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WO2014077118A1 - Cathode et élément rechargeable non aqueux - Google Patents

Cathode et élément rechargeable non aqueux Download PDF

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Publication number
WO2014077118A1
WO2014077118A1 PCT/JP2013/079213 JP2013079213W WO2014077118A1 WO 2014077118 A1 WO2014077118 A1 WO 2014077118A1 JP 2013079213 W JP2013079213 W JP 2013079213W WO 2014077118 A1 WO2014077118 A1 WO 2014077118A1
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WIPO (PCT)
Prior art keywords
positive electrode
active material
electrode active
volume change
battery
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PCT/JP2013/079213
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English (en)
Japanese (ja)
Inventor
耕司 大平
貴洋 松山
俊平 西中
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シャープ株式会社
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Publication of WO2014077118A1 publication Critical patent/WO2014077118A1/fr

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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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/26—Phosphates
    • C01B25/45—Phosphates containing plural metal, or metal and ammonium
    • 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
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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 positive electrode and a non-aqueous secondary battery. More specifically, the present invention relates to a positive electrode capable of providing a non-aqueous secondary battery excellent in safety and cycle characteristics, and a non-aqueous secondary battery using the positive electrode.
  • lithium secondary batteries are attracting attention not only as small-sized batteries for portable electronic devices but also as large-capacity batteries for in-vehicle use and power storage. For this reason, demands for safety, cost, and lifetime are increasing.
  • lithium iron phosphate (LiFePO 4 ) having an olivine structure has attracted attention from the viewpoint of safety and cost.
  • the olivine structure is a structure in which phosphorus and oxygen are covalently bonded, so that it is essentially difficult to desorb oxygen up to a high temperature, and high safety can be obtained. Further, the olivine structure does not use Co or Ni, and therefore has an advantage in terms of cost.
  • lithium iron phosphate has a specific behavior that it has a flat potential behavior because a two-phase reaction proceeds with the insertion and removal of Li.
  • lithium iron phosphate is a positive electrode active material having characteristic characteristics, a method of using a mixture of other positive electrode active materials has been proposed.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2007-250299 proposes detecting the remaining battery capacity by utilizing the flat potential of lithium iron phosphate.
  • Patent Document 2 Japanese Patent Laid-Open No. 2010-27409
  • Patent Document 3 Japanese Patent Publication No. 2010-517238 proposes mixing lithium iron phosphate in order to improve battery safety.
  • the volume change rate accompanying the insertion and desorption of Li is about 7%, and the volume change rate is higher than the volume change rate of a general positive electrode active material. Yes.
  • the volume change of the electrode accompanying charging / discharging is large, the stress concerning the inside of an electrode becomes large, and the deterioration accompanying charging / discharging tends to arise.
  • an object of the present invention is to provide a positive electrode capable of relieving stress inside the electrode and realizing a long life while using a positive electrode active material having an olivine structure excellent in safety and cost.
  • the positive electrode of the present invention includes two or more positive electrode active materials having different volume change rates during charge and discharge, and the two or more positive electrode active materials have an olivine structure. It is said.
  • the volume change rate at the time of charging / discharging of at least 1 sort (s) of positive electrode active materials of the said 2 or more types of positive electrode active materials is smaller than the volume change rate at the time of charging / discharging of lithium iron phosphate.
  • the mass of the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate is 30% or more with respect to the mass of the total positive electrode active material.
  • the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate has an olivine structure and has a general formula (Li 1-x A x Fe 1 represented by -y M y P 1-z Si z O 4).
  • A is at least one of Na, Fe, and M
  • M is any of Ti, V, Nb, Al, Y, Zr, and Sn
  • x Is 0 ⁇ x ⁇ 0.25
  • y is 0 ⁇ y ⁇ 0.25
  • z is 0 ⁇ z ⁇ 0.25.
  • the non-aqueous secondary battery of the present invention is characterized by including the positive electrode.
  • a positive electrode active material having an olivine structure that has an olivine structure and has two or more positive electrode active materials having different volume change rates at the time of charge and discharge, thereby providing superior safety and cost.
