WO2010058879A1 - Negative active material for lithium secondary battery, method of preparing thereof, and lithium secondary battery including same - Google Patents

Negative active material for lithium secondary battery, method of preparing thereof, and lithium secondary battery including same Download PDF

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Publication number
WO2010058879A1
WO2010058879A1 PCT/KR2008/007913 KR2008007913W WO2010058879A1 WO 2010058879 A1 WO2010058879 A1 WO 2010058879A1 KR 2008007913 W KR2008007913 W KR 2008007913W WO 2010058879 A1 WO2010058879 A1 WO 2010058879A1
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Prior art keywords
active material
negative active
secondary battery
lithium secondary
lithium
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PCT/KR2008/007913
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French (fr)
Inventor
Jaephil Cho
Min Gyu Kim
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Iucf-Hyu (Industry-University Cooperation Foundation Hanyang University)
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Publication of WO2010058879A1 publication Critical patent/WO2010058879A1/en

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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
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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 invention relates to a negative active material for a lithium secondary battery and a lithium secondary battery including the same. More particularly, the present invention relates to a negative active material for a lithium secondary battery having excellent capacity retention and a lithium secondary battery including the same.
  • Lithium secondary batteries generate electrical energy from changes of chemical potential during the intercalation/deintercalation of lithium ions at the positive and negative electrodes.
  • Lithium secondary batteries use materials that reversibly intercalate or deintercalate lithium ions during charge and discharge reactions for both positive and negative active materials, and contain an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.
  • lithium-transition element composite oxides being capable of intercalating lithium such as LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , LiNii. x Co x O 2 (0 ⁇ x ⁇ 1 ), LiMnO 2 , and so on have been researched.
  • negative active materials of a lithium secondary battery various carbon-based materials such as artificial graphite, natural graphite, and hard carbon, which can all intercalate and deintercalate lithium ions, have been used.
  • Graphite of the carbon-based material increases discharge voltage and energy density of a battery because it has a low discharge potential of -0.2V, compared to lithium.
  • a battery using graphite as a negative active material has a high average discharge potential of 3.6V and excellent energy density.
  • graphite is most comprehensively used among the aforementioned carbon-based materials since graphite guarantees better cycle life for a battery due to its outstanding reversibility.
  • a graphite active material has low density (theoretical density of 2.2 g/cc) and consequently low capacity in terms of energy density per unit volume when using the graphite as a negative active material. Further, it involves some dangers such as explosion or combustion when a battery is misused or overcharged and the like, because graphite is likely to react with an organic electrolyte at a high discharge voltage.
  • the examples may include a metal phosphide such as MnP 4 .
  • MnP 4 is redox transferred into Li 7 MnP 4 at 0.57V or more during a first transition, and it has excellent early discharge capacity and charge capacity of 1150mAh/g and 700mAh/g, respectively, but it has a problem of decreasing the capacity to 350 mAh/g after the 10th charge and discharge.
  • the MnP 4 phase provides a cubic Li 7 MnP 4 at 0.5V or more and it is decomposed into Mn and Li 3 P at 0.5V or less, so it causes problems of dramatically deteriorating the reversibility.
  • tertiary Li 2 CuP 2 and Li 7 MP 4 (the M is either Ti or V) has a reversible order or disorder phase transition together with a structural rearrangement during the lithium reaction.
  • tertiary tetragonal Li 5 .5Mn 2 . 5 P 4 does not show a decomposition reaction at OV, and it has a reversible capacity of 700 mAh/g after the 30th charge and discharge.
  • Li metal in the early synthesis, so it is rarely applicable since it impossible to be synthesized in air and it could explode.
  • orthorhombic SnPo. 94 nanoparticles obtained from thermo-decomposition of an organic precursor have shown the reversible intercalation and deintercalation of lithium ions between 1.2 and OV and a speed of 120 mAh/g, and they have early charge and discharge capacities of 850mAh/g and 740mAh/g, respectively, and a high Coulombic efficiency of about 87%.
  • the capacity retention after the 40th charge and discharge is high at 92% based on that of the early charge capacity.
  • orthorhombic SnPo. M has a relatively excellent capacity characteristic and cycle characteristic compared to that of other binary or tertiary phosphides, but it has an insufficient capacity characteristic and cycle-life characteristic.
  • An exemplary embodiment of the present invention provides a negative active material for a lithium secondary battery having excellent capacity retention.
  • Another embodiment of the present invention provides a method of preparing the negative active material.
  • a further embodiment of the present invention provides a lithium secondary battery including the negative active material.
  • a negative active material including a Mo x M y P z compound where M is Co, Mn, Fe, Ni, Zn, or combinations thereof, 0.9 ⁇ x ⁇ 1 , O ⁇ y ⁇ O.1 , and 1.9 ⁇ z ⁇ 2.1.
  • a method of preparing a negative active material for a lithium secondary battery which includes mixing Mo, M metal, and P, and milling the mixture and firing it.
  • a lithium secondary battery including the negative active material.
  • the negative active material has excellent capacity retention. [Brief Description of the Drawings]
  • FIG. 1 is an exploded perspective view of a lithium secondary battery according to one embodiment of the present invention.
  • FIG. 2 is a TEM photograph of the negative active material obtained from Example 1.
  • FIG. 3 is a 100,000 times-magnified enlarged view of the negative active material shown in FIG. 2.
  • FIG. 4 is a graph showing an XRD pattern of the negative active material of which the coin-type half cell obtained from Example 2 was charged and discharged for 60 times at a voltage ranging from 0 to 1.5V.
