WO2018021480A1 - Substance active d'électrode positive pour batteries secondaires au lithium-ion, électrode positive pour batteries secondaires au lithium-ion, et batterie secondaire au lithium-ion l'utilisant - Google Patents

Substance active d'électrode positive pour batteries secondaires au lithium-ion, électrode positive pour batteries secondaires au lithium-ion, et batterie secondaire au lithium-ion l'utilisant Download PDF

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WO2018021480A1
WO2018021480A1 PCT/JP2017/027262 JP2017027262W WO2018021480A1 WO 2018021480 A1 WO2018021480 A1 WO 2018021480A1 JP 2017027262 W JP2017027262 W JP 2017027262W WO 2018021480 A1 WO2018021480 A1 WO 2018021480A1
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Prior art keywords
positive electrode
active material
ion secondary
lithium ion
carbon particles
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PCT/JP2017/027262
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English (en)
Japanese (ja)
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淳平 下羽
佳太郎 大槻
秀明 関
貞村　英昭
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Tdk株式会社
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Priority claimed from JP2016147478A external-priority patent/JP2019164880A/ja
Priority claimed from JP2016147479A external-priority patent/JP2019164881A/ja
Application filed by Tdk株式会社 filed Critical Tdk株式会社
Publication of WO2018021480A1 publication Critical patent/WO2018021480A1/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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • 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 active material for lithium ion secondary batteries having high rate characteristics, a positive electrode for lithium ion secondary batteries, and a lithium ion secondary battery using the same.
  • lithium ion secondary batteries have been widely used as power sources for portable electronic devices, automobiles, and power storage.
  • the lithium ion secondary battery is mainly composed of a positive electrode, a negative electrode, a separator that insulates the positive electrode from the negative electrode, and an electrolyte that enables ions to move between the positive electrode and the negative electrode. Since lithium ion secondary batteries have high energy density, they have been put into practical use as power sources for portable electronic devices such as mobile phones and notebook computers, and are widely used.
  • portable electronic devices, communication devices, and the like there is a strong demand for lithium ion secondary batteries with higher energy density from the viewpoints of downsizing and weight reduction of devices. Further, there is a strong demand for extending the life of automobile batteries.
  • lithium cobaltate LiCoO 2
  • lithium nickelate LiNiO 2
  • lithium nickel oxide in which a part of lithium nickelate is substituted with Co, Mn, Al, etc.
  • a compound having a layered rock salt structure such as a complex oxide is used.
  • LiFePO 4 lithium iron phosphate
  • Patent Document 1 reports that rate characteristics are improved by supporting LiVOPO 4 whose particle surface is coated with carbon on carbon particles.
  • Patent Document 2 reports that the rate characteristic is improved by forming a carbon coating layer on at least a part of the particle surface of LiVOPO 4 .
  • Patent Document 3 reports that rate characteristics are improved by supporting a plurality of hemispherical carbon particles on the surface of LiVOPO 4 particles.
  • Japanese Unexamined Patent Publication No. 2010-86777 A) Japanese Unexamined Patent Publication No. 2008-277119 (A) Japanese Unexamined Patent Publication No. 2010-218830 (A)
  • the present invention has been made in view of the above-described problems of the prior art, and has a positive electrode active material for a lithium ion secondary battery having high rate characteristics, a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery using the same.
  • the purpose is to provide.
  • a positive electrode active material for a lithium ion secondary battery which is one embodiment of the present invention has the following configuration.
  • (1) having active material particles mainly composed of lithium vanadium phosphate represented by the following composition formula (1), and a carbon material that expands two-dimensionally,
  • the carbon material is a coating layer containing at least a part of plate-like carbon particles or graphene and covering at least a part of the surface of the active material particles. material.
  • Li a (M) b (PO 4 ) c (1) (M is VO or V, and 0.05 ⁇ a ⁇ 3.3, 0.9 ⁇ b ⁇ 2.2, and 0.9 ⁇ c ⁇ 3.3.)
  • M is VO or V
  • the positive electrode active material for a lithium ion secondary battery includes the above-described two-dimensionally expanded carbon material, which improves the electron conductivity on the surface of the active material particles mainly composed of lithium vanadium phosphate. It is estimated that.
  • the positive electrode active material for a lithium ion secondary battery according to (1) wherein the two-dimensionally expanding carbon material is at least partly plate-like carbon particles.
  • rate characteristics are improved. This is because the active material particles containing lithium vanadium phosphate as the main component and the plate-like carbon particles are used, and the lithium vanadium phosphate is efficiently used as compared with the case where a conventional conductive additive is used. It is presumed that the electron conductivity is greatly improved by reducing the charge transfer resistance on the surface of the active material particles as a component.
  • the ratio (A / B) of the average thickness B to the average plate surface diameter A in the carbon particles is 5 ⁇ A / B ⁇ 1000, according to any one of (2) to (4),
  • the positive electrode active material for lithium ion secondary batteries as described.
  • At least a part of the carbon particles covers at least a part of the surface of the active material particles mainly composed of the lithium vanadium phosphate.
  • the positive electrode active material for lithium ion secondary batteries as described in any one. Thereby, it is estimated that the adhesion between the active material particles mainly composed of carbon particles and lithium vanadium phosphate is improved and the effect of reducing the charge transfer resistance is obtained.
  • At least a part of the carbon particles is complexed with active material particles mainly composed of the lithium vanadium phosphate, according to any one of (2) to (6), The positive electrode active material for lithium ion secondary batteries as described.
  • the plate carbon particles are contained in an amount of 0.1 to 8% by weight with respect to the active material particles mainly composed of lithium vanadium phosphate.
  • the positive electrode active material for lithium ion secondary batteries as described in any one of 7). By setting it as the said range, it is estimated that the charge transfer resistance in the surface of the active material particle which has lithium vanadium phosphate as a main component is reduced more efficiently.