  • the positive electrode active material having a smaller volume change rate can relieve stress inside the electrode, prevent the conductive path from being broken, suppress the decrease in electric capacity, and realize a long life.
  • FIG. 5 is a view showing a list of compositions and volume change rates of positive electrode active materials A1 to A5. It is a figure which shows the list of the initial capacity of each Example and a comparative example, and the storage capacity after charging / discharging. It is a graph which shows the relationship between a volume change rate and the capacity
  • A is at least one selected from Li, Na, and Groups 3 to 13
  • M is at least one selected from Groups 3 to 13
  • X Is at least one selected from Al, Si, and P.
  • a, b, and c are ranges of 0 ⁇ a ⁇ 2, 0 ⁇ b ⁇ 2, and 0 ⁇ c ⁇ 2, respectively.
  • the positive electrode active material is a material having an olivine structure in addition to the composition represented by the general formula (1).
  • A is Li or Na
  • M is at least one of Mn, Fe, Co, and Ni
  • X is P.
  • a substance is known.
  • LiFePO 4, LiMnPO 4, LiCoPO 4, LiNiPO 4, NaFePO 4, NaMnPO 4, NaCoPO 4, include materials represented by the composition of NaNiPO 4.
  • lithium iron phosphate LiFePO 4
  • LiMnPO 4 lithium manganese phosphate
  • the second positive electrode active material having a smaller volume change rate during charge / discharge than the first positive electrode active material
  • a positive electrode active material in which at least one of Li, Fe, and P of lithium iron phosphate (LiFePO 4 ) is substituted with another element can be used.
  • examples of the second positive electrode active material include those represented by the following general formula (2) and general formula (3).
  • A is at least one of Na, Fe, and M
  • M is any of Ti, V, Nb, Al, Y, Zr, and Sn.
  • lithium iron phosphate (LiFePO 4) as the first positive electrode active material was obtained. 4 ) Charging / discharging is performed at the same potential as in ( 4 ). Therefore, even when the first positive electrode active material and the second positive electrode active material are mixed and used, the first positive electrode active material and the second positive electrode active material can be used for a battery without worrying about potential change.
  • the amount of Li that can be reacted is reduced by element substitution, so that the theoretical capacity is reduced.
  • the amount of reacting Li decreases and the theoretical capacity decreases, the volume change can be suppressed and the effect that electrode peeling can be suppressed can be obtained remarkably.
  • by mixing the first positive electrode active material and the second positive electrode active material it is possible to suppress a decrease in theoretical capacity and to suppress a volume change during charging / discharging, thereby prolonging the life and high battery capacity. Maintenance can be realized.
  • Non-aqueous secondary battery includes a positive electrode, a negative electrode, an electrolyte, and a separator.
  • a positive electrode a negative electrode
  • an electrolyte a positive electrode
  • a separator a separator for separating the non-aqueous secondary battery from a positive electrode
  • a negative electrode a negative electrode
  • an electrolyte a positive electrode
  • a separator a separator for separating the non-aqueous secondary battery which concerns on this embodiment.
  • the non-aqueous secondary battery which concerns on this embodiment is either a laminated battery, a laminated square battery, a wound square battery, or a wound cylindrical battery.
  • the positive electrode is composed of a positive electrode active material obtained by mixing at least two positive electrode active materials containing at least the first and second positive electrode active materials described in the preceding section (I), a conductive material, and a binder.
  • a positive electrode active material obtained by mixing at least two positive electrode active materials containing at least the first and second positive electrode active materials described in the preceding section (I), a conductive material, and a binder.
  • it can be produced by a known method such as applying a slurry obtained by mixing a positive electrode active material including the first and second positive electrode active materials, a conductive material, and a binder with an organic solvent or water to a current collector. it can.
  • binder examples include polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, ethylene propylene diene polymer, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluorine rubber, polyvinyl acetate, polymethyl methacrylate, polyethylene. Nitrocellulose or the like can be used.
  • acetylene black carbon, graphite, natural graphite, artificial graphite, needle coke, vapor grown carbon, or the like can be used.
  • foamed (porous) metal having continuous pores, metal formed in a honeycomb shape, sintered metal, expanded metal, non-woven fabric, plate, foil, perforated plate, foil, etc. may be used. it can.