  • FIG. 5 is a graph showing a voltage profile of the coin half cell obtained from Example 2 when it was charged and discharged at 0 to 1.5V.
  • FIG. 6 is a graph showing a relationship between the charge capacity and the cycle life when the coin-type half cell obtained from Example 2 was charged and discharged at a voltage ranging from 0 to 1.5V. [Best Mode]
  • the negative active material according to one embodiment of the present invention includes a Mo x M y P z compound.
  • M is selected from the group consisting of Co, Mn 1 Fe, Ni, Zn, and combinations thereof. According to one embodiment, Zn is appropriate for M.
  • the M decreases the polarization during the charge and discharge by increasing electrical conductivity.
  • the Mo x M y P z negative active material may be crystalline, amorphous, or a mixture thereof, but in another embodiment, it has a crystalline structure since the structure is more stabilized.
  • the negative active material has a shape of a nanoparticle cluster in which nanoparticles are gathered.
  • the nanoparticles of the nanoparticle cluster have an average particle diameter ranging from 5 to 30 nm, and in another embodiment, it ranges from 5 to 10 nm. Within the range, the diffusion distance of Li ions is decreased, so the intercalation and deintercalation becomes fast.
  • the nanoparticle cluster has an average particle diameter ranging from 5 to 20 ⁇ m, but in another embodiment, it has an average particle diameter ranging from 10 to 20 ⁇ m.
  • the Mo x M y P 2 (M is selected from the group consisting of Co, Mn, Fe, Ni, Zn, and combinations thereof, 0.9 ⁇ x ⁇ 1 , 0 ⁇ y ⁇ 0.1 , and 1.9 ⁇ z ⁇ 2.1 ) compound has excellent reversibility with respect to lithium ions, so the lithium ions are intercalated in Mo x M y P z during the charge and discharge to provide Li,M ⁇ M y P z (0.9 ⁇ x ⁇ 1 , 0 ⁇ y ⁇ 0.1 , 1.9 ⁇ z ⁇ 2.1 , and 0 ⁇ t ⁇ 5) and are then deintercalated, so the reaction to Mo x MyP 2 is easily and reversibly performed. Thereby, it has an excellent cycle-life characteristic. Particularly, when the charge and discharge is repeated at less than 2V, preferably between O and 1.5V, it is structurally stable since it does not cause phase decomposition into an alloy such as LJ 3 P. In addition, the capacity characteristic is excellent.
  • a Mo x MyP z (M is selected from the group consisting of Co, Mn, Fe, Ni, Zn and combinations thereof, 0.9 ⁇ x ⁇ 1 , O ⁇ y ⁇ O.1 , and 1.9 ⁇ z ⁇ 2.1) negative active material according to the present invention may be utilized by mixing it with a carbon-based material, a lithium metal, a lithium metal alloy, a material that is reversibly capable of doping and de-doping with lithium, or a material that is reversibly capable of forming a lithium-included compound or a transition metal oxide.
  • the carbon-based material may be any generally-used carbon-based negative active material for a lithium secondary battery.
  • Examples of the carbon-based material include crystalline carbon such as natural graphite or artificial graphite, and amorphous carbon such as soft carbon and hard carbon.
  • Specific examples include carbon black, acetylene black, activated carbon, carbon fiber, fullerene, single wall carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), carbon nanowire, carbon nanohoms, or carbon nanorings, but are not limited thereto.
  • the lithium metal alloy may be an alloy of lithium and a metal selected from Na, K 1 Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, or combinations thereof.
  • Examples of the material that is reversibly capable of doping and de-doping with lithium and the material that is reversibly capable of forming a lithium-containing compound or transition element oxides include vanadium oxide, lithium vanadium oxide, Si, SiO x (0 ⁇ x ⁇ 2), a Si-Y alloy (Y is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, and combinations thereof, and is not Si), Sn, SnO 2 , and Sn-Y (Y is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, and combinations thereof, and is not Sn).
  • the element Y can be selected from the group consisting of 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, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.
  • the negative active material is prepared by the following process: Mo, M metal, and P are mixed; and the resulting mixture is milled and fired. More particularly, firstly, Mo, metal M, and P are mixed (S1 ).
  • the M is selected from the group consisting of Co, Mn, Fe, Ni, Zn, and a combination thereof.
  • the Mo, metal M, and P may be mixed to reach the molar ratio of x, y, and z defined in Chemical Formula 1.
  • the milling process may be performed at a speed of 800 rpm or below, but in another embodiment, it is performed at a speed ranging from 400 to 800 rpm. When the speed is out of the range, it is not preferable since it may generate impurities such as Fe from the ball used in the milling process.
  • the milling process may be carried out under an inert gas such as argon, helium, neon, xenon (Xe), or a mixed gas thereof, but in another embodiment, it is carried out under the argon gas. This is to prevent the metal that is sensitive to moisture and the metal alloy from reacting with moisture.
  • an inert gas such as argon, helium, neon, xenon (Xe), or a mixed gas thereof, but in another embodiment, it is carried out under the argon gas. This is to prevent the metal that is sensitive to moisture and the metal alloy from reacting with moisture.
  • the firing process may be performed at an appropriate temperature (for example room temperature) for an appropriate duration, and it is not necessary to define a specific firing temperature and firing duration.
  • an appropriate temperature for example room temperature
  • a lithium secondary battery including a negative active material obtained from the method.