  • Positive electrode active material By using the positive electrode active material for a lithium ion secondary battery, a lithium ion secondary battery with improved rate characteristics can be provided. This is presumably because the electron conductivity is improved by the graphene contained in the coating layer. In particular, when the coating layer is formed using a mechanochemical method, the rate characteristics are greatly improved. This is presumed to be because graphene contained in the coating layer is oriented in the horizontal direction to the coating layer, so that the in-plane direction of graphene with excellent electron conductivity matches the direction of electron conduction in the positive electrode.
  • the single layer graphene flexibly follows the active material, and when it contains multi-layer graphene, it has better electronic conductivity, so that the rate characteristics are improved.
  • a positive electrode for a lithium ion secondary battery comprising the positive electrode active material for a lithium ion secondary battery according to any one of (1) to (10).
  • a positive electrode active material for a lithium ion secondary battery a positive electrode for a lithium ion secondary battery, and a lithium ion secondary battery using the same, having high rate characteristics.
  • first and second embodiments of the present invention will be described.
  • this invention is not limited to the following embodiment.
  • the constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.
  • the dimensional ratio of drawing is not restricted to the ratio of illustration.
  • the first embodiment at least a part of plate-like carbon particles is used as a carbon material that expands two-dimensionally.
  • a coating layer that contains graphene and covers at least a part of the surface of the active material particles is used as a carbon material that expands two-dimensionally.
  • the lithium ion secondary battery 100 mainly includes a laminate 40, a case 50 that accommodates the laminate 40 in a sealed state, and a pair of leads 60 and 62 connected to the laminate 40. Although not shown, the electrolytic solution is housed in the case 50 together with the laminate 40.
  • the laminated body 40 is configured such that the positive electrode 20 and the negative electrode 30 are arranged to face each other with the separator 10 interposed therebetween.
  • the positive electrode 20 is obtained by providing a positive electrode active material layer 24 on a plate-like (film-like) positive electrode current collector 22.
  • the negative electrode 30 is obtained by providing a negative electrode active material layer 34 on a plate-like (film-like) negative electrode current collector 32.
  • the positive electrode active material layer 24 and the negative electrode active material layer 34 are in contact with both sides of the separator 10.
  • Leads 62 and 60 are connected to the ends of the positive electrode current collector 22 and the negative electrode current collector 32, respectively, and the ends of the leads 60 and 62 extend to the outside of the case 50.
  • the positive electrode 20 and the negative electrode 30 are collectively referred to as electrodes 20 and 30, and the positive electrode current collector 22 and the negative electrode current collector 32 are collectively referred to as current collectors 22 and 33, the positive electrode active material layer 24 and the negative electrode active material.
  • the material layer 34 is collectively referred to as the active material layers 24 and 34.
  • the positive electrode active material for a lithium ion secondary battery according to this embodiment includes active material particles mainly composed of lithium vanadium phosphate represented by the following composition formula (1), and carbon particles. At least a portion is plate-shaped.
  • Li a (M) b (PO 4 ) c (1) M is VO or V, and 0.05 ⁇ a ⁇ 3.3, 0.9 ⁇ b ⁇ 2.2, and 0.9 ⁇ c ⁇ 3.3.
  • the lithium vanadium phosphate represented by the composition formula (1) does not need to have the stoichiometric oxygen amount represented by this composition formula, and includes a wide range of oxygen-deficient ones. In other words, those identified as the same composition system by X-ray diffraction or the like are targeted.
  • a part of vanadium is selected from the group consisting of W, Mo, Ti, Al, Ni, Co, Mn, Fe, Zr, Cu, Zn, and Yb. It may be substituted with one or more elements.
  • part of phosphorus may be substituted with one or more elements selected from the group consisting of W, Si, S, B, and Mo. .
  • the average particle diameter of the lithium vanadium phosphate according to the present embodiment is preferably 50 nm to 1000 nm.
  • the average particle diameter is 50 nm or more, lithium vanadium phosphate in the electron movement path is efficiently in contact with the plate-like carbon particles, so that the electron conductivity is improved and the rate characteristics are improved.
  • the average particle diameter is 500 nm or less, the path through which electrons move inside the crystal of lithium vanadium phosphate having a low electron conductivity is shortened, thereby improving rate characteristics.
  • the lithium vanadium phosphate is preferably primary particles or flat secondary particles. By being primary particles or flat secondary particles, the path through which electrons move inside the crystal of lithium vanadium phosphate is shortened, and the rate characteristics are improved.
  • lithium vanadium phosphates represented by the composition formula (1) it is preferable to use a compound represented by LiVOPO 4 or Li 3 V 2 (PO 4 ) 3 , and it is particularly preferable to use LiVPO 4 .
  • the LiVOPO 4 can have a plurality of crystal phases such as ⁇ -type (triclinic), ⁇ -type (orthorhombic), and ⁇ -type (tetragonal), and in particular has a ⁇ -type (orthogonal) crystal phase. It is preferable. As a result, a higher charge / discharge capacity can be obtained as compared with the case of having an ⁇ -type (triclinic) or ⁇ -type (tetragonal) crystal phase.
  • the lithium vanadium phosphate in the present embodiment may be used by mixing two or more kinds selected from LiVOPO 4 and Li 3 V 2 (PO 4 ) 2 each having ⁇ -type, ⁇ -type, and ⁇ -type crystal phases. Good.
  • the lithium vanadium phosphate according to this embodiment particularly preferably contains 80% or more of LiVOPO 4 having a ⁇ -type crystal phase.
  • the composition and crystal phase of lithium vanadium phosphate contained in the positive electrode active material according to this embodiment can be identified by X-ray diffraction or the like.
  • the content ratio of the active material particles mainly composed of lithium vanadium phosphate contained in the positive electrode active material according to the present embodiment is 50 to 100% by mass, preferably 80 to 100% by mass, more preferably 95 to 100% by mass. %.
  • the carbon particles according to this embodiment are plate-shaped.
  • a carbon particle having a plate shape means that a plurality of carbon particles are formed into a plate shape.
  • the preferred density of the carbon particles formed into a plate shape is 1.0 to 2.2 g / cm 3 . More preferably, it is 1.2 to 2.0 g / cm 3 . Even more preferably, it is 1.5 to 1.8 g / cm 3 .
