Classifications

• • 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
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • 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
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
• • 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
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/002—Inorganic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
• • 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
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
  • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• • 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
  • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
  • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
  • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M6/00—Primary cells; Manufacture thereof
  • H01M6/04—Cells with aqueous electrolyte
  • H01M6/06—Dry cells, i.e. cells wherein the electrolyte is rendered non-fluid
  • H01M6/10—Dry cells, i.e. cells wherein the electrolyte is rendered non-fluid with wound or folded electrodes
• • 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 non-aqueous electrolyte additive for improving safety and a lithium ion secondary battery comprising the same, and more particularly to a non-aqueous electrolyte additive that can improve cycle life and safety properties of a lithium ion secondary battery.
• the lithium ion secondary battery uses a transition metal complex oxide such as lithium, cobalt, etc. as a cathode active material; a crystallized carbon such as graphite as an anode active material; and an aprotic organic solvent in which lithium salts such as LiCIO 4 , LiPF 6 , etc. are dissolved as an electrolyte.
• a transition metal complex oxide such as lithium, cobalt, etc.
• a crystallized carbon such as graphite as an anode active material
• an aprotic organic solvent in which lithium salts such as LiCIO 4 , LiPF 6 , etc. are dissolved as an electrolyte.
• Such a battery has high performance and a light weight, rendering it suitable as a battery for miniature electronic equipment such as cellular phones, camcorders, notebook computers, etc.
• this battery has many safety problems since it does not use an aqueous electrolyte but instead uses a highly flammable organic solvent as an electrolyte.
• Safety is the most important aspect of a lithium ion secondary battery using a non-aqueous electrolyte, and specifically, preventing short circuits and overcharging problems are very important factors thereof.
• the method of stopping a fire of the battery due to a short circuit of the battery have not been well known except a design aspect of the battery.
• the discharge current increases, and therefore the dangerousness due to a short circuit becomes more serious.
• a various additive is developed.
• a method involves using electronic circuit shch as the method a mechanically intercepting a current by aggravating the occurrence of gas when overcharging, or the method shutting down a circuit by melting a separator.
• the method may be effective since overcharge current between a negative electrode and a positive electrode can be consumed, only on condition that reversibility of
• Japanese Patent Publication No. 7-302614 (1995) proposes a new redox shuttle additive applicable in 4V grade, which combines the alkyl group (R:
• the present invention is made in consideration of the problems of the prior art, and it is an object of the present invention to provide a non-aqueous electrolyte additive that can achieve superior safety even under dangerous circumstances caused by misoperation or misuse of the battery, including a large current discharge due to an overcharge or a short circuit in a 4V grade lithium and lithium secondary battery charged with a large current and a high energy density. It is another object of the present invention to provide a lithium ion secondary battery comprising the non-aqueous electrolyte additive.
• the present invention provides a non-aqueous electrolyte additive comprising an organometallic compound represented by the following Chemical Formula 1 :
• R 1 and R 2 which are independently or simultaneously an alkyl group with 1 to 4 carbon atoms, an alkoxy group with 1 to 4 carbon atoms, an acetyl group, a sulfonic acid group, or fluorocarbon, acetoxy, -OSO 3 H, -CF 3 , or a phenyl group or phenoxy group substituted by an alkyl group with 1 to 4 carbon atoms or a halogen;
• M is an atom selected from the group consisting of Al, B, Si, Ti, Nb, V, Cr, Mn, Fe, Co, Ni, Sn, Ga, Zr and Ta;
• x is a valence of a central metal atom;
• y is a value satisfying O ⁇ y ⁇ x-2.
• the present invention also provides a lithium ion secondary battery comprising: a) an anode capable of adsorbing and releasing lithium; b) a cathode capable of adsorbing and releasing lithium; and c) a non-aqueous electrolyte comprising an organometallic compound represented by the above Chemical Formula 1.
• Fig. 1 shows a structure of the lithium ion secondary battery of the present invention.
• Fig. 2 shows change in temperature and voltage of the battery of the Comparative Example, according to overcharge time.
• Fig. 3 shows change in temperature and voltage of the battery of Example 1 of the present invention, according to overcharge time.
• the present invention provides an organometallic compound represented by the above Chemical Formula 1 wherein around the central atom are substituted by a substituent, preferably a phenyl group and oxygen, as a non-aqueous additive for a non-aqueous electrolyte in which a lithium salt is dissolved, for improving safety of a lithium ion secondary battery.
• the present invention provides a lithium ion secondary battery that uses lithium or carbon capable of adsorbing and releasing lithium as an anode, a specific complex oxide of lithium and a transition metal as a cathode, and an organometallic compound represented by the Chemical Formula 1 as a non-aqueous electrolyte. According to the present invention, a large current discharge due to a short circuit or overcharge caused by battery misoperation or misuse can be prevented by a chemical reaction of additives included in a non-aqueous electrolyte, and thus safety of a battery can be improved.
