CN110431697B - Method for preparing slurry composition for secondary battery positive electrode, positive electrode prepared by the method, and lithium secondary battery comprising the positive electrode - Google Patents

Method for preparing slurry composition for secondary battery positive electrode, positive electrode prepared by the method, and lithium secondary battery comprising the positive electrode Download PDF

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CN110431697B
CN110431697B CN201880019062.3A CN201880019062A CN110431697B CN 110431697 B CN110431697 B CN 110431697B CN 201880019062 A CN201880019062 A CN 201880019062A CN 110431697 B CN110431697 B CN 110431697B
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positive electrode
active material
electrode active
dispersion
secondary battery
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CN110431697A (en
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安炳勋
刘兴植
权桂缗
崔相勋
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LG Energy Solution Ltd
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Abstract

The present invention relates to a method of preparing a slurry composition for a secondary battery positive electrode, a secondary battery positive electrode prepared using the method, and a lithium secondary battery including the positive electrode, the method including: a step of mixing a lithium iron phosphate-based positive electrode active material, a dispersant and a solvent to prepare a positive electrode active material pre-dispersion, and a step of further mixing a conductive agent, a binder and an additional solvent with the positive electrode active material pre-dispersion to prepare a slurry for a positive electrode.

Description

Method for preparing slurry composition for secondary battery positive electrode, positive electrode prepared by the method, and lithium secondary battery comprising the positive electrode
Cross Reference to Related Applications
This application claims priority from korean patent application No. 10-2017-0036335 filed at 22.3.2017 in the korean intellectual property office and korean patent application No. 10-2018-0033151 filed at 22.3.22.2018 in the korean intellectual property office, the disclosures of which are incorporated herein by reference in their entireties.
Technical Field
The present invention relates to a method of preparing a slurry composition for a secondary battery positive electrode, a secondary battery positive electrode prepared using the method, and a lithium secondary battery including the positive electrode.
Background
As the technical development and demand for mobile devices increase, the demand for secondary batteries as an energy source has significantly increased. Among these secondary batteries, lithium secondary batteries having high energy density, high voltage, long cycle life and low self-discharge rate have been commercialized and widely used.
As a main component of a cathode active material of a conventional lithium secondary battery, a lithium-containing cobalt oxide (LiCoO) having a high operating voltage and excellent capacity characteristics has been used2) Among them, lithium-containing cobalt oxides have very poor thermal properties due to an unstable crystal structure caused by lithium deintercalation and are expensive, so there is a limitation in that it is difficult to mass-produce lithium secondary batteries.
Recently, lithium iron phosphate (LiFePO)4) The base compound is attracting attention as a positive electrode active material for a lithium secondary battery, which not only has better high-temperature stability than cobalt, but also is inexpensive, has a voltage of-3.5V with respect to lithium, and has about 3.6g/cm3And a theoretical capacity of about 170 mAh/g.
The lithium iron phosphate-based cathode active material is a cathode active material that is structurally very stable, but has disadvantages in that electron conductivity and ion conductivity are low. Therefore, the lithium iron phosphate-based positive electrode active material was used in the following manner: the electron conductivity is improved by coating the surface of the lithium iron phosphate-based cathode active material with carbon, and the ion conductivity is improved by reducing the particle size of the lithium iron phosphate-based cathode active material.
However, as the particle diameter of the positive electrode active material is decreased, the specific surface area is increased and the aggregation of the positive electrode active material particles is severe, so that there is a limitation in that the dispersion is difficult.
Disclosure of Invention
Technical problem
An aspect of the present invention provides a method of preparing a slurry composition for a secondary battery positive electrode, which can suppress aggregation of a lithium iron phosphate-based positive electrode active material having a reduced particle diameter, can improve dispersibility, can improve fluidity by reducing viscosity, and can increase a final solid content, a positive electrode for a secondary battery prepared using the method, and a lithium secondary battery including the positive electrode.
Technical scheme
According to an aspect of the present invention, there is provided a method of preparing a slurry composition for a positive electrode of a secondary battery, the method including: mixing a lithium iron phosphate-based positive active material, a dispersant and a solvent to prepare a positive active material pre-dispersion; and further mixing a conductive agent, a binder and an additional solvent with the positive active material pre-dispersion to prepare a slurry for a positive electrode.
According to another aspect of the present invention, there is provided a positive electrode active material pre-dispersion composition comprising a lithium iron phosphate-based positive electrode active material, a dispersant, and a solvent, wherein the lithium iron phosphate-based positive electrode active material is in an average particle diameter (D)50) Less than 1 μm, and a viscosity of 2,000cps to 20,000cps (25 ℃).
According to another aspect of the present invention, there is provided a slurry composition for a secondary battery positive electrode, which includes a conductive agent and a binder, in addition to the above-described positive electrode active material pre-dispersion composition.
According to another aspect of the present invention, there is provided a positive electrode for a secondary battery prepared by using the slurry composition for a positive electrode for a secondary battery, and a lithium secondary battery including the positive electrode.
Advantageous effects
According to the present invention, the dispersion particle diameter can be reduced by suppressing aggregation of a lithium iron phosphate-based positive electrode active material having a reduced particle diameter and improving dispersibility; the fluidity can be improved by reducing the viscosity of the positive active material pre-dispersion and the positive electrode slurry, thereby improving the processability; and the final solids content can be increased.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate preferred embodiments of the invention by way of example and together with the detailed description of the invention given below serve to explain the principles of the invention.