  • N-methylpyrrolidone N-methylpyrrolidone, toluene, cyclohexane, dimethylformamide, dimethylacetamide, methyl ethyl ketone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc. may be used. it can.
  • the mixing ratio of the positive electrode is preferably in the range of 0 to 30 and 0 to 30 for the conductive material and 0 to 30 for the binder when the total of the positive electrode active materials is 100.
  • the thickness of the positive electrode is preferably about 0.01 to 2 mm. If the thickness of the positive electrode is too thick, the conductivity is lowered, and if the thickness is too thin, the capacity per unit area is lowered.
  • the electrode obtained by coating and drying may be consolidated by a roller press or the like in order to increase the packing density of the active material.
  • Negative electrode The negative electrode can be produced by a known method. Specifically, it can be produced in the same manner as described in the method for producing the positive electrode described in the previous section (a). That is, after mixing a known binder and a known conductive material described in the above-described method for producing a positive electrode with a negative electrode active material, the mixed powder is formed into a sheet shape, and the formed body is made of stainless steel, copper, or the like. What is necessary is just to crimp
  • a known material can be used as the negative electrode active material.
  • the potential for lithium insertion and desorption is close to the deposition and dissolution potential for metallic lithium.
  • a typical example is a carbon material such as natural or artificial graphite in the form of particles (scale-like, lump-like, fibrous, whisker-like, spherical, pulverized particles, etc.).
  • artificial graphite examples include graphite obtained by graphitizing mesocarbon microbeads, mesophase pitch powder, isotropic pitch powder, and the like. Also, graphite particles having amorphous carbon attached to the surface can be used. Among these, natural graphite is more preferable because it is inexpensive and close to the redox potential of lithium and can constitute a high energy density battery.
  • lithium transition metal oxides lithium transition metal nitrides, transition metal oxides, metals alloyed with lithium, silicon oxide, and the like can also be used as the negative electrode active material.
  • Li 4 Ti 5 O 12 is more preferable because it has high potential flatness and a small volume change due to charge and discharge.
  • Electrolyte for example, an organic electrolyte, a gel electrolyte, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt, or the like can be used. After the electrolyte is injected, the opening of the battery is sealed. Gas generated by energization before sealing may be removed.
  • organic solvent constituting the organic electrolyte examples include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC) and butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate, and dipropyl carbonate.
  • cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC) and butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate, and dipropyl carbonate.
  • Chain carbonates such as carbonate, lactones such as ⁇ -butyrolactone (GBL) and ⁇ -valerolactone, furans such as tetrahydrofuran and 2-methyltetrahydrofuran, diethyl ether, 1,2-dimethoxyethane, 1,2-di Examples include ethers such as ethoxyethane, ethoxymethoxyethane, and dioxane, dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, and methyl acetate. One or more of these can be used in combination.
  • cyclic carbonates such as PC (propylene carbonate), EC (ethylene carbonate) and butylene carbonate are high-boiling solvents, they are suitable as solvents to be mixed with the GBL.
  • Examples of the electrolyte salt constituting the organic electrolyte include lithium borofluoride (LiBF 4 ), lithium hexafluorophosphate (LiPF 6 ), lithium trifluoromethanesulfonate (LiCF 3 SO 3 ), lithium trifluoroacetate (LiCF 3). COO), lithium salts such as lithium bis (trifluoromethanesulfone) imide (LiN (CF 3 SO 2 ) 2 ), and the like can be used by mixing one or more of these.
  • the salt concentration of the electrolytic solution is preferably 0.5 to 3 mol / L (liter).
  • separator examples include porous materials and nonwoven fabrics.
  • a material for the separator a material that does not dissolve and does not swell in the organic solvent contained in the electrolyte described above is preferable.
  • Specific examples include polyester-based polymers, polyolefin-based polymers (for example, polyethylene and polypropylene), ether-based polymers, and inorganic materials such as glass.
  • various materials used in conventionally known non-aqueous electrolyte secondary batteries can be used for elements such as a separator, a battery case, and other structural materials, and there is no particular limitation.
