WO2018143576A1 - Batterie secondaire au lithium - Google Patents

Batterie secondaire au lithium Download PDF

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Publication number
WO2018143576A1
WO2018143576A1 PCT/KR2018/000482 KR2018000482W WO2018143576A1 WO 2018143576 A1 WO2018143576 A1 WO 2018143576A1 KR 2018000482 W KR2018000482 W KR 2018000482W WO 2018143576 A1 WO2018143576 A1 WO 2018143576A1
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active material
positive electrode
secondary battery
lithium secondary
lithium
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PCT/KR2018/000482
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English (en)
Korean (ko)
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박상인
이준규
이진헌
임대섭
권혜진
심규윤
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삼성에스디아이 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/044—Activating, forming or electrochemical attack of the supporting material
    • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
    • H01M4/0447—Forming after manufacture of the electrode, e.g. first charge, cycling of complete cells or cells stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to a lithium secondary battery.
  • Lithium secondary batteries which are in the spotlight as power sources of recent portable small electronic devices, use organic electrolytes and exhibit a discharge voltage that is two times higher than that of a battery using an alkaline aqueous solution. As a result, the lithium secondary battery has a high energy density.
  • lithium and a transition metal having a structure capable of intercalating lithium ions such as LiCoO 2 , LiMn 2 O 4 , LiNi 1 - x Co x O 2 (0 ⁇ x ⁇ 1), etc. Oxides are mainly used.
  • Examples of the negative electrode active material include various types of carbon-based material negative electrode active materials including artificial, natural graphite, and hard carbon capable of inserting / desorbing lithium, or negative electrode active materials of oxides such as tin oxide and lithium vanadium oxide.
  • the electrode density of the electrode plate is too high, it is difficult to impregnate the electrolyte, and the channel should be well formed from the top of the electrode plate (bottom) to the bottom (current collector side), so that the electrolyte penetrates well into the inside of the electrode plate, thereby removing and inserting lithium ions.
  • the electrode density is too high, voids are lost between the active materials to block the flow path, and thus the capacity of the lithium ion battery may not be properly expressed, or lithium may be deposited on the negative electrode, thereby deteriorating the lifespan.
  • One embodiment of the present invention is to provide a lithium secondary battery having excellent electrolyte solution impregnation property, high capacity and energy density in a high electrode.
  • a hole having an average particle diameter (D50) of 1200 nm to 50 ⁇ m exists on a surface thereof, and includes a positive electrode including a positive electrode active material; A negative electrode including a negative electrode active material; And it provides a lithium secondary battery comprising an electrolyte.
  • D50 average particle diameter
  • the average particle diameter (D50) of the hole may be 5 ⁇ m to 50 ⁇ m.
  • the aspect ratio of the hole may be 0.5 to 2.
  • the ratio of the average particle diameter (D50) of the positive electrode active material to the average particle diameter (D50) of the hole may be less than 1, and the ratio of the average particle diameter (D50) of the positive electrode active material to the average particle diameter (D50) of the hole is 0.2 to 0.6. Can be.
  • the mixture density of the positive electrode may be 2 g / cc to 4.3 g / cc.
  • Carbon coating layer may be formed on the surface of the hole.
  • the lithium secondary battery may be prepared by performing a chemical conversion process on a battery prepared using a cathode, an anode, and an electrolyte prepared using a cathode active material composition including a cathode active material and a pore-forming agent.
  • the lithium secondary battery according to one embodiment of the present invention may exhibit excellent energy density and capacity due to excellent electrolyte impregnation of the electrode.
  • FIG. 1 is a view schematically showing the structure of a lithium secondary battery according to one embodiment of the present invention.
  • Figure 2 is a SEM image of the surface of the positive electrode obtained by decomposing in a state before chemical conversion after rolling the lithium secondary battery prepared according to Example 1.
  • Figure 3 is a SEM image of the surface of the positive electrode obtained by decomposing the lithium secondary battery prepared according to Example 1 in the state after ignition.