Fig. 1 is a graph showing the shear viscosity of slurry compositions for positive electrodes of examples 1 to 3 and comparative examples 1 and 2;
fig. 2 is a graph showing the fluidity of slurry compositions for positive electrodes of examples 1 to 3 and comparative examples 1 and 2; and is
Fig. 3 is a graph showing adhesion of positive electrodes prepared by using the slurry compositions for positive electrodes of examples 1 to 3 and comparative examples 1 and 2.
Detailed Description
Hereinafter, the present invention will be described in more detail in order to more clearly understand the present invention. In this case, it will be understood that the words or terms used in the present specification and claims should not be construed as meanings defined in a general dictionary, and it should be further understood that the words or terms should be construed as having meanings consistent with their meanings in the related technical context and technical idea of the present invention on the basis of the principle that the inventor can appropriately define the meanings of the words or terms to best explain the present invention.
The method for preparing the slurry composition for a secondary battery positive electrode according to the present invention comprises: mixing a lithium iron phosphate-based positive active material, a dispersant and a solvent to prepare a positive active material pre-dispersion; and further mixing a conductive agent, a binder and an additional solvent with the positive active material pre-dispersion to prepare a slurry for a positive electrode.
The lithium iron phosphate-based cathode active material is a cathode active material that is structurally very stable, but has disadvantages in that electron conductivity and ion conductivity are low. Therefore, the lithium iron phosphate-based positive electrode active material was used in the following manner: the electron conductivity is improved by coating the surface of the lithium iron phosphate-based cathode active material with carbon, and the ion conductivity is improved by reducing the particle size of the lithium iron phosphate-based cathode active material.
In general, as the particle diameter of the lithium iron phosphate-based positive electrode active material decreases, the particles of the positive electrode active material undergo severe aggregation, and thus dispersion is difficult.
Therefore, in the present invention, since the slurry for a positive electrode is prepared by further mixing the conductive agent and the binder with the positive electrode active material pre-dispersion after the positive electrode active material pre-dispersion is first prepared by pre-dispersing the lithium iron phosphate-based positive electrode active material using the dispersant, the problem of dispersibility of the lithium iron phosphate-based positive electrode active material having a reduced particle size is solved.
First, in the preparation of a pre-dispersion of a positive electrode active material, a lithium iron phosphate-based positive electrode active material and a dispersant are mixed in a solvent. During the preparation of the positive electrode active material pre-dispersion, it is necessary to mix a dispersant together, wherein a commonly used dispersant may be used as the above dispersant, but Hydrogenated Nitrile Butadiene Rubber (HNBR) is more preferably used, although it is not necessarily limited thereto.
Hydrogenated nitrile rubber (HNBR) refers to rubber in which the double bond originally contained in nitrile rubber (NBR) is changed to a single bond by hydrogenation of the nitrile rubber (NBR).
The hydrogenated nitrile rubber (HNBR) dispersant comprises repeating units derived from Acrylonitrile (AN) in AN amount of from 20 to 50 wt%, more preferably from 25 to 45 wt%, and most preferably from 30 to 40 wt%, based on the total weight of the hydrogenated nitrile rubber (HNBR).
The Hydrogenated Butadiene (HBD) ratio in the hydrogenated nitrile rubber (HNBR) dispersant may satisfy the following equation 1.
[ equation 1]
1 (%)% by weight of HBD/(% by weight of BD + HBD) × 100 ≦ 30 (%)
In equation 1, the HBD wt% is the weight% of repeating units derived from Hydrogenated Butadiene (HBD) based on the total weight of the hydrogenated nitrile rubber (HNBR), and the (BD + HBD) wt% is the weight% of repeating units derived from Butadiene (BD) and repeating units derived from Hydrogenated Butadiene (HBD) based on the total weight of the hydrogenated nitrile rubber (HNBR).
The Hydrogenated Butadiene (HBD) ratio of equation 1 may more preferably be in the range of 5% to 25%, and may most preferably be in the range of 10% to 25%.
In the case where the Hydrogenated Butadiene (HBD) ratio of equation 1 is less than 1%, since the adhesion to the surface of the carbon coating layer coated on the surface of the positive electrode active material is reduced, wetting is not well performed during the preparation of the dispersion, and thus, the dispersibility may be reduced. In the case where the Hydrogenated Butadiene (HBD) ratio is more than 30%, the solubility of the hydrogenated nitrile rubber in the dispersion medium may be reduced.
The hydrogenated nitrile rubber (HNBR) dispersant may have a weight average Molecular Weight (MW) of 10,000 to 700,000, more preferably 25,000 to 600,000, and most preferably 200,000 to 400,000.
The content of the dispersant may be 0.8 to 1.5 parts by weight, more preferably 0.8 to 1.3 parts by weight, and most preferably 1 to 1.2 parts by weight, based on 100 parts by weight of the lithium iron phosphate-based positive electrode active material. In the case where the content of the dispersant is less than 0.8 parts by weight, viscosity may significantly increase because the surface area of the cathode active material increases with the decrease in the dispersed particle diameter and the dispersant cannot sufficiently surround the increased surface of the cathode active material, while in the case where the content of the dispersant is more than 1.5 parts by weight, it may be a cause of the increase in viscosity because there is an excessive amount of the dispersant in the solvent that is not adsorbed on the surface of the cathode active material.
The lithium iron phosphate-based positive active material may be represented by formula 1 below.