  • the content ratio of at least partly plate-like carbon particles contained in the positive electrode active material according to the present embodiment is 2 to 20% by mass, preferably 5 to 15% by mass, more preferably 7 to 10% by mass. .
  • the carbon particles according to the present embodiment preferably have an average plate surface diameter A of 50 ⁇ A ⁇ 10000 nm. More preferably, 100 ⁇ A ⁇ 1000 nm.
  • the plate surface diameter is defined as the longest straight line in the surface direction that can be drawn on the plate within the plate made of carbon particles.
  • the average plate surface diameter A is an average value of the measured plate surface diameter values for a plate made of a certain number of carbon particles.
  • the average aspect ratio of the plate made of carbon particles according to this embodiment is 1.0 to 50. More preferably, it is 1.5 to 35. Even more preferably, it is 2.0-21.
  • the aspect ratio can be obtained from the major axis / minor axis, with the plate surface diameter as the major axis and the plate diameter perpendicular to the plate surface diameter as the minor axis.
  • the average aspect ratio is an average value of measured aspect ratio values for a plate made of a certain number of carbon particles.
  • the carbon particles according to the present embodiment preferably have an average thickness B of 0.3 ⁇ B ⁇ 50 nm. More preferably, 3 nm ⁇ B ⁇ 20 nm.
  • the ratio A / B of the average thickness B to the average plate surface diameter A in the carbon particles according to the present embodiment is preferably 5 ⁇ A / B ⁇ 1000. More preferably, 10 ⁇ A / B ⁇ 500.
  • At least a part of the carbon particles according to the present embodiment covers at least a part of the surface of the active material particles mainly composed of lithium vanadium phosphate.
  • the carbon particles according to the present embodiment preferably cover 30% or more of the surface of the active material particles mainly composed of lithium vanadium phosphate. Further, it is more preferable to cover 50% or more of the surface of the active material particles mainly composed of lithium vanadium phosphate, and it is more preferable to cover the whole.
  • the carbon particles is combined with active material particles mainly composed of lithium vanadium phosphate.
  • the plate-like carbon particles covers at least a part of the surface of the active material particles mainly composed of lithium vanadium phosphate, and More preferably, at least a part of the plate-like carbon particles is combined with active material particles mainly composed of lithium vanadium phosphate.
  • the charge transfer resistance as the whole positive electrode active material for the lithium ion secondary battery is combined. By being reduced, it is estimated that a higher rate characteristic is exhibited.
  • carbon particles according to the present embodiment carbon particles having a plate shape manufactured using a method described later can be used. Moreover, the carbon particle which has the existing plate shape can also be used, and these may be mixed and used.
  • conventionally known carbon materials such as a granular shape and a lump shape may be mixed.
  • plate-like carbon particles are included as a main component.
  • 60% by volume or more of the entire carbon material is preferably carbon particles having a plate shape.
  • a more preferable plate-like carbon particle content is 70% by volume or more.
  • An even more preferable plate-like carbon particle content is 80% by volume or more.
  • the carbon particles according to the present embodiment can be observed using a transmission electron microscope (TEM).
  • TEM transmission electron microscope
  • the carbon particles having a plate shape contained in the electrode can be observed and measured with a scanning electron microscope, a transmission electron microscope, or the like after the cross section of the positive electrode is polished with a cross section polisher or an ion milling device.
  • a transmission electron microscope is particularly preferable.
  • the average plate surface diameter A and average thickness B of the carbon particles are selected randomly from 10 plate-like carbon particles, and the average values are defined as the average plate surface diameter A and average thickness B of the carbon particles in the present embodiment.
  • the value can be used to calculate the A / B value.
  • the carbon particles according to the present embodiment are preferably contained at a ratio of 0.1 to 20% by weight with respect to the active material particles mainly composed of lithium vanadium phosphate. More preferably, it is 0.5 to 15% by mass. Even more preferably, it is 5.0 to 12.0% by mass.
  • the carbon particles contained in the positive electrode for a lithium ion secondary battery according to this embodiment can be measured using a carbon / sulfur analyzer or the like.
  • the positive electrode current collector 22 may be a conductive plate material, and for example, a thin metal plate of aluminum, copper, or nickel foil can be used.
  • the binder binds the active materials to each other and binds the active material to the current collector 22.
  • the binder is not particularly limited as long as it can be bonded as described above.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • FEP tetrafluoroethylene-hexafluoropropylene copolymer
  • PFA tetrafluoroethylene- Perfluoroalkyl vinyl ether copolymer
  • ETFE ethylene-tetrafluoroethylene copolymer
  • PCTFE polychlorotrifluoroethylene
  • ECTFE ethylene-chlorotrifluoroethylene copolymer
  • PVF polyvinyl fluoride
  • binder for example, vinylidene fluoride-hexafluoropropylene-based fluorororubber (VDF-HFP-based fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene-based fluororubber (VDF-HFPPTFE-based) Fluorine rubber), vinylidene fluoride-pentafluoropropylene fluorine rubber (VDF-PFP fluorine rubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluorine rubber (VDF-PFP-TFE fluorine rubber), vinylidene fluoride Ride-perfluoromethyl vinyl ether-tetrafluoroethylene fluoro rubber (VDF-PFMVE-TFE fluoro rubber), vinylidene fluoride-chlorotrifluoroethylene fluoro rubber The containing rubbers (VDF-CTFE-based fluorine
  • an electron conductive conductive polymer or an ion conductive conductive polymer may be used as the binder.
  • the electron conductive conductive polymer include polyacetylene.
  • the binder since the binder also functions as a conductive material, it is not necessary to add a conductive material.
  • the ion conductive conductive polymer include those obtained by combining a polymer compound such as polyethylene oxide and polypropylene oxide with a lithium salt or an alkali metal salt mainly composed of lithium.
  • the negative electrode active material should just be a compound which can occlude / release lithium ion, and can use the well-known negative electrode active material for lithium ion batteries.