  • Non-aqueous secondary battery manufacturing method includes, for example, the above-described (b) between the positive electrode described in the previous item (a) and the negative electrode described in the previous item (b). It can be produced by laminating the positive electrode, the negative electrode, and the separator with the separator described in d) interposed therebetween.
  • the stacked positive electrode, negative electrode, and separator may have, for example, a strip-like planar shape. When a cylindrical or flat battery is manufactured, the stacked positive electrode, negative electrode, and separator may be wound up.
  • FIG. 1 shows a wound type secondary battery 10
  • FIG. 2 shows an electrode body 12 provided in the wound type secondary battery 10.
  • the electrode body 12 is configured as a wound body in which a positive electrode 12a, a separator 12c, and a negative electrode 12b are stacked and wound.
  • the electrode body 12 is inserted into a cylindrical battery can 11.
  • a lid 11c having a resin packing (not shown) is fitted into the opening of the battery can 11 forming the battery container to form a container.
  • a method of caulking the battery can 11 is common.
  • a positive electrode terminal 11a is formed on the lid 11c, and the positive electrode terminal 11a is electrically connected to the positive electrode 12a.
  • the end surface of the battery can 11 opposite to the positive electrode terminal 11a forms a negative electrode terminal 11b, and the negative electrode terminal 11b is electrically connected to the negative electrode 12b.
  • FIG. 3 shows a stacked secondary battery 110 as an example of a flat battery.
  • This stacked secondary battery 110 houses an electrode group 113 as a stacked body shown in FIG. 4 in an outer container 111 that is a storage container.
  • a plurality of positive electrodes 113a and a plurality of negative electrodes 113b are alternately stacked so that the separator 113c is sandwiched between the positive electrode 113a and the negative electrode 113b.
  • the plurality of positive electrodes 113 a are electrically connected to the positive electrode current collecting tab 114, and the plurality of negative electrodes 113 b are electrically connected to the negative electrode current collecting tab 115.
  • One of the positive electrode current collecting tab 114 and the negative electrode current collecting tab 115 is electrically connected to one of the two electrode terminals 112 forming a terminal portion formed on the side surface of the outer casing 111. .
  • the other of the positive current collecting tab 114 and the negative current collecting tab 115 is electrically connected to the other of the two electrode terminals 112.
  • the exterior container 111 is sealed to shield the electrodes 113a and 113b and the separator 113c from the outside air.
  • a method of sealing by attaching a lid 111a called a metallic sealing plate to the opening of the box 111b and attaching the lid 111a to the lid 111b by welding can be used.
  • a method for sealing the outer container 111 besides this method, a method of sealing with a binder or a method of fixing with a bolt via a gasket can be used.
  • reference numeral 2b is an electrode terminal electrically connected to the negative electrode 1b
  • reference numeral 2a is an electrode terminal electrically connected to the positive electrode 1a.
  • the positive electrode according to the embodiment of the present invention is provided, and the positive electrode has two or more positive electrode actives having different volume change rates during charge and discharge and having an olivine structure.
  • the positive electrode having two or more positive electrode active materials can reduce the volume change at the time of charging / discharging with the positive electrode active material having a smaller volume change rate, and can reduce the stress inside the electrode. Therefore, it is possible to make it difficult for the conductive path between the positive electrode active material and the conductive material to break, to suppress an increase in electric resistance at the positive electrode, and to suppress a decrease in electric capacity.
  • an electrode prepared by applying two or more positive electrode active materials having different volume change rates onto a metal foil such as an aluminum foil has a relatively high volume change rate.
  • the volume change of the positive electrode active material during charge / discharge can be reduced while suppressing a decrease in theoretical capacity. Therefore, since the change in the thickness of the electrode during charging / discharging can be reduced, the change in the thickness of the battery accompanying charging / discharging is reduced, and in a battery using metal for the exterior, the stress to the exterior is reduced. As a result, a highly reliable battery can be provided.
  • the battery using the positive electrode according to the embodiment of the present invention since the battery using the positive electrode according to the embodiment of the present invention has excellent long-term reliability, it is possible to store the power of solar cells used for a long period of time, the storage of midnight power, the natural power such as wind power, geothermal power, and wave power. Suitable for energy storage. These batteries can be used as a module in a state where a plurality of these batteries are connected.
