 3 to 1.3g / cm 3 may be, specifically, 1.0g / cm 3 to 1.2g / cm 3 may be. The tap density of the first particle 0.95g / cm 3 may result in excessively by the curved surface of the lower electrode adhesion problems of the first particles is less than. Moreover, the tap density of the first particle 1.3g / cm 3 , because if the excess, a large amount of the first particles in order to obtain a high tap density requirements, may cause a problem that the manufacturing yield is lowered. The tap density is, for example, after the input of the first particles in the 100㎖ cylinder 40g, can be obtained by measuring the powder filling density after 1000 time tapping. However, it is not necessarily limited to the above method.
[36]
For the total weight of the first particles oxygen content may be 1200mg / kg to 2500mg / kg, it may be specifically 1500mg / kg to about 2000mg / kg. When the oxygen atom content is less than 1200mg / kg, it can cause lower electrode adhesion problem. Further, due to the case where the oxygen atom content of 2500mg / kg, greater than a resistance increase may be caused a problem that the cell performance. The oxygen content may be measured by elemental analysis (Elemental analysis), specifically, it can be measured via an oxygen nitrogen analyzer hydrogen (Hydrogen Oxygen Nitrogen Determinator) or TPO-MS equipment. However, it is not limited thereto.
[37]
The second particles may be artificial graphite. Artificial graphite, so lithium-absorbing ability is excellent, and the second particle can be improved charging and discharging characteristics of the battery case of the artificial graphite.
[38]
On the other hand, the second particle has a sphericity as measured by the particulate analyzer may be 0.70 to 0.92, may be specifically from 0.8 to 0.9. If the sphericity of the second particles is less than 0.70, because the surfaces of the second particles have an excessively curved shape, the electrode adhesion strength is lowered, which results can cause the electrode made difficult. Further, since when the sphericity of the second particles is greater than 0.92, a large amount of the second particles in order to obtain a high sphericity requirement, may cause a problem that the manufacturing yield is lowered.
[39]
The average particle diameter (D of the second particles 50 ) may be a 10㎛ to 25㎛, may be 15㎛ to 20㎛ in detail. The average particle diameter (D of the second particle 50 when the) 10㎛ less, increase in a side reaction of the electrolytic solution and the negative electrode active material layers, due to the increased surface area of the negative electrode active material layer may cause a problem that the electrode adhesion strength lowered. In addition, the average particle diameter (D of the second particle 50 when the) exceeds the 25㎛, may cause a problem in which the output performance of the negative electrode decreases. The average particle diameter (D of the second particle 50 Method of measuring) the average particle diameter (D of the first particle 50 is the same as the) measurement method.
[40]
Within the negative electrode active material, the weight ratio of the second particles with the first particles is from 1: 1 to 1: may be rails, specifically 1: 1 to 1: 4 may be, more specifically, from 1: 1 to 1 : can three days. When satisfied with the above weight ratio, the electrode adhesion strength can be improved.
[41]
Specifically, if the first particles or the second particles are used too much outside the above weight ratio, the particle is within the first and second particles, each of the negative electrode active material layer by the morphology of the pores is excessively present. In addition, because the first particles and the second can not be achieved smoothly filling (packing) between the particle, the negative electrode active material layer adhesion between the particles, the negative electrode active material layer and the adhesion between the whole house can be poor. On the other hand, the first particles and the second particles when used in appropriate mixing as the weight ratio, is relatively adjusting the amount of the second particles having a near first surface curved into particles and relatively to the spherical shape, the negative electrode active material layer my reduces the air gap, wherein the first particles and the second particles may be present in a smoothly meshed with each other. Thus, the electrode adhesion strength can be improved.
[42]
Relative to the total weight of the negative electrode active material layer, wherein the first particles and the total weight of the second particles may be a 95% to 99% by weight, and may be specifically 97% to 98% by weight.
[43]
In the negative electrode, the electrode adhesion may be any of 40gf / cm to about 90gf / cm, it can be specifically 44gf / cm to about 65gf / cm. The electrode adhesion can be measured by the following method. Emitted after the other to the negative electrode as 150mm × 10mm were fixed by using tape to a slide glass and a central portion 26mm × 76mm, throwing using UTM off the current collector 180 may be measured for peel strength. This obtained the average of the measured value by performing at least 5 times, and can derive the electrode adhesion.