  • the negative electrode active material include carbon materials that can occlude and release lithium ions (natural graphite, artificial graphite), carbon nanotubes, non-graphitizable carbon, graphitizable carbon, low-temperature calcined carbon, and the like, aluminum, silicon And particles containing a metal that can be combined with lithium such as tin, an amorphous compound mainly composed of an oxide such as silicon dioxide and tin dioxide, and lithium titanate (Li 4 Ti 5 O 12 ). . It is preferable to use graphite having a high capacity per unit weight and relatively stable.
  • the negative electrode current collector 32 may be a conductive plate material, and for example, a thin metal plate of aluminum, copper, or nickel foil can be used.
  • the conductive material examples include carbon powder such as carbon black, carbon nanotube, carbon material, fine metal powder such as copper, nickel, stainless steel and iron, a mixture of carbon material and fine metal powder, and conductive oxide such as ITO. It is done.
  • the binder used for a negative electrode can use the same thing as a positive electrode.
  • the separator 18 only needs to be formed of an electrically insulating porous structure, for example, a single layer of a film made of polyethylene, polypropylene or polyolefin, a stretched film of a laminate or a mixture of the above resins, or cellulose, polyester and Examples thereof include a fiber nonwoven fabric made of at least one constituent material selected from the group consisting of polypropylene.
  • Non-aqueous electrolyte The nonaqueous electrolytic solution has an electrolyte dissolved in a nonaqueous solvent, and may contain a cyclic carbonate and a chain carbonate as a nonaqueous solvent.
  • the cyclic carbonate is not particularly limited as long as it can solvate the electrolyte, and a known cyclic carbonate can be used.
  • a known cyclic carbonate can be used.
  • ethylene carbonate, propylene carbonate, butylene carbonate, and the like can be used.
  • the chain carbonate is not particularly limited as long as it can reduce the viscosity of the cyclic carbonate, and a known chain carbonate can be used. Examples thereof include diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. In addition, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, ⁇ -butyrolactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, and the like may be mixed.
  • the ratio of the cyclic carbonate and the chain carbonate in the non-aqueous solvent is preferably 1: 9 to 1: 1 by volume.
  • Examples of the electrolyte include LiPF 6 , LiClO 4 , LiBF 4 , LiCF 3 SO 3 , LiCF 3 , CF 2 SO 3 , LiC (CF 3 SO 2 ) 3 , LiN (CF 3 SO 2 ) 2 , LiN (CF 3 Lithium salts such as CF 2 SO 2 ) 2 , LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiN (CF 3 CF 2 CO) 2 , LiBOB can be used.
  • these lithium salts may be used individually by 1 type, and may use 2 or more types together.
  • LiPF 6 is preferably included from the viewpoint of conductivity.
  • the concentration of the electrolyte in the non-aqueous electrolyte is preferably adjusted to 0.5 to 2.0 mol / L.
  • the concentration of the electrolyte is 0.5 mol / L or more, the conductivity of the nonaqueous electrolytic solution can be sufficiently secured, and a sufficient capacity can be easily obtained during charging and discharging.
  • the electrolyte concentration is suppressed to within 2.0 mol / L, it is possible to suppress an increase in the viscosity of the non-aqueous electrolyte, to sufficiently secure the mobility of lithium ions, and to obtain a sufficient capacity during charging and discharging. It becomes easy.
  • the lithium ion concentration in the non-aqueous electrolyte is preferably adjusted to 0.5 to 2.0 mol / L, and the lithium ion concentration from LiPF 6 is 50 mol%. More preferably, it is contained.
  • the positive electrode active material according to the present embodiment can be synthesized using hydrothermal synthesis, and includes a precursor synthesis step and a heat treatment step.
  • a precursor synthesis process a lithium source.
  • the mixture containing the phosphate source, vanadium source, reducing agent and water is dried in its entirety. Thereby, a precursor is obtained.
  • the obtained precursor is heat treated.
  • Precursor synthesis process In the precursor synthesis step, first, the above-described lithium source, phosphate source, vanadium source, and reducing agent are introduced into water to prepare a mixture (aqueous solution) in which these are dispersed.
  • a mixture of a phosphoric acid source, a vanadium source, and water may be refluxed, and then a lithium source may be added to the refluxed mixture.
  • the whole amount of the mixture (aqueous solution) obtained in the above step is dried. Thereby, a precursor is obtained.
  • any existing apparatus capable of applying heat from the outside such as a dryer and an electric furnace, can be used.
  • the lithium source includes, for example, at least one selected from the group consisting of LiNO 3 , Li 2 Co 3 , LiOH, LiCl, Li 2 SO 4 and CH 3 COOLi.
  • the phosphoric acid source includes, for example, at least one selected from the group consisting of H 3 PO 4 , NH 4 H 2 PO 4 , (NH 4 ) 2 HPO 4 and Li 3 PO 4 .
  • Vanadium sources include, for example, at least one selected from the group consisting of V 2 O 5, VO 2, V 2 O 3 and NH 4 VO 3. Two or more lithium sources, two or more phosphoric acid sources, or two or more vanadium sources may be used in combination. In this case, the mixing ratio of each raw material is adjusted.
  • the reducing agent includes, for example, at least one selected from the group consisting of ascorbic acid, citric acid, tartaric acid, polyethylene, polyethylene glycol, hydrogen peroxide, and hydrazine. Two or more reducing agents may be used in combination, and the mixing ratio of each reducing agent can be appropriately adjusted and used.
  • the precursor synthesis step described above may be performed at room temperature, or may be performed at a temperature equal to or higher than room temperature using an oil bath or the like.
  • the precursor obtained in the precursor synthesis step is heat treated in an inert atmosphere or an oxidizing atmosphere. Thereby, LiVOPO 4 can be synthesized.
  • the heat treatment atmosphere includes, for example, at least one kind or a mixed gas of one or more kinds selected from the group consisting of an inert gas such as nitrogen and argon and an oxidizing gas such as oxygen and air.