[ formula 1]
Li1+a1Fe1-x1M1 x1PO4-b1Ab1
In formula 1, M1Is at least one selected from the group consisting of manganese (Mn), nickel (Ni), cobalt (Co), copper (Cu), scandium (Sc), titanium (Ti), chromium (Cr), vanadium (V) and zinc (Zn), A is at least one selected from the group consisting of sulfur (S), selenium (Se), fluorine (F), chlorine (Cl) and iodine (I), -0.5<a1<0.55，0≤x1<0.5, and 0. ltoreq. b 1. ltoreq.0.1.
For example, the lithium iron phosphate-based positive active material may be LiFePO4. Also, in order to improve electron conductivity of the lithium iron phosphate-based cathode active material, the surface of the particles may be coated with a carbon-based material.
The solvent may be a solvent commonly used in the art, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and any one thereof or a mixture of two or more thereof may be used, for example, N-methylpyrrolidone (NMP) may be used.
In the preparation of the positive electrode active material pre-dispersion, the lithium iron phosphate-based positive electrode active material, the dispersant and the solvent are added, and then dispersion may be performed by stirring or grinding. The stirring or milling may be carried out according to conventional stirring or milling methods, and may be carried out, for example, by using a stirring or milling apparatus: for example a homogenizer, a bead mill, a ball mill, a basket mill, an attritor, a universal stirrer, a clean mixer or a TK mixer. The dispersion may be more preferably carried out by a homogenizer and a bead mill.
In the preparation of the positive electrode active material pre-dispersion, dispersion may be performed so as to make the average particle diameter (D) of the lithium iron phosphate-based positive electrode active material contained in the positive electrode active material pre-dispersion50) Less than 1 μm. The lithium iron phosphate-based positive electrode active material contained in the positive electrode active material pre-dispersion prepared according to the embodiment of the present invention may be dispersed to an average particle diameter (D)50) Primary particles of less than 1 μm, more preferably less than 0.9 μm, and most preferably less than 0.8 μm.
The preparation of the positive active material pre-dispersion may be performed such that the viscosity of the positive active material pre-dispersion is from 2,000cps to 20,000cps (25 ℃), more preferably from 9,000cps to 14,000cps (25 ℃), and most preferably from 10,000cps to 13,500cps (25 ℃).
In the present invention, since the positive electrode active material pre-dispersion is prepared by pre-dispersing the lithium iron phosphate-based positive electrode active material having a reduced particle size with the dispersant, the dispersibility of the lithium iron phosphate-based positive electrode active material having a reduced particle size can be significantly improved, and the viscosity can be reduced at the same time.
Specifically, the positive electrode active material pre-dispersion composition prepared according to the embodiment of the present invention as described above includes a lithium iron phosphate-based positive electrode active material, a dispersant, and a solvent, wherein the lithium iron phosphate-based positive electrode active material may have an average particle diameter (D)50) Less than 1 μm primary particles, and the viscosity may be from 2,000cps to 20,000cps (25 ℃).
Next, a conductive agent, a binder, and an additional solvent are further mixed with the positive active material pre-dispersion to prepare a slurry for a positive electrode.
The conductive agent is used to provide conductivity to the electrode, wherein any conductive agent may be used without particular limitation so long as it has electron conductivity without causing adverse chemical changes in the battery. Specific examples of the conductive agent may be at least one selected from the group consisting of: graphite, such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; powders or fibers of metals such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides such as titanium oxide; or a conductive polymer such as a polyphenylene derivative. The content of the conductive agent may be 1 to 30% by weight, based on the total weight of the slurry composition for a positive electrode.
The binder improves adhesion between particles of the positive electrode active material and adhesion between the positive electrode active material and the collector. Specific examples of the binder may be at least one selected from the group consisting of: polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubber or a copolymer thereof. The binder may be contained in an amount of 1 to 30 wt% based on the total weight of the slurry composition for a positive electrode.
Similar to the positive active material pre-dispersion, the additional solvent may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, any one of them or a mixture of two or more of them may be used, for example, N-methylpyrrolidone (NMP) may be used, and the same solvent as that in the positive active material pre-dispersion composition may be used.
In the preparation of the slurry for a positive electrode, a positive electrode active material of a lithium composite transition metal oxide represented by the following formula 2 may be mixed in addition to the lithium iron phosphate-based positive electrode active material contained in the positive electrode active pre-dispersion.
[ formula 2]
Lia2Ni1-x2-y2Cox2M3 y2M4 z2O2
In formula 2, a2 is more than or equal to 1.0 and less than or equal to 1.5, 0<x2≤0.2，0<y2≤0.2，0≤z2≤0.1，M3Is at least one selected from the group consisting of Mn and aluminum (Al), and M4Is at least one selected from the group consisting of barium (Ba), calcium (Ca), zirconium (Zr), Ti, magnesium (Mg), tantalum (Ta), niobium (Nb), and molybdenum (Mo).
The lithium iron phosphate-based positive active material and the positive active material of the lithium composite transition metal oxide represented by formula 2 may be mixed in a weight ratio of 1:99 to 40:60, more preferably 2:98 to 30:70, and most preferably 5:95 to 15: 85.
Also, when preparing the slurry for a positive electrode, the dispersant may be further mixed with the positive active material pre-dispersion, and in addition, other additives may also be mixed to achieve desired properties of the electrode.