[44]
The negative electrode active material layer may further include a conductive material. So long as it has suitable conductivity without causing chemical changes in the fabricated battery. The conductive material is not particularly limited, for example, graphite such as natural graphite or artificial graphite; Carbon black, acetylene black, Ketjen black, channel black, wave Ness black, carbon black and lamp black and thermal black; Conductive fibers such as carbon fibers and metallic fibers; Metal tubes, such as carbon nanotubes; Metal powders such as carbon, aluminum, nickel powder fluoro; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Poly is a conductive material such as phenylene derivative may be used.
[45]
The negative electrode active material layer may further include a binder. The binder is polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride (polyvinylidenefluoride), polyacrylonitrile (polyacrylonitrile), polymethyl methacrylate (polymethylmethacrylate), poly polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), alcohol sulfonated EPDM, and at least it can include any one selected a styrene-butadiene rubber (SBR), fluorine rubber, polyacrylic acid (poly acrylic acid), and combinations of hydrogen from the group consisting of a polymer substituted with Li, Na or Ca or the like, It may also include their various copolymers.
[46]
[47]
A cathode according to another embodiment of the present invention may differ from the embodiment described above in that there is one similar to the above-described example, the negative electrode active material layer may further include a third grain example. Therefore, to account for the differences hereinafter.
[48]
The third particles may comprise the batt and the second shell.
[49]
The second core may be a natural graphite. Natural graphite has higher amount of lithium bond, and the second may be the core improves the capacity of the battery case of natural graphite.
[50]
The average particle diameter (D of the second core 50 ) may be a 5㎛ to 25㎛, may be 9㎛ to 20㎛ in detail. The average particle diameter (D of the second core 50 , if a) less than 5㎛, increase a side reaction of the electrolytic solution and the negative electrode active material layers, due to the increased surface area of the negative electrode active material layer may cause a problem that the electrode adhesion strength lowered. In addition, the second average particle size (D of the core 50 If) exceeds the 25㎛, may cause a problem in which the output performance of the negative electrode decreases.
[51]
The second shell may be disposed on the second core. Specifically, the second shell may cover all or a part of a surface of the second core.
[52]
The second shell may comprise an oxide of a natural graphite. An oxide of the natural graphite may be any of the natural graphite is oxidized generating compound, the oxygen content of an oxide of the natural graphite may be higher than the oxygen content of the artificial graphite.
[53]
The thickness of the second shell may be in the 1nm to 200nm, may be 20nm to 100nm in detail. If the thickness of the second shell is less than 1nm, the electrode may be too low adhesion. In the case where the first thickness is greater than 200nm of the second shell, and the resistance may increase too much may cause problems in which a battery performance.
[54]
On the other hand, the third particles may be in the sphericity measured by the particulate analyzer of 0.94 to 0.98, may be specifically 0.96 to 0.97. Is less than the sphericity of the third particles to 0.94, it is possible to have an effect of improving the electrode adhesion strength deficiency. Further, since when the sphericity of the third particles are greater than 0.98, a large amount of the third particles in order to obtain a high sphericity requirement, may cause a problem that the manufacturing yield is lowered.
[55]
The average particle diameter (D in the third particles 50 ) may be a 7㎛ to 25㎛, may be 12㎛ to 20㎛ in detail. The average particle diameter (D in the third particles 50 is less than this) 7㎛, increase in a side reaction of the electrolytic solution and the negative electrode active material layers, due to the increased surface area of the negative electrode active material layer may cause a problem that the electrode adhesion strength lowered. In addition, the average particle diameter (D in the third particles 50 if) is exceeded 25㎛, may cause a problem in which the output performance of the negative electrode decreases.
[56]
The tap density of the third particles (tap density) is 1.0g / cm 3 to 1.2g / cm 3 may be, specifically, 1.05g / cm 3 to 1.15g / cm 3 may be. The tap density of the third particle 1.0g / cm 3 less than, the first electrode may be poor adhesion by over-contoured surface of a third particle. Moreover, the tap density of the third particle 1.2g / cm 3 , because if the excess, a large amount of the third particles in order to obtain a high tap density requirements, may cause a problem that the manufacturing yield is lowered. The tap density may be measured by the same method as the tap density measuring method of the first particles.