  • the temperature of the heat treatment is preferably 400 ° C. to 650 ° C., more preferably 500 ° C. to 600 ° C.
  • the crystal structure, particle diameter, and the like of the obtained LiVOPO 4 can be controlled.
  • the method for producing a positive electrode active material according to the present embodiment is not limited to the above method, and the positive electrode active material may be synthesized by any existing method including a solid phase method, a hydrothermal method, a sol-gel method, and a gas phase method. Can do.
  • the carbon particles having a plate shape For the carbon particles having a plate shape according to the present embodiment, an existing flaky carbon material can be used. Moreover, the carbon particle which has plate shape can also be formed by press-forming the conventional carbon powders, such as acetylene black.
  • the positive electrode active material for a lithium ion secondary battery includes a mechanochemical method using mechanical energy such as friction and compression, and a spray that spray-drys a dispersion containing lithium vanadium phosphate and carbon particles having a plate shape.
  • An existing method for forming a coating layer on the particle surface such as a dry method, can be used.
  • the mechanochemical method is preferable because it is uniform and has high adhesion between the positive electrode active material and the carbon material having a plate shape.
  • an apparatus such as a mechanofusion apparatus or a planetary mill can be used.
  • a specific apparatus for the spray drying method a spray dryer or the like can be used.
  • the adhesion between the carbon material having a plate shape and the active material particles mainly composed of lithium vanadium phosphate can be adjusted by the manufacturing conditions in the conventional apparatus.
  • the adhesion of the coating layer can be adjusted by appropriately adjusting the angle, rotation speed, processing time, and material input amount of the processing apparatus.
  • ⁇ ⁇ Mix the above active material, binder and solvent.
  • a conductive material may be further added as necessary.
  • the solvent for example, water, N-methyl-2-pyrrolidone or the like can be used.
  • the mixing method of the components constituting the paint is not particularly limited, and the mixing order is not particularly limited.
  • the paint is applied to the current collectors 22 and 32.
  • the solvent in the paint applied on the current collectors 22 and 32 is removed.
  • the removal method is not particularly limited, and the current collectors 22 and 32 to which the paint has been applied may be dried, for example, in an atmosphere of 80 ° C. to 150 ° C.
  • the electrode on which the positive electrode active material layer 24 and the negative electrode active material layer 34 are formed in this way is subjected to a press treatment by a roll press device or the like as necessary.
  • the linear pressure of the roll press can be set to 1000 kgf / cm, for example.
  • the method for manufacturing a lithium ion secondary battery includes a positive electrode 20 containing the active material, a negative electrode 30, a separator 10 interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte solution containing a lithium salt. And a step of enclosing the outer body 50 in the exterior body 50.
  • the positive electrode 20 including the active material described above, the negative electrode 30 and the separator 10 are stacked, and the positive electrode 20 and the negative electrode 30 are heated and pressed with a press tool from a direction perpendicular to the stacking direction. 20, the separator 10 and the negative electrode 30 are brought into close contact with each other.
  • a lithium ion secondary battery can be manufactured by putting the laminate 40 into a bag-shaped outer package 50 prepared in advance and injecting a non-aqueous electrolyte solution containing the lithium salt.
  • the laminate 40 may be impregnated in advance with the nonaqueous electrolyte solution containing the lithium salt.
  • the present invention is not limited to the above embodiment.
  • the above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same function and effect. Are included in the technical scope.
  • the laminated film type lithium ion secondary battery has been described.
  • the present invention can be similarly applied to a lithium ion secondary battery having a structure in which a positive electrode, a negative electrode, and a separator are wound or folded. it can.
  • it can apply suitably also about lithium ion secondary batteries, such as a cylindrical shape, a square shape, and a coin type, as a battery shape. (Second embodiment)
  • a coating layer that contains graphene and covers at least a part of the surface of the active material particles is used as a carbon material that expands two-dimensionally.
  • the second embodiment is basically the same as the configuration of the first embodiment. Therefore, the description which overlaps with description of 1st embodiment is abbreviate
  • the lithium ion secondary battery in the second embodiment is the same as that in the first embodiment, detailed description thereof is omitted.
  • the positive electrode active material 200 includes a lithium vanadium phosphate represented by the following composition formula (1) and at least a part of the surface of the lithium vanadium phosphate 110 having single-layer graphene 121 or multilayer It is covered with a covering layer 120 containing at least one kind of graphene 121.
  • Li a (M) b (PO 4 ) c (1) M is VO or V, and 0.05 ⁇ a ⁇ 3.3, 0.9 ⁇ b ⁇ 2.2, and 0.9 ⁇ c ⁇ 3.3.
  • the lithium vanadium phosphate represented by the composition formula (1) does not need to have the stoichiometric oxygen amount represented by this composition formula, and includes a wide range of oxygen-deficient ones. In other words, those identified as the same composition system by X-ray diffraction or the like are targeted.
  • a part of vanadium is selected from the group consisting of W, Mo, Ti, Al, Ni, Co, Mn, Fe, Zr, Cu, Zn, and Yb. It may be substituted with one or more elements.
  • the content ratio of the active material particles mainly composed of lithium vanadium phosphate contained in the positive electrode active material according to this embodiment is 60 to 100% by mass, preferably 80 to 100% by mass, more preferably 96 to 99% by mass. %.
  • the content ratio of the coating layer contained in the positive electrode active material according to this embodiment is 0.5 to 10.0% by mass, preferably 1.0 to 8.0% by mass, and more preferably 2.0 to 4.%. 0% by mass.
  • Single-layer graphene is a single-layer material having a structure in which six-membered rings of carbon atoms are spread on a plane.
  • Multilayer graphene is a substance having a structure in which a plurality of graphenes are stacked, and a multilayer graphene having a thickness of 50 nm or less.
  • the single-layer graphene those having a specific surface area of 300 to 1500 m 2 g and a particle size (side part) of 0.2 to 1.0 ⁇ m are preferable.
  • the multilayer graphene preferably has a specific surface area of 80 to 500 m 2 g and a particle size (side part) of 0.2 to 5.0 ⁇ m.