  • Figure 4 is a SEM image of the surface of the positive electrode obtained by decomposing the lithium secondary battery prepared according to Example 1 in the state after ignition.
  • Example 5 is a graph showing the weight of the lithium secondary battery of Example 1 and Comparative Example 1 over time.
  • FIG. 6 is a graph showing capacity retention rates of the lithium secondary batteries of Example 1 and Comparative Example 1.
  • Lithium secondary battery has a hole having an average particle diameter (D50) of 1200nm to 50 ⁇ m on the surface, the positive electrode comprising a positive electrode active material; A negative electrode including a negative electrode active material; And electrolytes.
  • D50 average particle diameter
  • the average particle diameter (D50) refers to the diameter of the particles having a cumulative volume of 50% by volume in the particle size distribution.
  • the average particle diameter (D50) of the hole formed on the surface of the anode may be 1200nm to 50 ⁇ m, in another embodiment may be 5 ⁇ m to 50 ⁇ m.
  • the average particle diameter (D50) of the hole is included in the above range, the electrolyte impregnation property is improved in the electrode, and the flow path is formed in the electrode, so that the electrolyte solution can be well impregnated throughout the electrode, so that the lithium ion can be easily inserted and removed, It can also be increased.
  • the hole When the hole is formed on the surface may be a hemispherical shape, but is not limited thereto, and may be any shape. In addition, even when a hole is formed in an electrode, the form does not need to be largely limited.
  • the aspect ratio of the hole may be 0.5 to 2. When the aspect ratio of the hole is out of the range, the electrolyte may not be well impregnated.
  • the ratio of the average particle diameter (D50) of the positive electrode active material to the average particle diameter (D50) of the hole may be less than 1.
  • the ratio of the average particle diameter (D50) of the positive electrode active material to the average particle diameter (D50) of the hole may be 0.2 to 0.6.
  • the mixture density of the positive electrode may be 2 g / cc to 4.3 g / cc.
  • the higher the mixture density of the positive electrode the denser the active material layer, so that the electrolyte solution impregnation may be lowered.
  • the cathode according to the embodiment of the present invention may improve the electrolyte impregnation property because holes are formed. The effect can be increased. That is, since the effect of improving the electrolyte impregnation property according to the hole formation can be obtained more effectively as the mixture density is higher, better electrolyte impregnation can be obtained by forming holes in the anode having the mixture density included in the above range.
  • the surface of the hole may further include a carbon coating layer.
  • the conductivity of the positive electrode active material layer (mixture layer) is increased to control the amount of the conductive material.
  • Carbon of the carbon coating layer may be a hydrocarbon such as graphene, carbon black, carbon nanotube, methane, or a combination thereof.
  • the thickness of the carbon coating layer may be 10nm to 1 ⁇ m.
  • the content of the carbon coating layer may be 0.05 wt% to 0.5 wt% with respect to 100 wt% of the cathode active material.
  • a lithium secondary battery having such a configuration may be manufactured by performing a chemical conversion process on a battery manufactured using a cathode, an anode, and an electrolyte manufactured using a cathode active material composition including a cathode active material and a wax-coated lithium metal.
  • a lithium secondary battery manufacturing process according to an embodiment of the present invention will be described in detail below.
  • a cathode of a lithium secondary battery prepares a cathode active material composition including a cathode active material and a wax-coated lithium metal.
  • the content of the wax-coated lithium metal may be 0.1 wt% to 1 wt% with respect to 100 wt% of the cathode active material. When the content of the wax-coated lithium metal is included in the above range, it may exhibit more appropriate cycle life characteristics of the battery.
  • the content ratio of the wax and the lithium metal may be 0.5: 1 to 3: 1 weight ratio.
  • the content ratio of the wax and the lithium metal is included in the above range, battery characteristics can be improved more effectively, which is appropriate.
  • the average particle diameter (D50) of the lithium metal may be 1200 nm to 50 ⁇ m.
  • a hole having an appropriate size may be formed.