As described above, since the positive electrode active material pre-dispersion is prepared by pre-dispersing the lithium iron phosphate-based positive electrode active material with the dispersant, and the slurry for a positive electrode is prepared by mixing the conductive agent and the binder with the positive electrode active material pre-dispersion, the dispersibility of the lithium iron phosphate-based positive electrode active material is improved, the viscosity of the slurry for a positive electrode is reduced and the fluidity is improved, thereby improving the workability, and the solid content of the final positive electrode slurry may be increased. Also, the more the dispersibility of the lithium iron phosphate-based positive electrode active material is improved, the more the positive electrode adhesion can be improved, and thus, since the adhesion is improved, the amount of the binder in the positive electrode slurry composition can be reduced as compared with the conventional case.
Also, the present invention provides a positive electrode for a secondary battery prepared by using the above slurry composition for a positive electrode for a secondary battery.
Specifically, the positive electrode includes a positive electrode collector and a positive electrode active material layer that is provided on at least one surface of the positive electrode collector and is formed by using the above slurry composition for a positive electrode.
The positive electrode collector is not particularly limited as long as it has conductivity without causing adverse chemical changes in the battery, and, for example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium, silver, or the like may be used. Also, the thickness of the positive electrode current collector may be generally 3 to 500 μm, and in addition, minute irregularities may be formed on the surface of the current collector to improve the adhesion of the positive electrode active material. The positive electrode current collector may be used in various shapes, for example, in the shape of a film, a sheet, a foil, a mesh, a porous body, a foam, a nonwoven body, or the like.
The positive electrode may be prepared according to a conventional method for preparing a positive electrode, except that the above slurry composition for a positive electrode is used. Specifically, the slurry composition for a positive electrode is coated on a positive electrode collector, and then the positive electrode can be prepared by drying and rolling the coated positive electrode collector.
Also, as another method, the above slurry composition for a positive electrode may be on a separate support, and then the film separated from the support is laminated on a positive electrode current collector, thereby preparing a positive electrode.
Further, according to another embodiment of the present invention, there is provided an electrochemical device including the positive electrode. The electrochemical device may be specifically a battery or a capacitor, and may be, for example, a lithium secondary battery.
The lithium secondary battery specifically includes a positive electrode, a negative electrode disposed opposite to the positive electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is as described above. Also, the lithium secondary battery may further optionally include a battery case accommodating the electrode assembly of the cathode, the anode and the separator, and a sealing member sealing the battery case.
In the lithium secondary battery, the anode includes an anode current collector and an anode active material layer provided on the anode current collector.
The anode current collector is not particularly limited as long as it has high conductivity without causing adverse chemical changes in the battery, and, for example, copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium, silver, or the like, and aluminum-cadmium alloys can be used. Also, the thickness of the anode current collector may be generally 3 μm to 500 μm, and, similar to the cathode current collector, minute irregularities may be formed on the surface of the current collector to improve the adhesion of the anode active material. The negative electrode current collector may be used in various shapes, for example, in the shape of a film, a sheet, a foil, a mesh, a porous body, a foam, a nonwoven body, or the like.
The anode active material layer selectively includes a binder and a conductive agent in addition to the anode active material.
As the negative electrode active material, a compound capable of reversibly intercalating and deintercalating lithium may be used. Specific examples of the anode active material may be: carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; a metal substance that can be alloyed with lithium, such as silicon (Si), aluminum (Al), tin (Sn), lead (Pb), zinc (Zn), bismuth (Bi), indium (In), magnesium (Mg), gallium (Ga), cadmium (Cd), a Si alloy, a Sn alloy, or an Al alloy; can be doped with lithium or undoped metal oxides, e.g. SiOβ(0<β<2)、SnO2Vanadium oxide and lithium vanadium oxide; or a composite comprising a metal substance and a carbonaceous material, such as a Si-C composite or a Sn-C composite, and either one or a mixture of two or more thereof may be used. Also, a metallic lithium thin film may be used as the negative active material. In addition, both low crystalline carbon and high crystalline carbon can be used as the carbon material. Typical examples of the low crystalline carbon may be soft carbon and hard carbon, and typical examples of the high crystalline carbon may be irregular, plate-like, flake-like, spherical or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesophase carbon microsphere, mesophase pitch and high temperature sintered carbon, such as coke derived from petroleum or coal tar pitch.
Also, the binder and the conductive agent may be the same as those previously described in the positive electrode.
The anode active material layer may be prepared by the following process: dissolving or dispersing an optional binder and a conductive agent and a negative electrode active material in a solvent to prepare a composition for forming a negative electrode, coating the composition on a negative electrode current collector, and drying the coated negative electrode current collector; or can be prepared by the following process: the composition for forming a negative electrode is cast on a separate support, and then the film separated from the support is laminated on a negative electrode current collector.
In the lithium secondary battery, a separator separates a negative electrode and a positive electrode and provides a moving path of lithium ions, wherein any separator may be used as the above-mentioned separator without particular limitation as long as it is generally used in the lithium secondary battery, and in particular, a separator having a high moisture retention capacity for an electrolytic solution and a low resistance to movement of electrolyte ions may be used. Specifically, a porous polymer film such as a porous polymer film prepared from a polyolefin-based polymer (e.g., an ethylene homopolymer, a propylene homopolymer, an ethylene/butene copolymer, an ethylene/hexene copolymer, and an ethylene/methacrylate copolymer), or a laminate structure having two or more layers thereof may be used. Also, a typical porous nonwoven fabric, such as a nonwoven fabric formed of high-melting glass fibers or polyethylene terephthalate fibers, may be used. In addition, a coated separator including a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and a separator having a single-layer or multi-layer structure may be selectively used.