  • the graphene content in the coating layer is 50 to 100% by mass, preferably 60 to 90% by mass, and more preferably 70 to 80% by mass.
  • the average primary particle diameter of lithium vanadium phosphate as shown in FIG. 2 is preferably 50 nm to 500 nm. If the average primary particle diameter is 50 nm or more, the number of times that the coating layer on the surface of the lithium vanadium phosphate in the electron movement path passes through the contact point connected to the other coating layer is reduced, and the electron conductivity is improved. This improves the rate characteristics. If the average primary particle diameter is 500 nm or less, the path through which electrons move inside the crystal of lithium vanadium phosphate having a low electron conductivity is shortened, thereby improving the rate characteristics.
  • the lithium vanadium phosphate is preferably primary particles or flat secondary particles. By being primary particles or flat secondary particles, the path through which electrons move inside the crystal of lithium vanadium phosphate is shortened, and the rate characteristics are improved.
  • lithium vanadium phosphates represented by the composition formula (1) a compound represented by LiVOPO 4 or Li 3 V 2 (PO 4 ) 3 is preferably used, and particularly LiVOPO 4 is preferably used.
  • the LiVOPO 4 preferably has a ⁇ -type (orthorhombic) crystal phase.
  • a higher charge / discharge capacity can be obtained as compared with the case of having an ⁇ -type (triclinic) or ⁇ -type (tetragonal) crystal phase.
  • a coating layer as shown in FIG. 2 is preferable when the surface of lithium vanadium phosphate particles is covered by 70% or more because the electron conductivity between the active material particles is further improved and the rate characteristics are improved. More preferably, the coating layer covers 80% or more of the particle surface of lithium vanadium phosphate. Even more preferably, the coating layer covers 95% or more of the particle surface of lithium vanadium phosphate.
  • the average thickness of the coating layer is preferably 3 nm to 100 nm. If the average thickness of the coating layer is 3 nm or more, the coating layer shows good electron conductivity, and if the average thickness of the coating layer is 100 nm or less, it shows good diffusibility of Li ions inside the coating layer. Therefore, rate characteristics are improved.
  • the coating layer preferably contains graphene and carbon black.
  • the coating layer preferably contains graphene and carbon black, it improves the electronic conductivity between graphene and the active material, between the graphene, and the diffusion of Li ions is improved by the penetration of the electrolyte into the void around the carbon black, Rate characteristics are improved.
  • the mass ratio of carbon black to graphene is 5% to 60%. If the mass ratio of carbon black to graphene is 5% or more, good electron conductivity and Li ion diffusibility can be obtained, and if the mass ratio is 60% or less, the distance between the graphenes inside the coating layer is close and good. Therefore, rate characteristics are improved.
  • the average thickness of graphene contained in the coating layer is preferably 20 nm or less. If the average thickness of graphene is 20 nm or less, since it follows the particle surface of lithium vanadium phosphate flexibly, better electron conductivity can be obtained, so that rate characteristics are improved.
  • the average thickness of a graphene is below the average thickness of the said coating layer.
  • the crystal phase of lithium vanadium phosphate contained in the positive electrode active material according to this embodiment can be identified by X-ray diffraction or the like.
  • the cross section of the particles can be observed and measured with a scanning electron microscope, a transmission electron microscope, etc. after cutting the positive electrode and polishing the cross section with a cross section polisher or an ion milling device.
  • the average thickness of the coating layer is the average value obtained by observing the cross section of 100 particles with a transmission electron microscope.
  • the average thickness of graphene is the average value obtained by observing a cross section of 100 graphenes included in the coating layer.
  • the mass ratio of graphene and carbon black can be measured by a transmission electron microscope or Raman spectroscopy.
  • the positive electrode current collector, the positive electrode binder, the negative electrode active material, the negative electrode current collector, the negative electrode conductive material, the negative electrode binder, the separator, and the non-aqueous electrolyte in the second embodiment are the same as in the first embodiment. Omitted.
  • the positive electrode active material 200 according to the present embodiment can be manufactured by the following coating layer forming process.
  • a coating layer containing graphene can be formed on the surface of lithium vanadium phosphate particles.
  • the method for forming the coating layer is not particularly limited, but a coating layer on the particle surface, such as a mechanochemical method using mechanical energy such as friction or compression, or a spray drying method in which a dispersion containing lithium vanadium phosphate and graphene is spray-dried is used.
  • a coating layer on the particle surface such as a mechanochemical method using mechanical energy such as friction or compression, or a spray drying method in which a dispersion containing lithium vanadium phosphate and graphene is spray-dried is used.
  • Existing methods of forming can be used.
  • the mechanochemical method is preferable because it can form a coating layer that is uniform and has good adhesion.
  • an apparatus such as a mechanofusion apparatus or a planetary mill can be used.
  • a specific apparatus for the spray drying method a spray dryer or the like can be used.
  • the adhesion between the coating layer containing graphene and the lithium vanadium phosphate particles can be adjusted by the coating layer forming conditions.
  • the adhesion of the coating layer can be adjusted by appropriately adjusting the angle, rotation speed, processing time, and material input amount of the processing apparatus.
  • the present invention is not limited to the above embodiment.
  • the above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same function and effect. Are included in the technical scope.
  • Example A1 (Creation of carbon particles)
  • the carbon particles in Example A1 were prepared by the following method.
  • a 0.5 g of acetylene black was weighed and pressurized with 100 Kgf using a hand press machine to form a thin acetylene black of ⁇ 16 mm.
  • the obtained thin circular acetylene black was sandwiched between PET films, and further pressed and rolled at a linear pressure of 2000 kgf / cm using a roll press.
  • a roll press machine was passed 10 times, and the obtained flaky acetylene black was lightly pulverized in an agate mortar to obtain carbon particles of Example A1.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A1 had a plate shape having an average plate surface diameter A of 200 nm, an average thickness B of 10 nm, and A / B of 20.