  • the lithium secondary battery according to another embodiment of the present invention includes a positive electrode including a positive active material, a negative electrode including a negative active material, and an electrolyte.
  • the negative active material is the same as described above.
  • FIG. 1 is an exploded perspective view of a lithium secondary battery according to one embodiment of the present invention.
  • the lithium secondary battery 1 is constructed of a negative electrode 2, a positive electrode 3, a separator 4 interposed between the negative electrode 2 and the positive electrode 3, and an electrolyte in which the separator 4 is immersed, and further includes a cell case 5 and a sealing member 6 sealing the cell case 5.
  • the negative electrode 2 and the positive electrode 3 may be obtained by forming a composition for a negative electrode including a negative active material and a composition for a positive electrode including a positive active material on a current collector to provide a film mass.
  • the mass is prepared by directly coating the composition for a positive or negative active material on the current collector and drying the same, or casting the composition for an active material on a separate supporter and laminating a film that is delaminated from the supporter on the current collector.
  • composition for forming a negative active material or positive active material may be prepared by dissolving or dispersing the negative active material or the positive active material, a binder, and a conductive agent in a solvent.
  • the negative active material is the same as described above.
  • the positive active material according to the present invention is not specifically limited, and includes a composition that is capable of intercalating/deintercalating lithium ions.
  • the positive active material may include a metal oxide, a lithium composite metal oxide, a lithium composite metal sulfide, and a lithium composite metal nitride.
  • the binder is a chemical material that is stable in the electrochemical reaction, and may play a role of making a paste of the active material, providing adhesion between active materials and between the active material and the current collector, and cushioning the active material from expansion and contraction.
  • the binder includes a water-soluble organic polymer, a non-water-soluble organic polymer, or a mixture thereof.
  • the water-soluble organic polymer includes polyvinyl alcohol, carboxylmethyl cellulose, methyl cellulose, ethyl cellulose, isopropyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cyanoethyl cellulose, ethyl-hydroxyethyl cellulose, polyoxyethylene, polyN-vinylpyrrolidone, polyvinylacetate, or mixtures thereof.
  • the non-water-soluble organic polymer includes polyvinylfluoride, polyvinylidenefluoride, a tetrafluoroethylene polymer, a trifluoroethylene polymer, a difluoroethylene polymer, an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinylether copolymer, a trifluoroethylene chloride polymer, polyethylene, polypropylene, or mixtures thereof.
  • any electrically conductive material can be used as a conductive agent unless it causes a chemical change.
  • the conductive agent include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, a metal powder or a metal fiber including copper, nickel, aluminum, silver, and so on, or a polyphenylene derivative.
  • the conductive agent may have a sphere, flake, filament, fiber, spike, or needle shape. In order to improve tap density, conductive agents having different shapes may be mixed.
  • the solvents include N-methylpyrrolidone (NMP), acetone, tetrahydrofuran, decane, and so on. According to one embodiment, N-methylpyrrolidone may be preferred.
  • the positive active material, negative active material, conductive agent, binder, and solvent may be used in appropriate amounts to fabricate an electrode. Electrode fabrication is well known in this art.
  • the current collector plays a role of collecting electrons generated by the electrochemical reaction of the active material or providing electrons required for the electrochemical reaction.
  • the material for the current collector may include one that is treated with carbon, nickel, or titanium on the surface of copper or stainless steel, as well as stainless steel, aluminum, nickel, copper, titanium, carbon, and a conductive resin.
  • the positive electrode includes an aluminum current collector and the negative electrode includes a copper current collector.
  • the electrolyte transfers lithium ions between positive and negative electrodes.
  • a non-aqueous electrolyte or a solid electrolyte may be used.
  • the non-aqueous electrolyte includes a non-aqueous organic solvent wherein lithium salts are dissolved.
  • the lithium salts include LiCIO 4 , LiBF 4 , LiPF 6 , LiAICI 4 , LiSbF 6 , LiSCN,
  • the non-aqueous organic solvent acts as a medium for transmitting ions taking part in the electrochemical reaction of the battery.
  • the non-aqueous organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and the like; linear carbonates such as dimethyl carbonate, methylethyl carbonate, diethyl carbonate, and the like; esters such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, Y -butyrolactone, and the like; ethers such as 1 ,2-dimethoxyethane, 1 ,2-diethoxyethane, tetrahydrofuran, 1 ,2-dioxane, 2-methyltetrahydrofuran, and the like; nitriles such as acetonitrile; amides such as dimethylformamide; and the like.
  • These solvent may
  • the solid electrolytes include Li 4 SiO 4 , Li 4 SiO 4 -LiI-LiOH, Li 2 SiSa, Li 3 PO 4 -Li 2 S-SiS 2 , a phosphorous sulfide compound, polyethylene oxide (PEO) 1 polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyvinylidene fluoride (PVDF), and mixtures thereof.
  • the lithium secondary battery 1 including the above constituents blocks electron conductivity between the negative electrode 2 and the positive electrode 3, and includes the separator 4 that is capable of conducting lithium ions.
  • the separator 4 plays an important role in improving the stability as well as separating the positive electrode from the negative electrode.
  • the separator may include any material that is commonly available for a lithium secondary battery, and for example it includes polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer of two or more layers thereof.
  • the lithium secondary battery according to the present invention having the constituents may be formed as a coin, button, sheet, laminate, cylindrical, plain, or prismatic type, and it can be suitably designed by one having ordinary skills in this field.