[57]
The first particle, the weight ratio of the second particles and the third particles 10 to 30: may be 10 to 30, specifically, 20 to 25: 40 to 80 may be 20 to 25: 50 to 60. When the above weight ratio satisfied, the filling of particles within the active material layer smooth yirueojyeoseo an electrode adhesion strength can be further improved.
[58]
Method of manufacturing a cathode according to another embodiment of the present invention is a negative electrode including a step of preparing a negative electrode slurry (the first step) and then coating the cathode slurry on a collector, drying (step 2) as regarding the production method, the negative electrode slurry containing the first particles and second particles, the first particles have a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and the artificial graphite has a sphericity measured by the particulate analyzer of 0.70 to 0.92, the weight ratio of the second particles with the first particles is from 1: 1 to 1: can rails. Here, the first particles and second particles comprising the above negative electrode slurry may be the same as that of the first particles and the second particles comprising the above-described negative electrode active material layer.
[59]
The first step may include the step of adding and mixing the first particle and the second particle in a solvent (1-1 phase). The solvent may be daily for one commonly used in the art, may be particularly distilled water. In the second step 1-1, the first can be mixed with further addition of the binder with the first particles and the second particles. Alternatively, in Step 1-1, the first particles and the mixture may be further added to the conductive material and a binder with a second grain. The conductive material and binder may be the same as the conductive material and a binder which may comprise the above-described negative electrode active material layer.
[60]
The negative electrode slurry may further include a third particle. Specifically, the in operation 1-1, the first may be added and mixed the third particles with a first particle and a second particle in the solvent. Here, the third particles comprising the above negative electrode slurry may be the same as the third particles comprising the above-described negative electrode active material layer.
[61]
[62]
A secondary battery according to still another embodiment of the present invention may comprise a separator, and an electrolyte interposed between the negative electrode, a positive electrode, the positive electrode and the negative electrode, and the negative electrode is a one cathode according to any one of the embodiments described above can.
[63]
Membrane as separates the cathode and the anode, and by providing a moving path of the lithium ions, so long as it is in a conventional secondary battery using the separator can be used without particular limitation, and, in particular, yet low resistance against ion mobility of the electrolyte electrolyte humidification ability is excellent it is desirable. Specifically, the porous polymer film, such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymers and ethylene / methacrylate, the porous polymer made of a polyolefin-based polymer such as copolymer film thereof the two or more layers of the multilayer structure may be used. In addition there is a porous non-woven fabric in a conventional, such as high melting point glass of the fiber, polyethylene terephthalate fiber, such as non-woven fabric may be used. In addition, there may also be a membrane coating containing a ceramic component or a high molecular material used for the heat resistance or mechanical strength secured, may optionally be used in a single layer or multi-layer structure.
[64]
The electrolyte may be an electrolyte in a lithium secondary battery manufacturing usable organic liquid electrolyte, an inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten-type inorganic electrolyte or the like, not limited to these.
[65]
Specifically, the electrolyte may include a nonaqueous organic solvent and a metal salt.
[66]
In the non-aqueous organic solvents, e.g., N- methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyl lactone, 1,2-dimethoxy ethane, tetrahydroxy Franc (franc), 2- methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester, trimethoxy methane, dioxolane derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ether, fatigue Nafion the aprotic organic solvent such as methylmethacrylate, ethyl propionate may be used.
[67]
In particular, as the carbonate-based organic solvent, a cyclic carbonate of ethylene carbonate and propylene carbonate of which it may preferably be used because good dissociation of lithium salt increases the dielectric constant is used as the organic solvent of high viscosity, such a cyclic carbonate, dimethyl carbonate and diethyl carbonate such as low viscosity, the use of a mixture of low dielectric constant linear carbonate in a suitable ratio can make the electrolyte having a high conductivity may be used more preferably.
[68]
The metal salt may be a lithium salt, the lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for example, is in the lithium salt anion F - , Cl - , I - , NO 3 - , N (CN ) 2 - , BF 4 - , ClO 4 - , PF 6 - , (CF 3 ) 2 PF 4 - , (CF 3 ) 3 PF 3 - , (CF 3 ) 4 PF 2 - , (CF 3 ) 5 PF - , (CF 3 ) 6 P - , CF 3 SO 3 - , CF 3 CF 2 SO 3 - , (CF 3 SO 2 ) 2 N - , (FSO 2 ) 2 N - , CF 3 CF 2 (CF 3 ) 2 CO - , (CF 3 SO 2 ) 2 CH - , (SF 5 ) 3 C - , (CF 3 SO 2 ) 3 C - , CF 3 (CF 2 ) 7 SO 3 - , CF 3 CO 2 - , CH 3 CO 2 - , SCN - , and (CF 3 CF 2 SO 2 ) 2 N - may be used one selected from the group consisting of.