• the organometallic compound represented by the Chemical Formula 1 used as additive for non-aqueous electrolyte in the present invention does not function in a battery operated within the normal voltage range, and thus it does not affect the cycle life properties of the battery.
• additives of the non-aqueous electrolyte of the lithium ion secondary battery that decompose at the surface of the cathode under a completely charged state produce decomposition by-products (preferably benzene-based compounds) that form radicals that polymerize and thereby form an insulating film on a cathode surface.
• decomposition by-products preferably benzene-based compounds
• a metallic inorganic substance of the residue is activated to improve thermal stability of an insulating film formed on the cathode surface.
• coordinators hydrated by hydrolysis with moisture are converted into hydroxy functional groups and react with lithium rushed from the anode to form an insulating film on the cathode surface, thereby giving safety to the battery.
• the organometallic compound represented by the Chemical Formula 1 is preferable benzene-based compound having a stable R 1 , and it is a metal compound that consists of the oxygen having a strong reactivity with a metal, and R 2 having a good affinity with a non-aqueous electrolyte. Therefore, the compound does not function in a battery operated within the normal voltage range. And, since oxygen, a phenyl group and an alkyl group coordinated a metal has superior affinity with a non-aqueous electrolyte, the compound is a good dissolved in the non-aqueous electrolyte, and thus it does not affect the cycle life properties of the battery.
• the compound has oxygen bonded with a metal, and thus if a sudden current such as a large current discharge flows, the compound decreases the diffusion rate of lithium and it reacts with lithium to form an insulating inorganic compound on the cathode surface, thereby improving safety of the battery due to interception of an electron flow.
• the organometallic compound represented by the Chemical Formula 1 if a battery is abnormally overcharged in a non-aqueous electrolyte are decomposed into a benzene-based compound and a metal compound having oxygen. The decomposed benzene-based compound forms an insulating polymer film on the cathode surface to intercept a current due to overcharge, and thus the safety of the battery can be obtained.
• R 1 and R 2 are not a necessity that will be always coexistence, and there are changed by a valance of metal of a central atom due to a bond of a metal of a central atom and oxygen. That is, if the valance of metal is triply-charged, R 1 and R 2 is not coexistence, and thus the compound existing only one of R 1 and R 2 becomes. If the valance of metal is fifth-charged, one of R 1 and R 2 is combined a substituent of 2 or more with the metal of central atom.
• a preferable the compound as a non-aqueous electrolyte additive is a compound that a metal atom is in center and a phenyl group, a sulfonic acid group, a fluorocarbon or an alkyl group with 1 to 4 carbon atoms the around is combined thereto.
• the alkyl group is changed reaction degree according to a value of n, but it is a stable form in an organic solvent. Therefore, a reactivity of the oxygen bonded with the metal existing in the compound changes according to an atom located in center.
• the metal atom bonded with the oxygen easily reacts with activated lithium to form an insulator of a glass configuration.
• the phenyl group of the compound provides a benzene-based compound and activated metal oxide by decomposing when overcharging, and thus a safety of the battery further improves by forming a polymer insulating film and a ceramic insulating film forms due to a benzene-based compound.
• the phenyl group of the compound reacts with lithium deposited in the anode to remove activity of lithium and form a ceramic insulating film, thereby providing effective methods for achieving battery safety.
• R 1 and R 2 of the compound is a sulfonic acid group, or a fluorocarbon, when the compound is decomposed due to overcharge and a large current discharge, the thermal stability of the battery can be improved by forming a fireproofing gas.
• the ceramic insulating film capable of form in the present invention is an amorphous form, and it can be formed a shape of Li 2 O ⁇ MO x (wherein x is
• a non-aqueous electrolyte lithium ion secondary battery comprising the compound represented by the Chemical Formula 1 as a non-aqueous electrolyte additive is prepared.
• the non-aqueous electrolyte lithium secondary battery of the present invention comprises an anode capable of adsorbing and releasing lithium, a cathode capable of adsorbing and releasing lithium, and a non-aqueous electrolyte comprising the compound represented by the Chemical Formula 1.
• the anode and cathode capable of adsorbing and releasing lithium are prepared by a common method, and a non-aqueous electrolyte comprising the compound is injected therein to prepare a secondary battery.
• the active material for the anode capable of adsorbing and releasing lithium is preferably a carbon-based material selected from the group consisting of graphite, carbon fiber, and active carbon.
• the anode further comprises a binder, preferably polyvinylidene fluoride (PVDF).
• a lithium transition metal complex oxide represented by the following Chemical Formula 2 can be used as the active material for the cathode.
• Li x MO 2 wherein M is Ni, Co, or Mn; and x is a value satisfying 0.05 ⁇ x ⁇ 1.10.