  • the positive electrode and non-aqueous secondary battery of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope indicated in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.
  • the positive electrode of the above embodiment includes lithium iron phosphate (LiFePO 4 ) as the first positive electrode active material
  • the second positive electrode active material is represented by the general formula (2) or the general formula (3).
  • the first positive electrode active material and the second positive electrode active material are both active materials represented by the general formula (2) or the general formula (3)
  • the second positive electrode active material is the second active material.
  • the general formula (2) of the first and second positive electrode active materials is set so that the volume change rate during charge / discharge of the positive electrode active material is smaller than the volume change rate during charge / discharge of the first positive electrode active material.
  • (3) x, y, z and A and M may be set.
  • the positive electrode is a positive electrode having different volume change rates of three or more selected from two or more active materials represented by the general formula (2) or the general formula (3) and lithium iron phosphate. It may be provided with an active material.
  • LiFeZrPSiO 4 Li (OC 2 H 5 ) as a lithium source, Fe (CH 3 COO) 2 as an iron source, Zr (OC 2 H 5 ) 4 as a zirconium source, (NH 4 ) 2 HPO 4 as a phosphorus source, silicon source As a sample, Si (OC 2 H 5 ) 4 was weighed so as to have a predetermined molar ratio.
  • the Li source, the Zr source, and the Si source were dissolved in 20 g of butanol. Further, the Fe source and the P source were dissolved in 4 times the number of moles of water with respect to the total number of moles of metal alkoxide (Fe source, Si source and Li source). Butanol in which a metal alkoxide was dissolved, Fe source, and water in which a P source was dissolved were mixed, stirred for 1 hour, and then dried in a dryer at 60 ° C. as a precursor.
  • the obtained amorphous precursor was baked at 600 ° C. for 12 hours in a nitrogen atmosphere to obtain an olivine-type positive electrode active material.
  • the four samples having different composition ratios of Fe, Zr, P, and Si synthesized in this way are designated as A2, A3, A4, and A5.
  • a positive electrode active material having the same composition as the Li desorption state whose charge capacity was confirmed was used as the positive electrode active material after Li desorption at room temperature.
  • X-ray measurement was performed. Specifically, a battery is manufactured by a battery manufacturing method described later, the positive electrode is taken out in a fully charged state, the electrode is washed with an organic solvent, and then the positive electrode active material XRD (X (Line diffraction) measurements were performed.
  • volume change rate V (%) due to charging / discharging of the LiFePO 4 positive electrode active material is determined from the structure constant during charging and the structure constant during discharging from the lattice constant of the structure during charging and the lattice constant of the structure during discharging.
  • the volume V2 was determined and determined by the following formula (4).
  • Volume change rate V (%) (1 ⁇ V1 / V2) ⁇ 100 (4)
  • the structure at the time of charging was a structure at the time of Li desorption
  • the structure at the time of discharging was an initial structure at the time of synthesis.
  • Table 1 in FIG. 6 shows the composition and volume change rate of the positive electrode active materials A1 to A5.
  • the positive electrode active material A1 was LiFePO 4 , and the volume change rate was 6.6%.
  • the positive electrode active material A2 was LiFe 0.95 Zr 0.05 P 0.9 Si 0.1 O 4 and the volume change rate was 6.0%.
  • the positive electrode active material A3 was LiFe 0.925 Zr 0.075 P 0.85 Si 0.15 O 4 and the volume change rate was 5.4%.
  • the positive electrode active material A4 was LiFe 0.9 Zr 0.1 P 0.8 Si 0.2 O 4 and the volume change rate was 4.6%.
  • the positive electrode active material A5 was LiFe 0.875 Zr 0.125 P 0.75 Si 0.25 O 4 and the volume change rate was 3.6%.
  • the positive electrode active material, acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.), CMC (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and aqueous binder (manufactured by JSR) are mixed in a mass ratio of 100: 4: 1.2: 6.
  • the mixture was mixed with water to form a slurry, and applied to an aluminum foil having a thickness of 20 ⁇ m so as to have a thickness of 100 ⁇ m to 200 ⁇ m to obtain a positive electrode.