[69]
The electrolyte improves life characteristics of the battery in addition to the electrolyte composition, the battery capacity is decreased inhibition, for the purpose of improving the discharge capacity of the battery, for example, difluoromethyl halo alkylene carbonate compound, a pyridine such as ethylene carbonate, tri ethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n- glyme (glyme), hexamethyl phosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N- substituted oxazolidinone, N, N- substituted already Jolly Dean, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, or more than one type of additive, such as aluminum trichloride may be further included.
[70]
[71]
In accordance with another embodiment of the present invention, there is provided a battery pack including the battery module, and it comprises a unit cell, the secondary battery. The battery module and the battery pack, high-capacity, high-rate controlling properties and it comprises a secondary battery having the recital characteristics, electric vehicles, hybrid electric vehicles, plug-in middle- or large-sized device is selected from the group consisting of a hybrid electric vehicle and the power storage system for in can be used as a power source.
[72]
[73]
Hereinafter, one present preferred embodiment to help understanding of the invention, the examples are apparent according to the intended well as the scope and spirit the scope those skilled in the art will that various changes and modifications within the possible of the substrate for illustrating the present description, It not included in the claims, these changes and modifications to the appended granted.
[74]
[75]
Examples and Comparative Examples
[76]
[77]
Preparation 1: Preparation of first particles
[78]
The average particle diameter (D 50 ) in a pitch binder is 7㎛ artificial graphite (pitch binder) and the like to a mixture of the back, for 2 hours at 3000 ℃ heat treatment, the average particle diameter (D 50 ) is 17㎛ the secondary structure of the artificial graphite particles the hayeotda jejo. Subsequently by screen rotary spheronization using the equipment, the spherical artificial graphite, it was prepared in a preliminary particle.
[79]
The preliminary particles oxygen atmosphere, 400 ℃, 0.1MPa pressure, 60m 3 by the oxidation treatment to the / h of air flow conditions to prepare a first particle including a first core and first shell.
[80]
In the producing the first particles, the average particle diameter (D in the first core 50 is a) 16.86㎛, the thickness of the first shell was 70nm. The average particle diameter (D in the first core 50 ) is the particle size was measured by the analyzer (PSD), a thickness of the first shell was determined by transmission electron microscopy (TEM). In addition, was the sphericity of the resulting first particles is 0.96 as measured by the particle shape analyzer.
[81]
[82]
Preparation 2: Preparation of second particles
[83]
The average particle diameter (D 50 ) is the rear 7㎛ the artificial graphite is mixed as a binder and the pitch (pitch binder), and heat treated for 2 hours at 3000 ℃, the average particle diameter (D 50 ) of the second secondary particle structure in which 19㎛ It was prepared in the particles. In addition, it was a sphericity of the obtained particles is 0.89 second as measured by the particle shape analyzer.
[84]
Preparation Example 3: Preparation of a third grain
[85]
The average particle diameter (D 50 ) of the natural graphite is 7㎛ pitch binder (binder pitch) and the like to a mixture of the back, for 2 hours at 3000 ℃ heat treatment, the average particle diameter (D 50 ) is 16㎛ the secondary structure of the artificial graphite particles It was prepared. Then, using a rotary spheronization equipment, by spheroidizing the natural graphite, to prepare a preliminary particle.
[86]
The preliminary particles oxygen atmosphere, 400 ℃, 0.1MPa pressure, 60m 3 by the oxidation treatment to the / h of air flow condition, the third particle was prepared comprising a second core and the second shell.
[87]
In the manufacturing the third particle, the average particle diameter (D of the second core 50 is a) 15.80㎛, the thickness of the second shell was 100nm. The average particle diameter (D of the second core 50 ) is the particle size was measured by the analyzer (PSD), the thickness of the second shell was determined by transmission electron microscopy (TEM). In addition, was the sphericity of the resulting third particles of 0.97 as measured by the particle shape analyzer.
[88]
[89]
With respect to the Preparation Example 1 to the first particles, second particles, and third particles, each prepared from 3, shown in Table 1 to measure a tap density, oxygen content. Each measurement method is as follows.