  • the lithium secondary battery according to the present invention may be applicable to a portable information terminal, a portable electronic device, a domestic small electric power storing device, a conventional vehicle, an electric vehicle, a hybrid electric vehicle, and so on.
  • Example 1 Preparing Negative Active Material Mo (manufactured by Aldrich, 99.9%) and P (manufactured by Aldrich, 99.9%) were introduced into a 200ml of stainless steel container in a stoichiometric amount of 3Og. The molar ratio of Mo and P was set to 1 :2. A steel ball was introduced in the stainless steel container to satisfy a weight ratio of MoP 2 to the steel ball of 1 :30.
  • Example 2 Fabricating Lithium Secondary Cell> 80 wt% of a MoP 2 active material obtained from Example 1 , 10 wt% of a polyvinylidene fluoride binder, and 10 wt% of Super P carbon black conductive agent were mixed and coated on a copper current collector to provide a negative electrode.
  • FIG. 2 shows a TEM photograph of the negative active material obtained from Example 1
  • FIG. 3 shows a 100,000-times magnified view thereof.
  • the negative active material obtained from Example 1 had a shape of a nanoparticle cluster having an average particle size of 5 ⁇ m and including nanoparticles having an average particle diameter of 10 nm.
  • SADP selected area diffraction pattern
  • FIG. 4 shows an XRD pattern of a negative active material of a coin-type half cell obtained from Example 2 that was charged and discharged at a voltage of 0 to 1 .5V and a speed of 0.1 C for 60 cycles. As shown in FIG. 4, it is confirmed that there was only a peak of MoP 2 after the 60th charge and discharge.
  • phase decomposition did not occur when it was charged and discharged at a cut-off voltage of 1 .5V.
  • FIG. 5 shows the voltage profile of a coin-type half cell obtained from
  • Example 2 that was charged and discharged at 0 to 1.5V and a speed of 0.2 C when it was charged and discharged for 1 , 10, 20, 30, and 60 cycles; and FIG. 6 shows the relationship between charge capacity and cycle-life of coin-type half cell obtained from Example 2 that was charged and discharged at a voltage of 0 to 1.5V and a speed of 0.2C.
  • the first discharge capacity and the first charge capacity were 817mAh/g and 719mAh/g, respectively; the Coulombic efficiency was approximate 88%; the reversible capacity was 669 mAh/g after the 60th charge and discharge; and the capacity retention was high at approximately 93%.
  • the MoP 2 according to Example 1 was not decomposed into Li n P after the 60th charge and discharge, even at OV.
  • the coin-type half cell according to Comparative Example 1 had a discharge capacity of 164 mAh/g at the 50th charge and discharge and capacity retention of 20%; and it had a discharge capacity of 100 mAh/g at the 60th charge and discharge and capacity retention of 12.16.

Abstract

The present invention relates to a negative active material for a lithium secondary battery and a lithium secondary battery including the same. The negative active material includes a MoxMyPzcompound where M is Co, Mn, Fe, Ni, Zn, or combinations thereof, 0.9 ≤x≤ 1, O ≤y≤ O.1, and 1.9 <z <2.1. The negative active material has excellent capacity retention.

Description

[Invention Title]
NEGATIVE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY, METHOD OF PREPARING THEREOF, AND LITHIUM SECONDARY
BATTERY INCLUDING SAME [Technical Field]
The present invention relates to a negative active material for a lithium secondary battery and a lithium secondary battery including the same. More particularly, the present invention relates to a negative active material for a lithium secondary battery having excellent capacity retention and a lithium secondary battery including the same.
This work was supported by the IT R&D program of MKE/IITA (Core Lithium secondary battery Negative Active Materials for Next Generation Mobile Power Module, 2008-F-019-01). [Background Art] In recent times, due to reductions in size and weight of portable electronic equipment, there has been a need to develop batteries for use in the portable electronic equipment, where the batteries have both high performance and large capacity.
Batteries generate electric power using an electrochemical reaction material (referred to hereinafter simply as "active material") for a positive electrode and a negative electrode. Lithium secondary batteries generate electrical energy from changes of chemical potential during the intercalation/deintercalation of lithium ions at the positive and negative electrodes. Lithium secondary batteries use materials that reversibly intercalate or deintercalate lithium ions during charge and discharge reactions for both positive and negative active materials, and contain an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode. For positive active materials of a lithium secondary battery, lithium-transition element composite oxides being capable of intercalating lithium such as LiCoO2, LiMn2O4, LiNiO2, LiNii.xCoxO2 (0<x<1 ), LiMnO2, and so on have been researched.
As for negative active materials of a lithium secondary battery, various carbon-based materials such as artificial graphite, natural graphite, and hard carbon, which can all intercalate and deintercalate lithium ions, have been used. Graphite of the carbon-based material increases discharge voltage and energy density of a battery because it has a low discharge potential of -0.2V, compared to lithium. A battery using graphite as a negative active material has a high average discharge potential of 3.6V and excellent energy density. Furthermore, graphite is most comprehensively used among the aforementioned carbon-based materials since graphite guarantees better cycle life for a battery due to its outstanding reversibility. However, a graphite active material has low density (theoretical density of 2.2 g/cc) and consequently low capacity in terms of energy density per unit volume when using the graphite as a negative active material. Further, it involves some dangers such as explosion or combustion when a battery is misused or overcharged and the like, because graphite is likely to react with an organic electrolyte at a high discharge voltage.