  • the electrode size of the positive electrode was 2.8 cm ⁇ 2.8 cm.
  • Natural graphite powder was used as the negative electrode active material. About 10% by mass of polyvinylidene fluoride resin powder was mixed with this negative electrode active material as a binder. This mixture was dissolved in N-methyl-2-pyrrolidone to form a slurry, which was applied to both sides of a copper foil having a thickness of 20 micrometers, dried, and then pressed to produce a negative electrode.
  • Example 2 The same procedure as in Example 1 was performed except that 70% by mass of the positive electrode active material of A1 and 30% by mass of the positive electrode active material of A2 were mixed. The battery of Example 2 was produced.
  • Example 3 Implementation was performed in the same manner as in Example 1 except that a mixture of 50% by mass of the positive electrode active material of A1 and 50% by mass of the positive electrode active material of A2 was used as the positive electrode active material.
  • the battery of Example 3 was produced.
  • Example 4 The same procedure as in Example 1 was performed except that a mixture of 90% by mass of the positive electrode active material of A1 and 10% by mass of the positive electrode active material of A3 was used as the positive electrode active material. The battery of Example 4 was produced.
  • Example 5 (Example 5) Implementation was performed in the same manner as in Example 1 except that a mixture of 70% by mass of the positive electrode active material of A1 and 30% by mass of the positive electrode active material of A3 was used as the positive electrode active material. The battery of Example 5 was produced.
  • Example 6 The same procedure as in Example 1 was performed except that 50% by mass of the positive electrode active material of A1 and 50% by mass of the positive electrode active material of A3 were used as the positive electrode active material. The battery of Example 6 was produced.
  • Example 7 The same procedure as in Example 1 was performed except that a mixture of 90% by mass of the positive electrode active material of A1 and 10% by mass of the positive electrode active material of A4 was used as the positive electrode active material. The battery of Example 7 was produced.
  • Example 8 The same procedure as in Example 1 was performed except that 70% by mass of the positive electrode active material of A1 and 30% by mass of the positive electrode active material of A4 were used as the positive electrode active material. The battery of Example 8 was produced.
  • Example 9 The same procedure as in Example 1 was performed except that 50% by mass of the positive electrode active material of A1 and 50% by mass of the positive electrode active material of A4 were used as the positive electrode active material. The battery of Example 9 was produced.
  • Example 10 The same procedure as in Example 1 was performed except that a mixture of 90% by mass of the positive electrode active material of A1 and 10% by mass of the positive electrode active material of A5 was used as the positive electrode active material. The battery of Example 10 was produced.
  • Example 11 The same procedure as in Example 1 was performed except that 70% by mass of the positive electrode active material of A1 and 30% by mass of the positive electrode active material of A5 were used as the positive electrode active material. The battery of Example 11 was produced.
  • Example 12 Implementation was performed in the same manner as in Example 1 except that a mixture of 50% by mass of the positive electrode active material of A1 and 50% by mass of the positive electrode active material of A5 was used as the positive electrode active material.
  • the battery of Example 12 was produced.
  • Comparative Example 1 A battery of Comparative Example 1 was produced in the same manner as in Example 1 except that 100% by mass of the positive electrode active material of A1 was used as the positive electrode active material.
  • Comparative Example 2 A battery of Comparative Example 2 was produced in the same manner as in Example 1 except that 100% by mass of the positive electrode active material of A2 was used as the positive electrode active material.
  • Comparative Example 3 A battery of Comparative Example 3 was produced in the same manner as in Example 1 except that 100% by mass of the positive electrode active material of A3 was used as the positive electrode active material.
  • Comparative Example 4 A battery of Comparative Example 4 was produced in the same manner as in Example 1 except that 100% by mass of the positive electrode active material of A4 was used as the positive electrode active material.
  • Comparative Example 5 A battery of Comparative Example 5 was produced in the same manner as in Example 1 except that 100% by mass of the positive electrode active material of A5 was used as the positive electrode active material.
  • a laminate produced by sandwiching a porous polyethylene separator 1c between the positive electrode 1a and the negative electrode 1b described above is formed of two metal foils. It was sandwiched between laminate films 3 each having a thermoplastic resin affixed thereto, and the periphery was sealed by heat welding to provide a battery exterior.