  • the wax coating that is, the thickness of the wax coating layer may be 1 ⁇ m to 10 ⁇ m. When the thickness of the wax coating layer falls within this range, lithium metal can be easily handled in air.
  • the wax coating process may be used, and therefore, there is no need to limit the wax coating process.
  • lithium metal when lithium metal is used for the positive electrode, since the potential energy of the positive electrode and the potential energy of the lithium metal are different, a short circuit may occur.
  • the wax covers the lithium metal to prevent short circuits.
  • the wax-coated lithium metal may be further coated with carbon. That is, a wax coating layer is present on the lithium metal surface, and a carbon coating layer may be present on the wax coating layer surface.
  • Carbon of the carbon coating layer may be a hydrocarbon such as graphene, carbon black, carbon nanotube, methane, or a combination thereof.
  • the thickness of the carbon coating layer may be 10nm to 1 ⁇ m.
  • the content of the carbon coating layer may be 0.05 wt% to 0.5 wt% with respect to 100 wt% of the lithium metal. When the content of the carbon coating layer is included in the above range, it is possible to further improve the use efficiency, it is appropriate.
  • the wax may be a microcrystalline wax, an olefin compound, or an oil type liquid wax. Or combinations thereof.
  • the microstalin wax is also referred to as a micro wax, and refers to a wax that has undergone dewaxing or deoiling by solvent extraction from high viscosity lubricating distillates (Lube distilate oil) produced during crude oil refining. It is a wax which contains a branched saturated hydrocarbon as a main component.
  • the positive electrode active material Compounds capable of reversible intercalation and deintercalation of lithium (lithiated intercalation compounds) can be used. Specifically, at least one of a complex oxide of metal and lithium selected from cobalt, manganese, nickel, and a combination thereof can be used. More specific examples may be used a compound represented by any one of the following formula.
  • Li a A 1 - b X b D 2 (0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5); Li a A 1 - b X b O 2 - c D c (0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a E 1-b X b O 2-c D c (0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a E 2 - b X b O 4 - c D c (0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.05); Li a Ni 1 -b- c Co b X c D ⁇ (0.90 ⁇ a ⁇ 1.8, 0 ⁇ b ⁇ 0.5, 0 ⁇ c ⁇ 0.5, 0 ⁇ ⁇ 2); Li a Ni 1 -b- c Co b c D
  • A is selected from the group consisting of Ni, Co, Mn, and combinations thereof;
  • X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements and combinations thereof;
  • D is selected from the group consisting of O, F, S, P, and combinations thereof;
  • E is selected from Co, Mn, and combinations thereof;
  • T is selected from the group consisting of F, S, P, and combinations thereof;
  • G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof;
  • Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof;
  • Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof;
  • J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.
  • the coating layer may include at least one coating element compound selected from the group consisting of oxides of the coating elements, hydroxides of the coating elements, oxyhydroxides of the coating elements, oxycarbonates of the coating elements and hydroxycarbonates of the coating elements. Can be.
  • the compounds constituting these coating layers may be amorphous or crystalline.
  • As a coating element included in the coating layer Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof may be used.
  • the coating layer forming process may use any coating method as long as it can be coated with the above compounds by a method that does not adversely affect the physical properties of the positive electrode active material (for example, spray coating or dipping method). Detailed descriptions thereof will be omitted since they can be understood by those skilled in the art.
  • the positive electrode active material composition may further include a binder and a conductive material.
  • the binder is a material that adheres the positive electrode active material particles to each other well, and also attaches the positive electrode active material to the current collector well.
  • Representative examples of the binder include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinylchloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpi Lollidon, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene butadiene rubber, epoxy resin, nylon, and the like may be used, but is not limited thereto. .
  • the conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electron conductive material without causing chemical change in the battery.
  • the conductive material include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, and carbon fiber; Metal materials such as metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive polymers such as polyphenylene derivatives; Or a conductive material containing a mixture of these.