In order to solve these problems, a great deal of research on non-carbon-based negative active materials has recently been performed. The examples may include a metal phosphide such as MnP4. MnP4 is redox transferred into Li7MnP4 at 0.57V or more during a first transition, and it has excellent early discharge capacity and charge capacity of 1150mAh/g and 700mAh/g, respectively, but it has a problem of decreasing the capacity to 350 mAh/g after the 10th charge and discharge.
In addition, the MnP4 phase provides a cubic Li7MnP4 at 0.5V or more and it is decomposed into Mn and Li3P at 0.5V or less, so it causes problems of dramatically deteriorating the reversibility. As opposed to a binary MPn system, tertiary Li2CuP2 and Li7MP4 (the M is either Ti or V) has a reversible order or disorder phase transition together with a structural rearrangement during the lithium reaction.
In addition, tertiary tetragonal Li5.5Mn2.5P4 does not show a decomposition reaction at OV, and it has a reversible capacity of 700 mAh/g after the 30th charge and discharge. However, it should use Li metal in the early synthesis, so it is rarely applicable since it impossible to be synthesized in air and it could explode.
Recently, orthorhombic SnPo.94 nanoparticles obtained from thermo-decomposition of an organic precursor have shown the reversible intercalation and deintercalation of lithium ions between 1.2 and OV and a speed of 120 mAh/g, and they have early charge and discharge capacities of 850mAh/g and 740mAh/g, respectively, and a high Coulombic efficiency of about 87%. In addition, the capacity retention after the 40th charge and discharge is high at 92% based on that of the early charge capacity. In the other words, orthorhombic SnPo.M has a relatively excellent capacity characteristic and cycle characteristic compared to that of other binary or tertiary phosphides, but it has an insufficient capacity characteristic and cycle-life characteristic.
[DETAILED DESCRIPTION]
[Technical Problem]
An exemplary embodiment of the present invention provides a negative active material for a lithium secondary battery having excellent capacity retention.
[Technical Solution]
Another embodiment of the present invention provides a method of preparing the negative active material.
A further embodiment of the present invention provides a lithium secondary battery including the negative active material.
The embodiments of the present invention are not limited to the above technical purposes, and a person of ordinary skill in the art can understand other technical purposes.
According to one embodiment of the present invention, provided is a negative active material including a MoxMyPz compound where M is Co, Mn, Fe, Ni, Zn, or combinations thereof, 0.9≤x≤ 1 , O≤y≤O.1 , and 1.9≤z≤2.1.
According to another embodiment of the present invention, provided is a method of preparing a negative active material for a lithium secondary battery, which includes mixing Mo, M metal, and P, and milling the mixture and firing it. According to a further embodiment of the present invention, provided is a lithium secondary battery including the negative active material. [Advantageous Effects]
The negative active material has excellent capacity retention. [Brief Description of the Drawings]
FIG. 1 is an exploded perspective view of a lithium secondary battery according to one embodiment of the present invention.
FIG. 2 is a TEM photograph of the negative active material obtained from Example 1. FIG. 3 is a 100,000 times-magnified enlarged view of the negative active material shown in FIG. 2.
FIG. 4 is a graph showing an XRD pattern of the negative active material of which the coin-type half cell obtained from Example 2 was charged and discharged for 60 times at a voltage ranging from 0 to 1.5V. FIG. 5 is a graph showing a voltage profile of the coin half cell obtained from Example 2 when it was charged and discharged at 0 to 1.5V.
FIG. 6 is a graph showing a relationship between the charge capacity and the cycle life when the coin-type half cell obtained from Example 2 was charged and discharged at a voltage ranging from 0 to 1.5V. [Best Mode]
Exemplary embodiments of the present invention will hereinafter be described in detail. However, these embodiments are only exemplary, and the present invention is not limited thereto.
The negative active material according to one embodiment of the present invention includes a MoxMyPz compound.
M is selected from the group consisting of Co, Mn1 Fe, Ni, Zn, and combinations thereof. According to one embodiment, Zn is appropriate for M. The M decreases the polarization during the charge and discharge by increasing electrical conductivity.
In addition, according to one embodiment, 0.9≤x≤ 1 , O≤y≤O.1 , and
1.9≤z<2.1 , and according to another embodiment, 0.97<x< 1 , 0≤y≤0.05 and 1.98 ≤ z < 2. When x, y, and z are within the ranges, structural stabilization can be accomplished. Furthermore, the MoxMyPz negative active material may be crystalline, amorphous, or a mixture thereof, but in another embodiment, it has a crystalline structure since the structure is more stabilized.
According to one embodiment, the negative active material has a shape of a nanoparticle cluster in which nanoparticles are gathered. According to one embodiment, the nanoparticles of the nanoparticle cluster have an average particle diameter ranging from 5 to 30 nm, and in another embodiment, it ranges from 5 to 10 nm. Within the range, the diffusion distance of Li ions is decreased, so the intercalation and deintercalation becomes fast. In addition, according to one embodiment, the nanoparticle cluster has an average particle diameter ranging from 5 to 20 μ m, but in another embodiment, it has an average particle diameter ranging from 10 to 20 μ m.