[90]
[91]
Tap Density
[92]
The first particles, second particles, after the input of the first particles, the particles 3 in a cylinder of 40g 100㎖ respectively, were measured for the powder filling density after 1000 time tapping.
[93]
[94]
Oxygen atom content
[95]
Use ONH835 Analyzer equipment, wherein the first particles and second particles, the third particles was measured for an oxygen atom content for each sample 2mg.
[96]
[97]
TABLE 1
Particles with a mean particle size (D 50 ) (㎛) Sphericity Tap density (g / cm 3 ) Oxygen atom content (mg / kg)
First particles 17 0.96 1.1 1800
Second particles 19 0.89 0.9 244
The third particle 16 0.97 1.14 2200

[98]
[99]
Example 1: Preparation of a negative electrode
[100]
The first particles 1g and Preparation Example 2 of the mouse as carboxymethylcellulose as active material particles, carbon black, a binder, a conductive material made of a second grain 9g and styrene-butadiene rubber prepared in (SBR) prepared in Preparative Example 1 95.3 : 1.0: 1.2 was added and mixed in distilled water to a weight ratio of 2.5 to prepare a negative electrode slurry mixture of solids of 45%. Wherein the negative electrode slurry throughout the copper collector having a thickness of 260mg 20㎛ / 25cm 2 by coating and dried to prepare a pre-loading of the electrode. Temperature at this time, the circulated air was 70 ℃. Then, the pre-electrode rolled (roll press) to and was dried in a vacuum oven at 130 ℃ for 12 hours, 1.4875cm 2 emitted by other coin cell size to thereby prepare a negative electrode.
[101]
[102]
Example 2: Preparation of a negative electrode
[103]
Example instead of the active material particles 1, except for using the first active material particles made of particles to the second particles 7g prepared in 3g and Preparation Example 2 was prepared in Preparative Example 1 to prepare a negative electrode in the same manner.
[104]
[105]
Example 3: Preparation of a negative electrode
[106]
Embodiment the active material particle of Example 1 instead of, for using the active material particles composed of the third grain 2g prepared in Preparative Example 1, the first particles 2g, a second particle 6g, Preparation Example 3 prepared in Preparation Example 2 manufactured by except that, the negative electrode was prepared in the same manner.
[107]
[108]
Comparative Example 1: Preparation of a negative electrode
[109]
Embodiment, instead of the active material particles 1, except that the first active material particles consisting of only one particle 10g prepared in Preparative Example 1, a negative electrode was prepared in the same manner.
[110]
[111]
Comparative Example 2: Preparation of a negative electrode
[112]
Embodiment, instead of the active material particles 1, except that the first active material particles composed of only two particles 10g prepared in Preparative Example 2, a negative electrode was prepared in the same manner.
[113]
[114]
Comparative Example 3: Preparation of a negative electrode
[115]
Example instead of the active material particles 1, except for using the electrode active material particles, the first consisting of two particles 3g prepared first particles 7g and the preparation prepared in Preparation Example 1 in Example 2, to thereby prepare a negative electrode in the same manner.
[116]
[117]
Comparative Example 4: Preparation of a negative electrode
[118]
Embodiment, instead of the active material particles in Example 1, except that the active material particles composed of a second particle 9.8g prepared in Preparative Example 1, 0.2g of the first particle and the preparation prepared in Example 2 and is, produce a negative electrode in the same manner It was.
[119]
[120]
Experimental Example 1: Adhesion Evaluation electrode
[121]
Examples 1 to 3 and Comparative Examples with respect to one to four negative electrode each, and then emitted the other the negative electrode by 10mm × 150mm was fixed with a tape to a slide glass central portion 26mm × 76mm, using the UTM off the anode current collector tipping 180 ° peel strength was measured. The evaluation was defined as the average value by measuring five or more peel strength. To this it is shown in Table 2 below.
[122]
[123]
Experimental Example 2: Evaluation Cycle characteristics
[124]
Examples 1 to 3 and Comparative Examples 1 to 4 with respect to the negative electrode each, by filling until 4.25V with a constant current (CC) of 0.8C at 25 ℃, and then charged to a constant voltage (CV) charging current is 0.005 C (cut-off current) was subjected to the charging of the first time until the. This was then discharged until 2.5V with constant current (CC) of 0.8C, and then allowed to stand for 20 minutes. Conducted for one to 50 times of repeated cycles, the capacity retention rate were evaluated, the results are shown in Table 2 below.