  • the positive electrode active material composition may further include a solvent, and the solvent may include N-methylpyrrolidone, but is not limited thereto.
  • the amount of the cathode active material in the cathode active material composition may be 85 wt% to 97.6 wt% with respect to the total weight of the cathode active material composition solids.
  • the content of the lithium metal coated with the wax may be 0.1% by weight to 1% by weight based on the total weight of the positive electrode active material composition solids.
  • the content of the binder may be 1.0 wt% to 5 wt% with respect to the total weight of the cathode active material composition solids.
  • the content of the conductive material may be 1.3 wt% to 10 wt% with respect to the total weight of the cathode active material composition solids.
  • the positive electrode is manufactured by a conventional process of applying, drying, and rolling the positive electrode active material composition to a current collector.
  • Al foil may be used as the current collector, but is not limited thereto.
  • a lithium secondary battery is assembled in a conventional process using the negative electrode and the electrolyte including the positive electrode, the negative electrode active material.
  • the assembled lithium secondary battery is subjected to a chemical conversion process.
  • holes are formed on the surface of the cathode as the lithium metal contained in the anode is dissolved and eluted from the anode.
  • holes may be formed in the anode as a whole.
  • the eluted lithium metal may compensate for the irreversible Li amount of the positive electrode active material that does not participate in the charge / discharge reaction as it participates in the reaction of forming the SEI film during charge and discharge, and thus the lithium secondary battery including the positive electrode has a high capacity. Can be improved.
  • lithium metal is dissolved and removed from the positive electrode.
  • the wax coated on the lithium metal surface may also be removed together, but some may remain in the positive electrode. If the wax remains at the positive electrode, the wax is electrically inert and does not cause side reactions, so even if the wax remains at the positive electrode, it does not adversely affect the battery.
  • wax and carbon may remain in the positive electrode. In this case, a coating layer formed of carbon may exist on the surface of the hole.
  • the chemical conversion process may be performed by a process of charging and discharging once or twice at 0.1C to 0.5C.
  • the negative electrode includes a negative electrode active material layer including a current collector and a negative electrode active material formed on the current collector.
  • the anode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material doped and undoped with lithium, or a transition metal oxide.
  • any carbon-based negative electrode active material generally used in a lithium ion secondary battery may be used, and representative examples thereof include crystalline carbon. , Amorphous carbon or these can be used together.
  • the crystalline carbon include graphite such as amorphous, plate, flake, spherical or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon ( hard carbon), mesophase pitch carbide, calcined coke, and the like.
  • alloy of the lithium metal examples include lithium and Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn. Alloys of the metals selected may be used.
  • the lithium doped and undoped materials include Si, Si-C composites, SiO x (0 ⁇ x ⁇ 2), Si-Q alloy (Q is an alkali metal, alkaline earth metal, group 13 element, group 14 element, An element selected from the group consisting of Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, not Si), Sn, SnO 2 , Sn-R alloys (wherein R is an alkali metal, an alkaline earth metal, Element selected from the group consisting of Group 13 elements, Group 14 elements, Group 15 elements, Group 16 elements, transition metals, rare earth elements, and combinations thereof, and not Sn).
  • SiO 2 can also be mixed and used.
  • the elements Q and R include Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, One selected from the group consisting of S, Se, Te, Po, and a combination thereof can be used.
  • transition metal oxide examples include vanadium oxide, lithium vanadium oxide or lithium titanium oxide.
  • the content of the negative electrode active material in the negative electrode active material layer may be 95% by weight to 99% by weight with respect to the total weight of the negative electrode active material layer.
  • the negative electrode active material layer includes a binder, and optionally may further include a conductive material.
  • the content of the binder in the negative electrode active material layer may be 1% by weight to 5% by weight based on the total weight of the negative electrode active material layer.
  • 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material may be used.
  • the binder adheres the anode active material particles to each other well, and also serves to adhere the anode active material to the current collector well.
  • a water-insoluble binder, a water-soluble binder or a combination thereof can be used as the binder.