Within the range, the electrode plate density is improved. The MoxMyP2 (M is selected from the group consisting of Co, Mn, Fe, Ni, Zn, and combinations thereof, 0.9≤x≤ 1 , 0≤y<0.1 , and 1.9<z<2.1 ) compound has excellent reversibility with respect to lithium ions, so the lithium ions are intercalated in MoxMyPz during the charge and discharge to provide Li,MθχMyPz (0.9<x< 1 , 0 <y<0.1 , 1.9<z<2.1 , and 0<t<5) and are then deintercalated, so the reaction to MoxMyP2 is easily and reversibly performed. Thereby, it has an excellent cycle-life characteristic. Particularly, when the charge and discharge is repeated at less than 2V, preferably between O and 1.5V, it is structurally stable since it does not cause phase decomposition into an alloy such as LJ3P. In addition, the capacity characteristic is excellent.
A MoxMyPz (M is selected from the group consisting of Co, Mn, Fe, Ni, Zn and combinations thereof, 0.9≤x≤ 1 , O≤y≤O.1 , and 1.9≤z<2.1) negative active material according to the present invention may be utilized by mixing it with a carbon-based material, a lithium metal, a lithium metal alloy, a material that is reversibly capable of doping and de-doping with lithium, or a material that is reversibly capable of forming a lithium-included compound or a transition metal oxide.
The carbon-based material may be any generally-used carbon-based negative active material for a lithium secondary battery. Examples of the carbon-based material include crystalline carbon such as natural graphite or artificial graphite, and amorphous carbon such as soft carbon and hard carbon.
Specific examples include carbon black, acetylene black, activated carbon, carbon fiber, fullerene, single wall carbon nanotubes (SWNT), multi-walled carbon nanotubes (MWNT), carbon nanowire, carbon nanohoms, or carbon nanorings, but are not limited thereto.
The lithium metal alloy may be an alloy of lithium and a metal selected from Na, K1 Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, or combinations thereof. Examples of the material that is reversibly capable of doping and de-doping with lithium and the material that is reversibly capable of forming a lithium-containing compound or transition element oxides include vanadium oxide, lithium vanadium oxide, Si, SiOx (0 < x < 2), a Si-Y alloy (Y is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, and combinations thereof, and is not Si), Sn, SnO2, and Sn-Y (Y is an element selected from the group consisting of an alkali metal, an alkaline-earth metal, a group 13 element, a group 14 element, a transition element, a rare earth element, and combinations thereof, and is not Sn). At least one of the above materials may be mixed with SiO2. The element Y can be selected from the group consisting of 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, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, and combinations thereof.
The negative active material is prepared by the following process: Mo, M metal, and P are mixed; and the resulting mixture is milled and fired. More particularly, firstly, Mo, metal M, and P are mixed (S1 ). The M is selected from the group consisting of Co, Mn, Fe, Ni, Zn, and a combination thereof.
The Mo, metal M, and P may be mixed to reach the molar ratio of x, y, and z defined in Chemical Formula 1.
Subsequently, the mixture is milled and fired (S2).
The milling process may be performed at a speed of 800 rpm or below, but in another embodiment, it is performed at a speed ranging from 400 to 800 rpm. When the speed is out of the range, it is not preferable since it may generate impurities such as Fe from the ball used in the milling process.
The milling process may be carried out under an inert gas such as argon, helium, neon, xenon (Xe), or a mixed gas thereof, but in another embodiment, it is carried out under the argon gas. This is to prevent the metal that is sensitive to moisture and the metal alloy from reacting with moisture.
The firing process may be performed at an appropriate temperature (for example room temperature) for an appropriate duration, and it is not necessary to define a specific firing temperature and firing duration.
According to one embodiment, provided is a lithium secondary battery including a negative active material obtained from the method.
The lithium secondary battery according to another embodiment of the present invention includes a positive electrode including a positive active material, a negative electrode including a negative active material, and an electrolyte. The negative active material is the same as described above.
FIG. 1 is an exploded perspective view of a lithium secondary battery according to one embodiment of the present invention. Referring to FIG. 1 , the lithium secondary battery 1 is constructed of a negative electrode 2, a positive electrode 3, a separator 4 interposed between the negative electrode 2 and the positive electrode 3, and an electrolyte in which the separator 4 is immersed, and further includes a cell case 5 and a sealing member 6 sealing the cell case 5. The negative electrode 2 and the positive electrode 3 may be obtained by forming a composition for a negative electrode including a negative active material and a composition for a positive electrode including a positive active material on a current collector to provide a film mass. The mass is prepared by directly coating the composition for a positive or negative active material on the current collector and drying the same, or casting the composition for an active material on a separate supporter and laminating a film that is delaminated from the supporter on the current collector.
The composition for forming a negative active material or positive active material may be prepared by dissolving or dispersing the negative active material or the positive active material, a binder, and a conductive agent in a solvent. The negative active material is the same as described above.
The positive active material according to the present invention is not specifically limited, and includes a composition that is capable of intercalating/deintercalating lithium ions. Representatively, the positive active material may include a metal oxide, a lithium composite metal oxide, a lithium composite metal sulfide, and a lithium composite metal nitride.
The binder is a chemical material that is stable in the electrochemical reaction, and may play a role of making a paste of the active material, providing adhesion between active materials and between the active material and the current collector, and cushioning the active material from expansion and contraction. The binder includes a water-soluble organic polymer, a non-water-soluble organic polymer, or a mixture thereof. The water-soluble organic polymer includes polyvinyl alcohol, carboxylmethyl cellulose, methyl cellulose, ethyl cellulose, isopropyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cyanoethyl cellulose, ethyl-hydroxyethyl cellulose, polyoxyethylene, polyN-vinylpyrrolidone, polyvinylacetate, or mixtures thereof. The non-water-soluble organic polymer includes polyvinylfluoride, polyvinylidenefluoride, a tetrafluoroethylene polymer, a trifluoroethylene polymer, a difluoroethylene polymer, an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a tetrafluoroethylene-perfluoroalkyl vinylether copolymer, a trifluoroethylene chloride polymer, polyethylene, polypropylene, or mixtures thereof.