Also, the electrolyte used in the present invention may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, or a melt-type inorganic electrolyte, which may be used to manufacture a lithium secondary battery, but the present invention is not limited thereto.
Specifically, the electrolyte may include an organic solvent and a lithium salt.
Any organic solvent may be used as the above-mentioned organic solvent without particular limitation so long as it can serve as a medium through which ions participating in the electrochemical reaction of the battery can move. Specifically, as the organic solvent, there can be used: ester solvents such as methyl acetate, ethyl acetate, γ -butyrolactone and ∈ -caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; or carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), Ethyl Methyl Carbonate (EMC), Ethylene Carbonate (EC), and Propylene Carbonate (PC); alcohol solvents such as ethanol and isopropanol; nitriles such as R-CN (where R is a linear, branched or cyclic C2-C20 hydrocarbyl group and may include a double bond aromatic ring or ether linkage); amides, such as dimethylformamide; dioxolanes, such as 1, 3-dioxolane; or sulfolane. Among these solvents, a carbonate-based solvent may be preferably used, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ion conductivity and high dielectric constant, which can improve charge/discharge performance of a battery, and a linear carbonate-based compound (e.g., ethylene carbonate, dimethyl carbonate, or diethyl carbonate) having low viscosity may be more preferably used. In this case, when the cyclic carbonate and the linear carbonate are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte solution may be excellent.
The lithium salt may be used without particular limitation so long as it isThe compound may be a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, LiPF can be used as the lithium salt6、LiClO4、LiAsF6、LiBF4、LiSbF6、LiAlO4、LiAlCl4、LiCF3SO3、LiC4F9SO3、LiN(C2F5SO3)2、LiN(C2F5SO2)2、LiN(CF3SO2)2LiCl, LiI or LiB (C)2O4)2. The lithium salt may be used in a concentration range of 0.1M to 2.0M. In the case where the concentration of the lithium salt is included in the above range, since the electrolyte may have appropriate conductivity and viscosity, excellent electrolyte performance may be obtained and lithium ions may be efficiently moved.
In order to improve the life characteristics of the battery, suppress a decrease in the capacity of the battery, and improve the discharge capacity of the battery, at least one additive such as a halogenated alkylene carbonate compound (e.g., difluoroethylene carbonate), pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, N-glyme, hexaphosphoric triamide, a nitrobenzene derivative, sulfur, a quinoneimine dye, N-substituted oxazolidinone, N-substituted imidazolidine, ethylene glycol dialkyl ether, an ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride may be added to the electrolyte in addition to the electrolyte component. In this case, the content of the additive may be 0.1 to 5% by weight, based on the total weight of the electrolyte.
As described above, since the lithium secondary battery including the cathode active material of the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, the lithium secondary battery is suitable for portable devices such as mobile phones, notebook computers, and digital cameras, and electric vehicles such as Hybrid Electric Vehicles (HEVs).
Therefore, according to another embodiment of the present invention, there are provided a battery module including a lithium secondary battery as a unit cell and a battery pack including the same.
The battery module or the battery pack can be used as a power source of at least one of the following medium-large devices: an electric tool; electric vehicles, including Electric Vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or an electrical power storage system.
The shape of the lithium secondary battery of the present invention is not particularly limited, but a cylindrical shape, a prismatic shape, a pouch shape, or a coin shape using a can may be used.
The lithium secondary battery of the present invention may be used not only in a battery cell used as a power source for a small-sized device, but also as a unit cell in a middle or large-sized battery module including a plurality of battery cells.
Hereinafter, embodiments of the present invention will be described in detail in such a manner that those skilled in the art to which the present invention pertains can easily carry out the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.
Example 1
100 parts by weight of an average particle diameter (D)50) Agglomerated LiFePO of 1.2 μm4The positive electrode active material, 1 part by weight of HNBR dispersant (AN: 37 wt%, HBD ratio: 21%), and 65.7 parts by weight of N-methylpyrrolidone solvent were mixed, and a wetting process was performed at 3,000rpm for 60 minutes using a homomixer. Thereafter, a circulation process was performed at 2,000rpm for 90 minutes using a bead mill (bead size: 1mm) to prepare a positive electrode active material pre-dispersion. In this case, LiFePO dispersed in the positive electrode active material pre-dispersion4Average particle diameter (D) of positive electrode active material50) And 0.75 μm.
Reacting LiNi0.6Mn0.2Co0.2O2Positive electrode active material to LiFePO4Added to the positive electrode active material pre-dispersion at a weight ratio of 9:1, and a slurry for a positive electrode was prepared by mixing the positive electrode active material (NMC + LFP), PVdF as a binder, and carbon black as a conductive agent in an N-methylpyrrolidone solvent at a weight ratio of 96:1:3 and dispersed at 3,000rpm for 80 minutes using a homomixer. In this case, a positive electrode was preparedThe solids content of the slurry used was about 60.0%.
Example 2
A positive electrode active material pre-dispersion was prepared in the same manner as in example 1, except that, during the preparation of the positive electrode active material pre-dispersion, the wetting process was performed at 3,000rpm for 60 minutes using a homomixer, and the circulation process was performed at 2,000rpm for 30 minutes using a bead mill (bead size: 1 mm). In this case, LiFePO dispersed in the positive active material pre-dispersion4Average particle diameter (D) of positive electrode active material50) And 0.92 μm.
Example 3
A positive electrode active material pre-dispersion was prepared in the same manner as in example 1, except that, during the preparation of the positive electrode active material pre-dispersion, a wetting process was performed at 3,000rpm for 60 minutes using a homomixer and bead milling was not performed. In this case, LiFePO dispersed in the positive electrode active material pre-dispersion4Average particle diameter (D) of positive electrode active material50) It was 1.17 μm.