  • the water-insoluble binder includes polyvinyl chloride, carboxylated polyvinylchloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride , Polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.
  • the water-soluble binder may be a rubber binder or a polymer resin binder.
  • the rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluorine rubber, and combinations thereof.
  • the polymer resin binder may be ethylene propylene copolymer, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, It may be selected from acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol and combinations thereof.
  • a water-soluble binder When using a water-soluble binder as the negative electrode binder, it may further include a cellulose-based compound that can impart viscosity as a thickener.
  • a cellulose-based compound that can impart viscosity as a thickener.
  • carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, these alkali metal salts, etc. can be used in mixture of 1 or more types. Na, K or Li may be used as the alkali metal.
  • the amount of the thickener used may be 0.1 parts by weight to 3 parts by weight based on 100 parts by weight of the negative electrode active material.
  • the conductive material is used to impart conductivity to the electrode, and any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery.
  • any battery can be used as long as it is an electronic conductive material without causing chemical change in the battery.
  • Carbon-based materials such as black and carbon fibers;
  • Metal materials such as metal powder or metal fibers such as copper, nickel, aluminum and silver; Conductive polymers such as polyphenylene derivatives; Or a conductive material containing a mixture thereof.
  • the current collector may be selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof.
  • the electrolyte includes a non-aqueous organic solvent and a lithium salt.
  • the non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.
  • non-aqueous organic solvent a carbonate-based, ester-based, ether-based, ketone-based, alcohol-based, or aprotic solvent may be used.
  • Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), and ethylene carbonate ( EC), propylene carbonate (PC), butylene carbonate (BC) and the like can be used.
  • the ester solvent may be methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, and caprolactone. And the like can be used.
  • Dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, etc. may be used as the ether solvent.
  • cyclohexanone may be used as the ketone solvent.
  • ethyl alcohol, isopropyl alcohol, etc. may be used as the alcohol solvent, and the aprotic solvent may be R-CN (R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms. Nitriles such as a double bond aromatic ring or ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, sulfolane, and the like can be used. .
  • the organic solvents may be used alone or in combination of one or more, and the mixing ratio in the case of mixing one or more may be appropriately adjusted according to the desired battery performance, which can be widely understood by those skilled in the art. have.
  • the carbonate solvent it is preferable to use a mixture of cyclic carbonate and chain carbonate.
  • the cyclic carbonate and the chain carbonate may be mixed and used in a volume ratio of 1: 1 to 1: 9, so that the performance of the electrolyte may be excellent.
  • the organic solvent may further include an aromatic hydrocarbon organic solvent in the carbonate solvent.
  • the carbonate solvent and the aromatic hydrocarbon organic solvent may be mixed in a volume ratio of 1: 1 to 30: 1.
  • an aromatic hydrocarbon compound of Formula 1 may be used as the aromatic hydrocarbon-based organic solvent.
  • R 1 to R 6 are the same as or different from each other and are selected from the group consisting of hydrogen, halogen, an alkyl group having 1 to 10 carbon atoms, a haloalkyl group, and a combination thereof.
  • aromatic hydrocarbon organic solvent examples include benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3-tri Fluorobenzene, 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1 , 2,4-trichlorobenzene, iodobenzene, 1,2-dioodobenzene, 1,3-dioiobenzene, 1,4-dioiobenzene, 1,2,3-triiodobenzene, 1, 2,4-triiodobenzene, toluene, fluorotoluene, 2,3-difluorotoluene, 2,4-difluorotol, to
  • the electrolyte may further include vinylene carbonate or an ethylene-based carbonate compound represented by Chemical Formula 2 as a life improving additive to improve battery life.
  • R 7 and R 8 are the same as or different from each other, and are selected from the group consisting of hydrogen, a halogen group, a cyano group (CN), a nitro group (NO 2 ), and an alkyl group having 1 to 5 fluorinated carbon atoms. At least one of R 7 and R 8 is selected from the group consisting of a halogen group, a cyano group (CN), a nitro group (NO 2 ) and a fluorinated C1-5 alkyl group, provided that both R 7 and R 8 are all Not hydrogen.