• the compound represented by the Chemical Formula 1 used as a non-aqueous electrolyte additive in the, present invention is present at 0.01 to 20 wt% of the electrolyte.
• an aprotic organic solvent wherein lithium salts such as LiCIO 4 , LiPF 6 , LiBF 4 , etc. are dissolved is used.
• the lithium secondary battery of the present invention comprises an anode 1 formed of an anode current collector on which anode active material is coated, and a cathode 2 formed of a cathode current collector on which cathode active material is coated.
• the anode and the cathode are rolled together in a jelly roll configuration with a separator 3 therebetween, an insulator is located at upper and lower sides of the anode and cathode roll, and a can 4 receives it.
• the battery cover 5 is electrically connected to the cathode 2 through a cathode lead, and the can 4 is electrically connected to the anode 1 through an anode lead.
• the cathode lead is welded to a pressure-release valve 6 in which a protuberance selectively seals a pressure-release vent, and thus the cathode lead electrically connects with the battery cover 5 through the pressure-release valve 6.
• a protuberance selectively seals a pressure-release vent
• the cathode lead electrically connects with the battery cover 5 through the pressure-release valve 6.
• Example 1 A non-aqueous electrolyte lithium ion secondary battery was prepared as follows:
• NMP N-methyl-pyrrolidone
• the anode mixture slurry was uniformly coated on both sides of an anode current collector Cu foil at a thickness of 10 /an and dried, and then was compression
• cobalt complex oxide 4 wt% of carbon as a conductor, and 4 wt% of PVDF as a binder were added to a solvent NMP to prepare a cathode mixture slurry.
• the cathode mixture slurry was coated on a cathode current collector Al thin film at a thickness of 20 ⁇ m and dried, and then was compression molded with a roll press to prepare a cathode of a band shape.
• Porous polyethylene film was used as a separator, and the band-shaped anode and the band-shaped cathode were laminated and rolled together in a jelly roll configuration.
• the length and width of the anode and cathode roll were controlled so as to be appropriately received into a battery can of a rectangle with a height of 48 mm, a width of 30 mm, and a thickness of 6.0 mm.
• the anode and cathode roll was deposited in the battery can with insulating plates disposed above and below it.
• an anode lead formed of nickel was attached to the anode current collector and welded to the battery can, and a cathode lead formed of aluminum that was connected to the cathode current collector was welded to an aluminum pressure-relief valve mounted at the battery cover.
• the non-aqueous electrolyte of the present invention was then injected into the fabricated battery.
• a solvent for the non-aqueous electrolyte was a mixed solvent of EC and EMC at a ratio of 1 : 2.
• LiPF 6 was used as an electrolyte, and diphenyl disilanediol was added at 2 wt% of the electrolyte to prepare a non-aqueous electrolyte.
• the fabricated battery was charged to 4.2 V with a constant current of 0.4 mA/cm 2 .
• Standard capacity of a non-aqueous electrolyte secondary battery is 700 mAh and charge/discharge cycles were performed at a rate of 1 C (700 mA/h) with a constant current of from 4.2 V to 3 V.
• a non-aqueous electrolyte secondary battery was fabricated by the same method as in Example 1 , except that compounds shown in Table 1 were used as additives instead of titanium oxide acetyl acetonate.
• a secondary battery was fabricated by the same method as in Example 1 , except that no additive was added to the non-aqueous electrolyte.
• the batteries of Examples 1 to 7 comprising non-aqueous electrolytes to which additives were added did not ignite or explode after having pins passed through them and being short circuited, even after charging. This is because in the additive-added non-aqueous electrolyte, at a large current discharge due to a short circuit, a speed of lithium rushed from an anode is controlled or lithium rushed from an anode reacts with lithium rushed from a cathode surface to form an insulating film on the surface.
• an organometallic compound represented by the Chemical Formula 1 is added to a non-aqueous electrolyte of a battery as an additive, and thus, if a battery voltage is out of normal operation voltage range due to a short circuit and overcharge of the battery, an additive decomposes and a part of the decomposed additive forms an insulating film on a cathode surface, and metal reacts with the insulating film formed on the cathode surface to improve thermal stability of the battery, thereby improving. safety of the battery.

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• 2002
  • 2002-05-22 CN CNB028016920A patent/CN1316671C/zh not_active Expired - Lifetime
  • 2002-05-22 US US10/312,674 patent/US7217477B2/en not_active Expired - Lifetime
  • 2002-05-22 EP EP02730955.8A patent/EP1391003B1/en not_active Expired - Lifetime
  • 2002-05-22 JP JP2002592222A patent/JP3934557B2/ja not_active Expired - Lifetime
  • 2002-05-22 WO PCT/KR2002/000972 patent/WO2002095861A1/en not_active Ceased

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