  • the positive electrode was punched into an electrode size of 18 mm ⁇ 22 mm using a mold to produce a positive electrode for a lithium ion secondary battery.
  • negative electrode active material 90 parts by mass of natural graphite powder and 10 parts by mass of PVDF were dispersed in NMP to prepare a slurry.
  • the obtained slurry was coated on a copper foil having a thickness of 15 ⁇ m, dried under reduced pressure at a temperature of 140 ° C. for 30 minutes, and then pressed using a roll press apparatus to obtain a negative electrode.
  • the negative electrode was punched into an electrode size of 19 mm ⁇ 23 mm using a mold to prepare a negative electrode for a lithium ion secondary battery.
  • the positive electrode for a lithium ion secondary battery and the negative electrode for a lithium ion secondary battery were laminated via a polyethylene separator to produce an electrode laminate. This was used as one electrode body, and an electrode laminate composed of four layers was produced by the same production method.
  • the said positive electrode and negative electrode are equipped with each mixture layer on both surfaces, they are comprised by 3 negative electrodes, 2 positive electrodes, and 4 separators.
  • a negative electrode lead made of nickel is attached to the protruding end of the copper foil not provided with the negative electrode mixture layer, while the positive electrode mixture layer is provided in the positive electrode of the electrode laminate.
  • the positive electrode lead made of aluminum was attached to the protruding end portion of the aluminum foil that was not formed by an ultrasonic fusion machine. Then, this electrode laminate was fused to an aluminum laminate film for an exterior body, and the laminate film was folded to insert the electrode body into the exterior body. A closed portion was formed by heat-sealing except for one side around the exterior body, and a non-aqueous electrolyte was injected from this opening. And the opening part of the said exterior body was sealed by heat sealing, decompressing with a vacuum sealing machine, and the laminate type battery cell in Example A1 was produced. The lithium ion secondary battery was manufactured in a dry room.
  • the current density during charging / discharging was set to 3C, and the rate characteristics of the battery cells were measured by repeating the above charging / discharging procedure.
  • the ratio of the discharge capacity C2 when the constant current discharge is performed at a current density of 3C to the discharge capacity C1 when the constant current discharge is performed at a current density of 0.1C is calculated according to an expression represented by (Expression 1) Rate characteristics were evaluated.
  • Evaluation of the rate characteristics was performed by preparing five battery cells and taking the average value of the obtained results.
  • Examples A2 to A32 change the charged amount of acetylene black when molding carbon particles, the press pressure of the hand press, the press pressure and the number of presses of the roll press, and the pulverization conditions of the obtained carbon particles.
  • carbon particles were produced in the same manner as in Example A1, except that the average plate surface diameter A and the average thickness B of the plate-like carbon particles were adjusted.
  • the battery cell was produced by using either LiVPO4 or Li3V2 (PO4) 3 as the carbon particle obtained in each Example, and lithium vanadium phosphate. The production method of the plate-like carbon particles and the details of the battery cell in each example are described below.
  • Example A2 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 2500 kgf / cm. A battery cell of Example A2 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A2 were in the form of a plate having an average plate surface diameter A of 1017 nm, an average thickness B of 10 nm, and A / B of 101.7.
  • Example A3 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 3000 kgf / cm. A battery cell of Example A3 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A3 were plate-shaped with an average plate surface diameter A of 3915 nm, an average thickness B of 10 nm, and A / B of 391.5.
  • Example A4 When pressurizing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was set to 4000 kgf / cm. A battery cell of Example A4 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A4 had a plate shape with an average plate surface diameter A of 8703 nm, an average thickness B of 10 nm, and A / B of 870.3.
  • Example A5 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 1000 kgf / cm. A battery cell of Example A5 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A5 had a plate shape having an average plate surface diameter A of 98 nm, an average thickness B of 10 nm, and A / B of 9.8.
  • Example A6 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 1200 kgf / cm. A battery cell of Example A6 was produced in the same manner as Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A6 were in the form of a plate having an average plate surface diameter A of 108 nm, an average thickness B of 10 nm, and A / B of 10.8.
  • Example A7 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was set to 1800 kgf / cm. A battery cell of Example A7 was produced in the same manner as Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A7 had a plate shape with an average plate surface diameter A of 982 nm, an average thickness B of 10 nm, and A / B of 98.2.
  • Example A8 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 1500 kgf / cm. A battery cell of Example A8 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A8 were in the form of a plate having an average plate surface diameter A of 627 nm, an average thickness B of 10 nm, and A / B of 62.7.
  • Example A9 Carbon particles were produced in the same manner as in Example A1, except that 0.1 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A9 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A9 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 3 nm, and A / B of 67.
  • Example A10 Carbon particles were produced in the same manner as in Example A1, except that 0.2 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A10 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A10 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 5 nm, and A / B of 40.
  • Example A11 Carbon particles were produced in the same manner as in Example A1 except that 0.8 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A11 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A11 had a plate shape having an average plate surface diameter A of 200 nm, an average thickness B of 20 nm, and A / B of 10.
  • Example A12 Carbon particles were produced in the same manner as in Example A1, except that 0.05 g of acetylene black was weighed, pressed and rolled, and the linear pressure of the roll press machine was 3000 kgf / cm. A battery cell of Example A12 was produced in the same manner as Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A12 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 0.3 nm, and A / B of 667.
  • Example A13 Carbon particles were produced in the same manner as in Example A1 except that 2.0 g of acetylene black was weighed, pressed and rolled, and the linear pressure of the roll press machine was 3000 kgf / cm. A battery cell of Example A13 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A13 had a plate shape having an average plate surface diameter A of 200 nm, an average thickness B of 20 nm, and A / B of 4.
  • Example A14 A battery cell of Example A14 was produced in the same manner as Example A5 except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A14 had a plate shape with an average plate surface diameter A of 80 nm, an average thickness B of 10 nm, and A / B of 8.
  • Example A15 A battery cell of Example A15 was produced in the same manner as Example A6 except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A15 were in the form of a plate having an average plate surface diameter A of 115 nm, an average thickness B of 10 nm, and A / B of 12.