  • ethylene-based carbonate compound examples include difluoro ethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, bromoethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, or fluoroethylene carbonate. Can be mentioned. In the case of further using such life improving additives, the amount thereof can be properly adjusted.
  • the lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions in the battery to enable the operation of a basic lithium secondary battery and to promote the movement of lithium ions between the positive electrode and the negative electrode.
  • Representative examples of such lithium salts are LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiN (SO 2 C 2 F 5 ) 2 , Li (CF 3 SO 2 ) 2 N, LiN (SO 3 C 2 F 5 ) 2 , LiC 4 F 9 SO 3 , LiClO 4 , LiAlO 2 , LiAlCl 4 , LiN (C x F 2x + 1 SO 2 ) (C y F 2y + 1 SO 2 ), where x and y are natural numbers, for example Supporting one or more selected from the group consisting of LiCl, LiI and LiB (C 2 O 4 ) 2 (lithium bis (oxalato) borate (LiBOB)); It is preferable to
  • a separator may exist between the positive electrode and the negative electrode.
  • the separator polyethylene, polypropylene, polyvinylidene fluoride or two or more multilayer films thereof may be used, and polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / poly It goes without saying that a mixed multilayer film such as a propylene three-layer separator can be used.
  • FIG. 1 is an exploded perspective view of a rechargeable lithium battery according to one embodiment of the present invention.
  • a lithium secondary battery according to an embodiment is described as an example of being rectangular, the present invention is not limited thereto, and may be applied to various types of batteries, such as a cylindrical shape and a pouch type.
  • the lithium secondary battery 100 includes an electrode assembly 40 and an electrode assembly 40 interposed between the positive electrode 10 and the negative electrode 20 with a separator 30 interposed therebetween. It may include a case 50 is built.
  • the positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown).
  • LiCoO 2 cathode active material (average particle diameter (D50): 20 ⁇ m) 97.4% by weight, microcrystalline wax (trade name: microcrystalline wax, manufacturer: Southeast Emulsification, city name: Seoul, country of origin: Korea) coated lithium metal (average)
  • a positive electrode active material slurry was prepared by mixing 0.2 wt% of a particle diameter (D50): 50 ⁇ m), 1.1 wt% of polyvinylidene fluoride, and 1.3 wt% of Ketjen Black in an N-methyl pyrrolidone solvent.
  • the mixing ratio of the microcrystalline wax and the lithium metal was 0.7: 0.3 by weight, and the microcrystalline wax coating, that is, the thickness of the coating layer was 2 ⁇ m.
  • the positive electrode active material slurry was applied to an Al current collector, dried, and rolled to prepare a positive electrode for a lithium secondary battery having a mixture density of 4.0 g / cc.
  • a mixed solvent (1: 1 volume ratio) of ethylene carbonate and dimethyl carbonate in which 1.0 M LiPF 6 was dissolved was prepared.
  • Polyethylene film was used as the separator.
  • a lithium secondary battery was manufactured in a conventional process using the positive electrode, the separator, the negative electrode, and the electrolyte solution.
  • the chemical conversion process of charging and discharging the manufactured lithium secondary battery at 0.1C once was performed.
  • microcrystalline wax-coated lithium metal instead of the microcrystalline wax-coated lithium metal, it was carried out in the same manner as in Example 1 except that the microcrystalline wax was coated on the lithium metal surface and coated with graphene on the microcrystalline wax. .
  • a positive electrode active material slurry was prepared by mixing 97.6 wt% of a LiCoO 2 positive electrode active material (average particle diameter (D 50): 20 ⁇ m), 1.1 wt% of polyvinylidene fluoride, and 1.3 wt% of Ketjen Black in an N-methyl pyrrolidone solvent.
  • the positive electrode active material slurry was applied to an Al current collector, dried, and rolled to prepare a positive electrode for a lithium secondary battery having a mixture density of 4.0 g / cc.