Any electrically conductive material can be used as a conductive agent unless it causes a chemical change. Examples of the conductive agent include natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, a metal powder or a metal fiber including copper, nickel, aluminum, silver, and so on, or a polyphenylene derivative. The conductive agent may have a sphere, flake, filament, fiber, spike, or needle shape. In order to improve tap density, conductive agents having different shapes may be mixed.
The solvents include N-methylpyrrolidone (NMP), acetone, tetrahydrofuran, decane, and so on. According to one embodiment, N-methylpyrrolidone may be preferred.
The positive active material, negative active material, conductive agent, binder, and solvent may be used in appropriate amounts to fabricate an electrode. Electrode fabrication is well known in this art.
The current collector plays a role of collecting electrons generated by the electrochemical reaction of the active material or providing electrons required for the electrochemical reaction. The material for the current collector may include one that is treated with carbon, nickel, or titanium on the surface of copper or stainless steel, as well as stainless steel, aluminum, nickel, copper, titanium, carbon, and a conductive resin. According to one embodiment, the positive electrode includes an aluminum current collector and the negative electrode includes a copper current collector.
The electrolyte transfers lithium ions between positive and negative electrodes. For the electrolyte, a non-aqueous electrolyte or a solid electrolyte may be used. For example, the non-aqueous electrolyte includes a non-aqueous organic solvent wherein lithium salts are dissolved. The lithium salts include LiCIO4, LiBF4, LiPF6, LiAICI4, LiSbF6, LiSCN,
LiCI, LiCF3SO3, LiCF3CO2, Li(CF3SO2)S, LiAsF6, LiN(CF3SO2)2, LiB10CIi0, LiCI, LiBr, LiI, and mixtures thereof.
The non-aqueous organic solvent acts as a medium for transmitting ions taking part in the electrochemical reaction of the battery. Examples of the non-aqueous organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and the like; linear carbonates such as dimethyl carbonate, methylethyl carbonate, diethyl carbonate, and the like; esters such as methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, Y -butyrolactone, and the like; ethers such as 1 ,2-dimethoxyethane, 1 ,2-diethoxyethane, tetrahydrofuran, 1 ,2-dioxane, 2-methyltetrahydrofuran, and the like; nitriles such as acetonitrile; amides such as dimethylformamide; and the like. These solvent may be used singularly or in combination. According to one embodiment, a mixed solvent of a cyclic carbonate and a linear carbonate is preferred.
The solid electrolytes include Li4SiO4, Li4SiO4-LiI-LiOH, Li2SiSa, Li3PO4-Li2S-SiS2, a phosphorous sulfide compound, polyethylene oxide (PEO)1 polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyvinylidene fluoride (PVDF), and mixtures thereof. The lithium secondary battery 1 including the above constituents blocks electron conductivity between the negative electrode 2 and the positive electrode 3, and includes the separator 4 that is capable of conducting lithium ions. The separator 4 plays an important role in improving the stability as well as separating the positive electrode from the negative electrode. The separator may include any material that is commonly available for a lithium secondary battery, and for example it includes polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer of two or more layers thereof.
The lithium secondary battery according to the present invention having the constituents may be formed as a coin, button, sheet, laminate, cylindrical, plain, or prismatic type, and it can be suitably designed by one having ordinary skills in this field.
In addition, the lithium secondary battery according to the present invention may be applicable to a portable information terminal, a portable electronic device, a domestic small electric power storing device, a conventional vehicle, an electric vehicle, a hybrid electric vehicle, and so on. [Mode of the Invention]
The following examples illustrate the present invention in more detail. However, it is understood that the present invention is not limited by these examples.
<Example 1 : Preparing Negative Active Material Mo (manufactured by Aldrich, 99.9%) and P (manufactured by Aldrich, 99.9%) were introduced into a 200ml of stainless steel container in a stoichiometric amount of 3Og. The molar ratio of Mo and P was set to 1 :2. A steel ball was introduced in the stainless steel container to satisfy a weight ratio of MoP2 to the steel ball of 1 :30.
The container was sealed in a glove box filled with pure argon gas and revolved at a speed of 800 rpm with a high speed milling machine for 10 hours to provide an active material of MoP2. From the analysis results of ICP-MS (inductively coupled plasma-mass spectroscopy), it is understood that the molar ratio of P to Mo in the MoP2 active material was 2.01 :1.00. <Example 2: Fabricating Lithium Secondary Cell> 80 wt% of a MoP2 active material obtained from Example 1 , 10 wt% of a polyvinylidene fluoride binder, and 10 wt% of Super P carbon black conductive agent were mixed and coated on a copper current collector to provide a negative electrode.
With the negative electrode, a microporous polyethylene separator, and an electrolyte solution of which 1.05M LiPF6 was dissolved in ethylene carbonate / diethylene carbonate / ethylmethyl carbonate (EC/DEC/EMC = 30:30:40 volume%), a 2016 coin-type half cell was fabricated.
<Comparative Example 1 >
Commercially available MoP2 (manufactured by Selic) having a particle diameter of 20 urn or more was used as a negative active material, and a 2016 coin-type half cell was fabricated in accordance with the same procedure as in Example 2.