  • reference numeral 2b is an electrode terminal electrically connected to the negative electrode 1b
  • reference numeral 2a is an electrode terminal electrically connected to the positive electrode 1a.
  • the laminate film 3 is provided with an opening (not shown) for electrolyte injection.
  • the opening was impregnated with 30% by volume of ethylene carbonate and 70% by volume of diethyl carbonate dissolved in 1 mol / liter of LiPF 6 as an electrolyte.
  • the electrolyte injection opening of the battery container is sealed to complete the production of the secondary battery.
  • the capacity retention rate of (12.52 / 19.87) was 63.0%.
  • the capacity retention ratio of (12.50 / 19.23) was 65.0%.
  • the capacity retention rate of (12.41 / 20.02) was 62.0%.
  • the capacity retention rate of (12.44 / 19.13) was 65.0%.
  • the capacity retention rate of (12.37 / 19.42) was 63.5%.
  • the capacity retention rate of (12.74 / 18.55) was 68.7%.
  • the capacity retention ratio of (12.37 / 17.33) was 71.4%.
  • the capacity retention rate of (12.21 / 19.09) was 64.0%.
  • the capacity retention rate of (12.36 / 17.47) was 70.7%.
  • Example 12 having the largest mass% of the positive electrode active material A5 having the smallest volume change rate among the positive electrode active materials A1 to A5 has the largest capacity retention ratio at the 1000th time. It became.
  • Example 12 the initial capacity was the smallest value among Examples 1 to 12.
  • Comparative Example 5 in which the mass% of the positive electrode active material A5 having the smallest volume change rate among the positive electrode active materials A1 to A5 is 100%, the capacity retention rate at the 1000th time is that of Examples 1 to 12, although it was the largest among Comparative Examples 1-5, the initial capacity of Comparative Example 5 was the smallest among Examples 1-12 and Comparative Examples 1-5. For this reason, the 1000th capacity of Comparative Example 5 was smaller than that of any of Examples 1-12. Further, in any of the comparative examples 1 to 5, the 1000th capacity is The value was smaller than the 1000th capacity of Examples 1-12.
  • M is an active material represented as Zr, but the second positive electrode active material may be another active material represented by the general formula (2).
  • the second positive electrode active material may be an active material represented by the general formula (3).
  • the first positive electrode active material was lithium iron phosphate (LiFePO 4), both of the first positive electrode active material first cathode active material and second cathode active material,
  • the volume change rate during charge / discharge of the second positive electrode active material is the volume change during charge / discharge of the first positive electrode active material, which is the active material represented by the general formula (2) or the general formula (3).
  • the values of x, y, z and A and M in the general formula (2) or (3) of the first and second positive electrode active materials may be set so as to be smaller than the rate.
  • the positive electrode is a positive electrode having different volume change rates of three or more selected from two or more active materials represented by the general formula (2) or the general formula (3) and lithium iron phosphate. It may be provided with an active material.
  • the positive electrode (1a, 12a, 113a) of the present invention two or more positive electrode active materials having different volume change rates during charge and discharge are provided, and the two or more positive electrode active materials have an olivine structure.
  • the volume change of the positive electrode active material at the time of charging / discharging can be made small. Therefore, while using a positive electrode active material having an olivine structure that is superior in terms of safety and cost, the stress inside the electrode is relieved, and the conductive path between the positive electrode active material and the conductive material is less likely to break down. Reduction can be suppressed and a long life can be realized.
  • the volume change rate at the time of charge / discharge of at least one positive electrode active material of the two or more positive electrode active materials is lithium iron phosphate. It is smaller than the volume change rate during charging and discharging.
  • the volume change of the electrode accompanying charging / discharging is reduced, the stress applied to the inside of the electrode is reduced, and charging / discharging Deterioration can be suppressed.
  • one of the two or more positive electrode active materials is lithium iron phosphate.
  • having a positive electrode active material made of lithium iron phosphate is particularly excellent in terms of safety and cost.
  • the mass of the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate is 30% or more with respect to the mass of the total positive electrode active material.