Comparative example 1
Average particle diameter (D) of the positive electrode active material50) LiFePO of 1.2 μm4Carbon black as a conductive agent and PVDF as a binder were mixed in an N-methylpyrrolidone solvent in a weight ratio of 85:10:5, a wetting process was performed at 3,000rpm for 60 minutes using a homomixer, and subsequently, a circulation process was performed at 2,000rpm for 90 minutes using a bead mill (bead size: 1mm) to prepare a slurry for a positive electrode.
For comparative example 1 in which a pre-dispersion of the positive electrode active material was not prepared and the positive electrode active material, the conductive agent, and the binder were added at once to prepare the positive electrode slurry, coarse particles having a diameter of about 30 μm were generated because the dispersion of the positive electrode active material was not sufficiently performed. When coarse particles are generated as described above, filter clogging or surface defects (in which particles are generated on the coated surface) may occur during the coating of the positive electrode slurry.
Comparative example 2
A slurry for a positive electrode was prepared in the same manner as in example 1, except that an HNBR dispersant was not added during the preparation of the positive electrode active material pre-dispersion.
[ Experimental example 1: shear viscosity measurement
The shear viscosity of the slurry for a positive electrode prepared in examples 1 to 3 and comparative examples 1 and 2 was measured using a TA instrument rheometer (DHR 2). The shear viscosity was measured in the following manner: using a concentric cylinder attachment to a DHR2 rheometer, 10ml of the slurry was introduced and the viscosity was measured at 25 ℃. The results are shown in FIG. 1.
Referring to fig. 1, for examples 1 to 3 in which lithium iron phosphate-based positive electrode active material was pre-dispersed with HNBR dispersant to prepare a positive electrode active material pre-dispersion, and then a binder and a conductive agent were added to prepare a slurry for a positive electrode, the viscosity was significantly lower than that of comparative example 1 as a whole. This indicates that the dispersibility of the positive electrode active material is significantly improved. For comparative example 2, since the active material particles were dispersed by using a pre-dispersion process without a dispersant, the dispersed particles were re-agglomerated. Therefore, no dispersibility improving effect was observed, and it was confirmed that the viscosity thereof was increased more than that of comparative example 1 without pre-dispersion. Average particle diameter (D) for lithium iron phosphate-based positive electrode active material dispersed so that the positive electrode active material is prepared during pre-dispersion of the positive electrode active material50) Examples 1 and 2, which were less than 1 μm, were further improved in dispersibility, and therefore, it was confirmed that the viscosity thereof was further lowered.
[ Experimental example 2: evaluation of flowability
Viscoelasticity of the slurry for a positive electrode prepared in examples 1 to 3 and comparative examples 1 and 2 was measured using a TA instrument rheometer (DHR 2). Viscoelasticity is measured in the following manner: using a concentric cylinder attachment of a DHR2 rheometer, 10ml of slurry was introduced, and then viscoelasticity was measured at 25 ℃, and in this case viscoelasticity was a response (stress) obtained by applying sine wave vibration (strain) to a fluid, wherein: as the phase angle increases, the viscosity of the fluid increases and the fluidity improves. The measurement results are shown in fig. 2.
Referring to fig. 2, for the pre-dispersion of the lithium iron phosphate-based positive electrode active material with the HNBR dispersant to prepareExamples 1 to 3, in which a pre-dispersion of a positive electrode active material was prepared and then a binder and a conductive agent were added to prepare a slurry for a positive electrode, have viscoelasticity greater than that of comparative example 1, and thus, it can be understood that fluidity was significantly improved. With comparative example 2, since the active material particles were dispersed by using a pre-dispersion process without a dispersant, the dispersed particles did not maintain slurry phase stability and re-aggregated, and thus, it could be confirmed that the fluidity thereof was further reduced. Average particle diameter (D) of lithium iron phosphate-based positive electrode active material for dispersion during preparation of positive electrode active material pre-dispersion50) In examples 1 and 2 having a particle size of less than 1 μm, it was confirmed that the fluidity was further improved. This seems to be an effect of reducing the structure formation between particles in the positive electrode slurry due to the improvement of dispersibility.
[ Experimental example 3: evaluation of adhesion of Positive electrode
The slurry for positive electrodes prepared in examples 1 to 3 and comparative examples 1 and 2 was respectively coated on aluminum current collectors, dried at 130 ℃, and then pressed to prepare each positive electrode.
The adhesion of the positive electrode prepared by using each of the slurries for a positive electrode prepared in examples 1 to 3 and comparative examples 1 and 2 was measured using a TXA Universal Tester (UTM). In this measurement method, a positive electrode punched out into a region of 10mm × 150mm is attached to a slide glass to which a double-sided tape is attached. Thereafter, in order to obtain a uniform adhesion surface, a sample was prepared by pressing the positive electrode using a roller having a load of 2kg, the prepared sample was placed in a measuring unit of an adhesion force measuring instrument and then peeled off at an angle of 180 degrees, and the measurement result thereof was shown in fig. 3.
Referring to fig. 3, for examples 1 to 3 in which lithium iron phosphate-based positive electrode active material was pre-dispersed with HNBR dispersant to prepare a positive electrode active material pre-dispersion, and then a binder and a conductive agent were added to prepare a slurry for a positive electrode, it can be understood that the electrode adhesion was significantly increased as compared to comparative examples 1 and 2. It is considered that, with comparative examples 1 and 2, since the binder present in the aggregated positive electrode active material particles does not contribute to the adhesion force, the adhesion force thereof is lowered.