TEM Photograph
FIG. 2 shows a TEM photograph of the negative active material obtained from Example 1 , and FIG. 3 shows a 100,000-times magnified view thereof. Referring to FIG. 2, it is confirmed that the negative active material obtained from Example 1 had a shape of a nanoparticle cluster having an average particle size of 5 μ m and including nanoparticles having an average particle diameter of 10 nm. In addition, from the SADP (selected area diffraction pattern) result inserted in FIG. 3, a MoP2 crystalline shape was confirmed.
X-ray Diffraction Measurement
FIG. 4 shows an XRD pattern of a negative active material of a coin-type half cell obtained from Example 2 that was charged and discharged at a voltage of 0 to 1 .5V and a speed of 0.1 C for 60 cycles. As shown in FIG. 4, it is confirmed that there was only a peak of MoP2 after the 60th charge and discharge.
From the above, it is confirmed that the phase decomposition did not occur when it was charged and discharged at a cut-off voltage of 1 .5V.
Cycle-life Characteristic Coin-type half cells obtained from Example 2 and Comparative Example
1 were charged and discharged at 0 to 1.5V and a speed of 0.2C (=160mAh/g) to measure the voltage profile and the relationship between charge capacity and cycle-life. The results of Example 2 are shown in FIGS. 5 and 6. FIG. 5 shows the voltage profile of a coin-type half cell obtained from
Example 2 that was charged and discharged at 0 to 1.5V and a speed of 0.2 C when it was charged and discharged for 1 , 10, 20, 30, and 60 cycles; and FIG. 6 shows the relationship between charge capacity and cycle-life of coin-type half cell obtained from Example 2 that was charged and discharged at a voltage of 0 to 1.5V and a speed of 0.2C.
As shown in FIGS. 5 and 6, the first discharge capacity and the first charge capacity were 817mAh/g and 719mAh/g, respectively; the Coulombic efficiency was approximate 88%; the reversible capacity was 669 mAh/g after the 60th charge and discharge; and the capacity retention was high at approximately 93%. Differing from other metal phosphides, the MoP2 according to Example 1 was not decomposed into LinP after the 60th charge and discharge, even at OV.
However, the coin-type half cell according to Comparative Example 1 had a discharge capacity of 164 mAh/g at the 50th charge and discharge and capacity retention of 20%; and it had a discharge capacity of 100 mAh/g at the 60th charge and discharge and capacity retention of 12.16.
Accordingly, it is confirmed that the capacity retention was remarkably deteriorated compared to that of Example 2.
That is, while other binary metal phosphides such as in Comparative Example 1 rapidly decreased in terms of capacity, it is confirmed that MoP2 improved the cycle-life stability. Such improved cycle-life stability and capacity retention shows that the Li reaction of MoP2 was different from that of other metal phosphides.
While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

[CLAIMS] [Claim 1 ]
A negative active material comprising a MoxMyPz compound where M is Co, Mn, Fe, Ni, Zn, or combinations thereof, 0.9<x< 1 , O≤y≤O.1 , and 1 .9 <z < 2.1.
[Claim 2]
The negative active material of claim 1 , wherein the negative active material has a nanoparticle cluster shape.
[Claim 3]
The negative active material of claim 1 , wherein M is Zn.
[Claim 4] The negative active material of claim 2, wherein the nanoparticle cluster has an average particle diameter of 5 to 30nm.
[Claim 5]
The negative active material of claim 2, wherein the nanoparticle cluster has an average particle diameter of 5 to 20 μ m.
[Claim 6]
A method of preparing a negative active material for a lithium secondary battery, comprising: mixing Mo, M metal, and P; and milling the mixture and firing it.
[Claim 7]
A lithium secondary battery comprising: a positive electrode including a positive active material; a negative electrode including a negative active material; and an electrolyte, wherein the negative active material comprises a MoxMyPz compound where M is Co, Mn, Fe, Ni, Zn, or combinations thereof, 0.9≤x≤ 1 , O≤y≤O.1 , and 1.9<z<2.1.
[Claim 8] The lithium secondary battery of claim 7, wherein the negative active material has a nanoparticle cluster shape.
[Claim 9]
The lithium secondary battery of claim 7, wherein M is Zn.
[Claim 10]
The lithium secondary battery of claim 8, wherein the nanoparticle cluster has an average particle diameter of 5 to 30nm. [Claim 11 ]
The lithium secondary battery of claim 8, wherein the nanoparticle cluster has an average particle diameter 5 to 20 μ m.
PCT/KR2008/007913 2008-11-19 2008-12-31 Negative active material for lithium secondary battery, method of preparing thereof, and lithium secondary battery including same WO2010058879A1 (en)

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KR101631914B1 (en) * 2013-11-19 2016-06-20 한국전기연구원 Anode Active Materials comprising Mo-Si-P Systems For Li Ion Batteries And Manufacturing Methods Thereof
KR102292531B1 (en) * 2014-11-17 2021-08-25 한국전기연구원 Anode Active Materials comprising Si or Si Alloy Systems With MoP Coating For Li Ion Batteries, And Anodes comprising The Same And Manufacturing Methods Thereof
KR102292533B1 (en) * 2015-10-26 2021-08-24 한국전기연구원 Anode Active CoP Composite Materials System Comprising MoP For Li Ion Batteries, And Anodes comprising The Same And Manufacturing Methods Thereof

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