  • the capacity retention after charging / discharging can be particularly improved.
  • the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate has an olivine structure and has a general formula (Li 1-x AxFe 1-y MyP 1-z Si z O 4 )
  • A is at least one of Na, Fe, and M
  • M is any of Ti, V, Nb, Al, Y, Zr, and Sn
  • x Is 0 ⁇ x ⁇ 0.25
  • y is 0 ⁇ y ⁇ 0.25
  • z is 0 ⁇ z ⁇ 0.25.
  • the positive electrode active material is charged and discharged at the same potential as lithium iron phosphate, even when the lithium iron phosphate and the positive electrode active material are mixed and used, the potential is The battery can be used without worrying about changes.
  • the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate has a volume change rate of 6.0% or less.
  • the capacity retention after charging / discharging can be particularly improved.
  • the mass of the positive electrode active material having a volume change rate smaller than the volume change rate during charging and discharging of the lithium iron phosphate is 30% or more with respect to the mass of the total positive electrode active material, and the iron phosphate
  • the positive electrode active material having a volume change rate smaller than the volume change rate during lithium charge / discharge has a volume change rate of 6.0% or less.
  • the significance of the 30% value and the 6.0% value will be described.
  • the horizontal axis is the average volume change rate calculated from the ratio of the active material, and the vertical axis is the capacity after 1000 cy
  • the average volume change is around 6%. It has become.
  • at least one of the volume changes needs to be 6% or less, and the mixing amount needs about 30%.
  • the nonaqueous secondary battery of the present invention includes the positive electrode.
  • the positive electrode having two or more positive electrode active materials having an olivine structure and different volume change rates at the time of charge / discharge can be used to change the volume of the positive electrode active material during the charge / discharge. Since it can be made small, the change of the thickness of the electrode at the time of charging / discharging can be decreased, and a highly reliable battery can be provided.
  • the positive electrode of the present invention is not only excellent in safety and cost, but can provide a battery having a long life. Therefore, the positive electrode of the present invention can be suitably used as a positive electrode in a non-aqueous secondary battery such as a lithium ion battery.

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Abstract

Cette invention concerne une cathode (12a) comprenant au moins deux matériaux actifs de cathode présentant des taux différents de changement de volume pendant la charge/décharge et présentant une structure olivine. Ladite cathode assure une haute capacité de charge/décharge ainsi qu'une charge/décharge à un potentiel électrique prédéterminé tandis qu'elle permet de supprimer le délaminage du film de l'électrode en supprimant les changements de volume des matériaux actifs de cathode à un niveau bas pendant la charge/décharge du fait que le matériau actif d'électrode présente le taux de changement de volume le plus faible.
PCT/JP2013/079213 2012-11-14 2013-10-29 Cathode et élément rechargeable non aqueux WO2014077118A1 (fr)

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JP2012250359A JP2016015197A (ja) 2012-11-14 2012-11-14 正極および非水系二次電池

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006523368A (ja) * 2003-04-03 2006-10-12 ヴァレンス　テクノロジー　インコーポレーテッド 混合粒子を含む電極
JP2011018547A (ja) * 2009-07-08 2011-01-27 Toyota Motor Corp リチウムイオン二次電池、及び、電池システム
JP2011517361A (ja) * 2007-07-12 2011-06-02 エイ １２３ システムズ，インク． リチウムイオンバッテリー用の多機能合金オリビン
JP2011253631A (ja) * 2010-05-31 2011-12-15 Sharp Corp 正極活物質、正極及び非水電解質二次電池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006523368A (ja) * 2003-04-03 2006-10-12 ヴァレンス　テクノロジー　インコーポレーテッド 混合粒子を含む電極
JP2011517361A (ja) * 2007-07-12 2011-06-02 エイ １２３ システムズ，インク． リチウムイオンバッテリー用の多機能合金オリビン
JP2011018547A (ja) * 2009-07-08 2011-01-27 Toyota Motor Corp リチウムイオン二次電池、及び、電池システム
JP2011253631A (ja) * 2010-05-31 2011-12-15 Sharp Corp 正極活物質、正極及び非水電解質二次電池

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