Average particle diameter (D) for lithium iron phosphate-based positive electrode active material dispersed so that the positive electrode active material is prepared during pre-dispersion of the positive electrode active material50) In examples 1 and 2 having a size of less than 1 μm, since the electrode adhesion was further improved, it was understood that the more the dispersibility of the positive electrode active material was improved, the more the electrode adhesion was improved. Therefore, as in examples 1 and 2, there is an advantage in that the ratio of the binder in the electrode composition can be reduced as the adhesion of the electrode is improved.

Claims (14)

1. A method of preparing a slurry composition for a positive electrode of a secondary battery, the method comprising:
preparing a positive electrode active material pre-dispersion by mixing a lithium iron phosphate-based positive electrode active material, a dispersant and a solvent such that the average particle diameter D of the lithium iron phosphate-based positive electrode active material contained in the positive electrode active material pre-dispersion50Less than 1 μm; and
further mixing a conductive agent, a binder and an additional solvent with the positive active material pre-dispersion to prepare a slurry composition for a secondary battery positive electrode;
wherein the dispersant comprises Hydrogenated Nitrile Butadiene Rubber (HNBR).
2. The method according to claim 1, wherein the mixing amount of the dispersant is 0.8 to 1.5 parts by weight based on 100 parts by weight of the lithium iron phosphate-based positive electrode active material.
3. The method according to claim 1, wherein in the preparation of the positive electrode active material pre-dispersion, the lithium iron phosphate-based positive electrode active material, a dispersant and a solvent are added and dispersed by stirring or milling.
4. The method according to claim 1, wherein the preparing of the positive electrode active material pre-dispersion is performed such that the viscosity of the positive electrode active material pre-dispersion is 2,000cps to 20,000cps at 25 ℃.
5. The method of claim 1, wherein the lithium iron phosphate-based positive electrode active material is represented by formula 1:
[ formula 1]
Li1+a1Fe1-x1M1 x1PO4-b1Ab1
Wherein, in formula 1, M1Is at least one selected from the group consisting of manganese (Mn), nickel (Ni), cobalt (Co), copper (Cu), scandium (Sc), titanium (Ti), chromium (Cr), vanadium (V) and zinc (Zn), A is at least one selected from the group consisting of sulfur (S), selenium (Se), fluorine (F), chlorine (Cl) and iodine (I), -0.5<a1<0.5，0≤x1<0.5 and 0. ltoreq. b 1. ltoreq.0.1.
6. The method according to claim 1, wherein the binder comprises at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubber, or a copolymer thereof.
7. The method according to claim 1, wherein the conductive agent comprises at least one selected from the group consisting of carbon black, graphite, carbon fiber, carbon nanotube, metal powder, metal fiber, conductive metal oxide, conductive whisker, and conductive polymer.
8. The method according to claim 1, wherein the conductive agent comprises at least one selected from the group consisting of acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black.
9. The method of claim 1, wherein the preparing of the slurry for a positive electrode comprises further mixing a positive electrode active material of the lithium composite transition metal oxide represented by formula 2 with the positive electrode active material pre-dispersion:
[ formula 2]
Lia2Ni1-x2-y2Cox2M3 y2M4 z2O2
Wherein, in formula 2, a2 is more than or equal to 1.0 and less than or equal to 1.5, 0<x2≤0.2，0<y2≤0.2，0≤z2≤0.1，M3Is at least one selected from the group consisting of manganese (Mn) and aluminum (Al), and M4Is at least one selected from the group consisting of barium (Ba), calcium (Ca), zirconium (Zr), titanium (Ti), magnesium (Mg), tantalum (Ta), niobium (Nb), and molybdenum (Mo).
10. The method according to claim 9, wherein the lithium iron phosphate-based positive electrode active material and the positive electrode active material of the lithium composite transition metal oxide represented by formula 2 are mixed in a weight ratio of 1:99 to 40: 60.
11. A positive electrode active material pre-dispersion composition comprising a lithium iron phosphate-based positive electrode active material, a dispersant and a solvent,
wherein the lithium iron phosphate-based positive electrode active material has an average particle diameter D50Primary particles of less than 1 μm, and
the viscosity of the positive active material pre-dispersion composition is 2,000cps to 20,000cps at 25 ℃.
12. A slurry composition for a secondary battery positive electrode, comprising the positive electrode active material pre-dispersion composition of claim 11, further comprising a conductive agent and a binder.
13. A secondary battery positive electrode produced using the slurry composition for a secondary battery positive electrode according to claim 12.