[125]
[126]
The results of the experimental examples 1 and 2 are shown in Table 2 below.
[127]
TABLE 2
Electrode adhesion (gf / cm) Capacity retention ratio @ 50 cycles (%)
Example 1 43 90
Example 2 46 89
Example 3 63 93
Comparative Example 1 41 88
Comparative Example 2 17 81
Comparative Example 3 41 88
Comparative Example 4 19 83

[128]
Accordingly, the first particles and the second particles to 1: 9, 1: Using a 1: negative electrode of Example 1 and Example 2 used in 2.33 as the first particles, second particles, and a third particle 1: 3 the exemplary electrode adhesion of the negative electrode of example 3, 1: it can be seen that the electrode is higher than the adhesive strength of the negative electrode of Comparative example 1-4 that satisfy the weight ratio is outside the range of 9: 1 to 1. Further, the capacity retention ratio of Examples 1 to 3 also can be seen that higher than Comparative Example 1-4.
[129]
Further, the embodiment includes a third particle in an appropriate amount Example 3, it can be confirmed that Example 1 and a high adhesive strength and an electrode capacity maintenance rate compared to the second.

Claims
[Claim 1]
In the current collector and a negative electrode comprising a negative active material layer disposed on the current collector, the negative electrode active material layer comprises first particles and second particles, the first particles have a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and in that the sphericity measured by the particulate analyzer of 0.70 to 0.92, the artificial graphite, the weight ratio of the second particles with the first particles is from 1: 1 to 1: 9, the cathode.
[Claim 2]
The method according to claim 1, the average particle diameter (D of the first particles 50 ) is the cathode 10㎛ to 25㎛.
[Claim 3]
The method according to claim 1, the average particle diameter (D of the first core 50 is 10㎛ 20㎛ to the cathode).
[Claim 4]
The method according to claim 1, the cathode a thickness of the first shell is 1nm to 200nm.
[Claim 5]
The method according to claim 1, wherein the tap density of the first particles is 0.95g / cm 3 to 1.3g / cm 3 of a negative electrode.
[Claim 6]
The method according to claim 1, the average particle diameter (D of the second particles 50 ) is the cathode 10㎛ to 25㎛.
[Claim 7]
The method according to claim 1, the cathode is an oxygen atom content for the total weight of 1200mg / kg to about 2500mg / kg of the first particles.
[Claim 8]
The method according to claim 1, the cathode is the total weight of the second particles with the first particles relative to the total weight of the negative electrode active material layer is 95% to 99% by weight.
[Claim 9]
The method according to claim 1, wherein the negative electrode active material layer further includes a third particle, said third particle is, the batt containing the natural graphite; And the second core is arranged on the first 2 includes a shell, a sphericity as measured by the particulate analyzer of 0.94 to 0.98 a cathode comprising an oxide of the natural graphite.
[Claim 10]
The method according to claim 9, wherein the first particles and the second particles and the weight ratio of the third particles 10 to 30: the cathode 10 to 30: 40 to 80.
[Claim 11]
The method according to claim 9, the average particle diameter (D in the third particles 50 ) is the cathode 7㎛ to 25㎛.
[Claim 12]
The method according to claim 9, wherein the second average particle size (D of the core 50 ) is the cathode 5㎛ to 25㎛.
[Claim 13]
The method according to claim 9, wherein the negative electrode thickness of the second shell is 1nm to 200nm.
[Claim 14]
The method according to claim 9, the tap density of the third particle is 1.0g / cm 3 to 1.2g / cm 3 of a negative electrode.
[Claim 15]
In the method for manufacturing a negative electrode comprising the steps of: preparing a negative electrode slurry (the first step) and then coating the cathode slurry on a collector, drying (second step), the negative electrode slurry is first particles and a second particle, the first particle has a first core including the artificial graphite; And the first is disposed on the core comprises a first shell including an oxide of the artificial graphite, and the sphericity of the first particles measured by the particle shape analyzer of 0.94 to 0.98, wherein the second particles are the and in that the sphericity measured by the particulate analyzer of 0.70 to 0.92, the artificial graphite, the weight ratio of the second particles with the first particles is from 1: 1 to 1: 9 the method of producing a negative electrode.