  • a lithium secondary battery was manufactured in a conventional process using the positive electrode and the negative electrode, electrolyte solution, and separator prepared in Example 1, and the chemical conversion process was performed in the same manner as in Example 1.
  • Example 1 the lithium secondary battery before carrying out the rolling step and the chemical conversion step was decomposed to show a 500-time magnification SEM photograph of the positive electrode surface. Further, the lithium secondary battery subjected to the chemical conversion process in Example 1 was decomposed, and 50-, 100-, and 1000-magnification SEM photographs of the positive electrode surface are shown in FIGS. 3A, 3B, and 3C, respectively. It was.
  • a black point represents a wax
  • FIG. 3 (C) is an enlarged view of the black point shown by the circle of FIG. 3 (A), as shown in (C)
  • Example 1 it can be seen that a hole having a particle size of about 38.7 ⁇ m is formed on the surface of the anode.
  • the lithium secondary battery of Example 1 using the microcrystalline wax-coated lithium metal for the positive electrode since the lithium metal is eluted and removed from the positive electrode after performing the chemical conversion process, it can be seen that holes are formed on the positive electrode surface. have.
  • Example 1 the lithium secondary battery subjected to the chemical conversion process in Example 1 was decomposed, and 1000 magnification SEM photographs were taken at various points on the surface of the positive electrode. And (F), respectively. As shown in FIG. 4, it can be seen that holes having a size of about 22 ⁇ m to about 41.2 ⁇ m are formed on the surface of the anode subjected to the chemical conversion process.
  • the aspect ratio of the hole formed on the surface of the anode may be about 0.8.
  • the weight of the positive electrode of Example 1 was greater than that of Comparative Example 1 at the same time, and it can be seen from the result that the electrolyte solution impregnation rate of Example 1 was faster than that of Comparative Example 1.
  • the lithium secondary battery subjected to the chemical conversion process according to Example 1 and Comparative Example 1 was subjected to 180 charge / discharge cycles at 0.5C. Every 50 charge / discharge cycles, C-rate was changed to 0.2C, and charging / discharging was performed once.
  • the lithium secondary battery according to Example 1 may proceed with 180 charge / discharge cycles, but in Comparative Example 1, it can be seen that the charge / discharge cycle may be performed up to about 130 times. In addition, it can be seen that the capacity retention rate of Example 1 was superior to that of Comparative Example 1. From this result, it turns out that the charge / discharge cycle life characteristic of Example 1 is superior to the comparative example 1.

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Abstract

La présente invention concerne une batterie secondaire au lithium comprenant : une électrode positive comprenant des trous ayant un diamètre moyen (D50) de 5 à 50 µm à sa surface et comprenant un matériau actif d'électrode positive ; une électrode négative comprenant un matériau actif d'électrode négative ; et un électrolyte.
PCT/KR2018/000482 2017-02-02 2018-01-10 Batterie secondaire au lithium WO2018143576A1 (fr)

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KR20140132292A (ko) * 2013-05-07 2014-11-17 주식회사 엘지화학 이차전지용 전극, 그의 제조방법, 그를 포함하는 이차전지 및 케이블형 이차전지
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JP2001222995A (ja) * 2000-02-08 2001-08-17 Shin Kobe Electric Mach Co Ltd リチウムイオン二次電池
JP2007250510A (ja) * 2006-02-15 2007-09-27 Sanyo Electric Co Ltd リチウム二次電池用電極及びリチウム二次電池
JP2012190625A (ja) * 2011-03-10 2012-10-04 Hitachi Ltd 非水二次電池
KR20140132292A (ko) * 2013-05-07 2014-11-17 주식회사 엘지화학 이차전지용 전극, 그의 제조방법, 그를 포함하는 이차전지 및 케이블형 이차전지
JP2016058374A (ja) * 2014-09-10 2016-04-21 三菱マテリアル株式会社 リチウムイオン二次電池用正極及びリチウムイオン二次電池

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