14. A lithium secondary battery comprising the positive electrode for a secondary battery according to claim 13.
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WO2020235760A1 (en) * 2019-05-17 2020-11-26 한국기계연구원 Additive for secondary battery, electrode slurry comprising same for secondary battery, and secondary battery
CN112768692B (en) * 2021-01-08 2022-03-22 陕西煤业化工技术研究院有限责任公司 Lithium ion battery anode slurry and preparation method and application thereof
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EP4280309A4 (en) * 2022-03-31 2024-04-10 Contemporary Amperex Technology Co Ltd Positive electrode sheet, secondary battery, and electrical apparatus
CN116799151A (en) * 2022-03-31 2023-09-22 宁德时代新能源科技股份有限公司 Positive electrode sheet, secondary battery and electricity utilization device
CN117678092A (en) * 2022-03-31 2024-03-08 宁德时代新能源科技股份有限公司 Positive electrode sheet, secondary battery and electricity utilization device
CN117223130A (en) * 2022-04-01 2023-12-12 宁德时代新能源科技股份有限公司 Positive electrode active material composition, positive electrode sheet, secondary battery, battery module, battery pack, and electric device
CN117716541A (en) * 2022-04-01 2024-03-15 宁德时代新能源科技股份有限公司 Dispersant composition, positive electrode sheet, secondary battery, battery module, battery pack, and electric device
EP4318670A1 (en) * 2022-04-01 2024-02-07 Contemporary Amperex Technology Co., Limited Positive electrode active material composition, positive electrode sheet, secondary battery, battery module, battery pack, and electrical device
EP4280311A1 (en) * 2022-04-01 2023-11-22 Contemporary Amperex Technology Co., Limited Positive-electrode active material composition, positive electrode plate, secondary battery, battery module, battery pack and electric apparatus

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2607059A1 (en) * 2005-05-06 2006-11-16 Phostech Lithium Inc. Electrode material including a lithium/transition metal complex oxide
CN102106023A (en) * 2008-07-30 2011-06-22 东洋油墨制造株式会社 Positive mix paste for lithium secondary battery
EP2522625A1 (en) * 2011-05-13 2012-11-14 Shin-Etsu Chemical Co., Ltd. Preparation of particulate positive electrode material for lithium ion cells
JP2013084397A (en) * 2011-10-06 2013-05-09 Toyota Motor Corp Lithium secondary battery manufacturing method
WO2015098116A1 (en) * 2013-12-27 2015-07-02 日本ゼオン株式会社 Conductive material paste for secondary battery electrode, method for producing slurry for secondary battery cathode, method for producing secondary battery cathode, and secondary battery
CN104798230A (en) * 2012-11-20 2015-07-22 住友金属矿山株式会社 Coated nickel hydroxide powder for alkali secondary battery positive electrode active material and method of producing same
WO2016200223A1 (en) * 2015-06-12 2016-12-15 주식회사 엘지화학 Positive electrode mixture and secondary battery including same
CN106299291A (en) * 2016-09-09 2017-01-04 深圳市沃特玛电池有限公司 A kind of ultralow temperature lithium iron phosphate dynamic battery and preparation method thereof
JP2017054649A (en) * 2015-09-08 2017-03-16 株式会社豊田自動織機 Method of producing composition containing plural positive electrode active materials, conductive assistant, binder and solvent

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4798951B2 (en) 2004-03-04 2011-10-19 三洋電機株式会社 Non-aqueous electrolyte battery positive electrode and battery using this positive electrode
WO2010026627A1 (en) * 2008-09-03 2010-03-11 住友大阪セメント株式会社 Method for producing electrode material, electrode material, electrode, and battery
US20120015245A1 (en) * 2010-07-15 2012-01-19 Semiconductor Energy Laboratory Co., Ltd. Manufacturing method of electrode of power storage device, electrode of power storage device, and power storage device
KR20140032229A (en) * 2012-09-06 2014-03-14 삼성에스디아이 주식회사 Positive active material composition for rechargeable lithium battery, and positive electrode and rechargeable lithium battery including the same
JP5652633B1 (en) * 2013-05-24 2015-01-14 Jsr株式会社 Lithium ion secondary battery composition, lithium ion secondary battery slurry, lithium ion secondary battery electrode, lithium ion secondary battery separator, and lithium ion secondary battery
KR20150016852A (en) * 2013-08-05 2015-02-13 제일모직주식회사 Carbon nanotube dispersed solution and method for preparing the same
KR102234295B1 (en) * 2014-01-10 2021-03-31 삼성에스디아이 주식회사 Composite binder composition for secondary battery, cathode and lithium battery containing the binder
CN105932282A (en) * 2016-06-08 2016-09-07 湖南锂顺能源科技有限公司 Lithium ion battery and preparation method thereof

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2607059A1 (en) * 2005-05-06 2006-11-16 Phostech Lithium Inc. Electrode material including a lithium/transition metal complex oxide
CN102106023A (en) * 2008-07-30 2011-06-22 东洋油墨制造株式会社 Positive mix paste for lithium secondary battery
EP2522625A1 (en) * 2011-05-13 2012-11-14 Shin-Etsu Chemical Co., Ltd. Preparation of particulate positive electrode material for lithium ion cells
JP2013084397A (en) * 2011-10-06 2013-05-09 Toyota Motor Corp Lithium secondary battery manufacturing method
CN104798230A (en) * 2012-11-20 2015-07-22 住友金属矿山株式会社 Coated nickel hydroxide powder for alkali secondary battery positive electrode active material and method of producing same
WO2015098116A1 (en) * 2013-12-27 2015-07-02 日本ゼオン株式会社 Conductive material paste for secondary battery electrode, method for producing slurry for secondary battery cathode, method for producing secondary battery cathode, and secondary battery
WO2016200223A1 (en) * 2015-06-12 2016-12-15 주식회사 엘지화학 Positive electrode mixture and secondary battery including same
JP2017054649A (en) * 2015-09-08 2017-03-16 株式会社豊田自動織機 Method of producing composition containing plural positive electrode active materials, conductive assistant, binder and solvent
CN106299291A (en) * 2016-09-09 2017-01-04 深圳市沃特玛电池有限公司 A kind of ultralow temperature lithium iron phosphate dynamic battery and preparation method thereof

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