  • Example A16 A battery cell of Example A16 was produced in the same manner as in Example A8 except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A16 had a plate shape having an average plate surface diameter A of 570 nm, an average thickness B of 10 nm, and A / B of 57.
  • Example A17 A battery cell of Example A17 was produced in the same manner as in Example A7, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A17 had a plate shape having an average plate surface diameter A of 971 nm, an average thickness B of 10 nm, and A / B of 97.
  • Example A18 A battery cell of Example A18 was produced in the same manner as in Example A2, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A18 had a plate shape with an average plate surface diameter A of 1028 nm, an average thickness B of 10 nm, and A / B of 103.
  • Example A19 A battery cell of Example A19 was produced in the same manner as in Example A3, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A19 were plate-shaped with an average plate surface diameter A of 4196 nm, an average thickness B of 10 nm, and A / B of 420.
  • Example A20 A battery cell of Example A20 was produced in the same manner as in Example A4, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A20 were in the form of a plate having an average plate surface diameter A of 9379 nm, an average thickness B of 10 nm, and A / B of 938.
  • Example A21 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 800 kgf / cm. A battery cell of Example A21 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A21 had a plate shape with an average plate surface diameter A of 51 nm, an average thickness B of 10 nm, and A / B of 5.1.
  • Example A22 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 4000 kgf / cm and the roll press machine was passed 15 times. A battery cell of Example A22 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A21 had a plate shape with an average plate surface diameter A of 9891 nm, an average thickness B of 10 nm, and A / B of 989.1.
  • Example A23 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 600 kgf / cm. A battery cell of Example A23 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A23 were in the form of a plate having an average plate surface diameter A of 46 nm, an average thickness B of 10 nm, and A / B of 4.6.
  • Example A24 When pressing and rolling, carbon particles were produced in the same manner as in Example A1, except that the linear pressure of the roll press machine was 4000 kgf / cm and the roll press machine was passed 20 times. A battery cell of Example A24 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A21 were in the form of a plate having an average plate surface diameter A of 10027 nm, an average thickness B of 10 nm, and A / B of 1002.7.
  • Example A25 Carbon particles were produced in the same manner as in Example A1, except that 0.12 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A25 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A25 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 2.8 nm, and A / B of 71.4.
  • Example A26 Carbon particles were produced in the same manner as in Example A1, except that 1.0 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A26 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A26 had a plate shape with an average plate surface diameter A of 200 nm, an average thickness B of 23 nm, and A / B of 8.7.
  • Example A27 Carbon particles were prepared in the same manner as in Example A1, except that 0.04 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press. A battery cell of Example A27 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A27 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 0.2 nm, and A / B of 1000.
  • Example A28 Carbon particles were prepared in the same manner as in Example A1, except that 2.5 g of acetylene black was weighed and pressurized with 200 Kgf using a hand press machine. A battery cell of Example A28 was produced in the same manner as in Example A1, except that the obtained carbon particles were used.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A28 were in the form of a plate having an average plate surface diameter A of 200 nm, an average thickness B of 51 nm, and A / B of 3.9.
  • Example A29 A battery cell of Example A29 was produced in the same manner as in Example A21 except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A29 were in the form of a plate having an average plate surface diameter A of 51 nm, an average thickness B of 10 nm, and A / B of 5.1.
  • Example A30 A battery cell of Example A30 was produced in the same manner as in Example A23, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A30 had a plate shape with an average plate surface diameter A of 47 nm, an average thickness B of 10 nm, and A / B of 4.7.
  • Example A31 A battery cell of Example A31 was produced in the same manner as in Example A22, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A31 had a plate shape with an average plate surface diameter A of 9861 nm, an average thickness B of 10 nm, and A / B of 986.1.
  • Example A32 A battery cell of Example A29 was produced in the same manner as in Example A24, except that Li 3 V 2 (PO 4 ) 3 having an average particle diameter of 30 nm was used as lithium vanadium phosphate.
  • the obtained carbon particles were observed using TEM.
  • the carbon particles according to Example A32 had a plate shape having an average plate surface diameter A of 10195 nm, an average thickness B of 10 nm, and A / B of 1019.5.
  • Example A1 A positive electrode active material was produced in the same manner as in Example A1 except that the acetylene black used in Example A1 was used as it was without being pressure-molded, and a battery cell was produced.
  • Comparative Example A2 A positive electrode active material was produced in the same manner as in Comparative Example A1 except that Li 3 V 2 (PO 4 ) 3 having an average particle size of 30 nm was used as lithium vanadium phosphate, and a battery cell was produced.
  • Example A3 A positive electrode active material was produced in the same manner as in Example A1, except that LiVOPO 4 , which is the material of the positive electrode active material used in Example A1, was replaced with orthorhombic LiFePO 4 having an average particle size of 30 nm. Was made.
  • LiVOPO 4 which is the material of the positive electrode active material used in Example A1 was replaced with orthorhombic LiFePO 4 having an average particle diameter of 30 nm, and the acetylene black used in Example A1 was used without being pressure-molded. Except for this, a positive electrode active material was produced in the same manner as in Example A1, and a battery cell was produced.
  • Example B1 (Creation of positive electrode) LiVOPO 4 having an average particle diameter of 170 nm as lithium vanadium phosphate and graphene having an average thickness of 2 nm are mixed at a mass ratio of 9: 1, processed using a Hosokawa Micron mechanofusion at a rotation speed of 3500 rpm, and LiVOPO 4 What formed the coating layer containing a graphene on the particle
  • a slurry was prepared by dispersing 96% of the positive electrode active material powder and 4% of polyvinylidene fluoride (PVDF) in N-methyl-2-pyrrolidone (NMP).
  • PVDF polyvinylidene fluoride
  • the obtained slurry was coated on an aluminum foil having a thickness of 15 ⁇ m, dried at a temperature of 120 ° C. for 30 minutes, and then pressed using a roll press apparatus at a linear pressure of 1000 kgf / cm to obtain a positive electrode.
  • the state of the coating layer containing graphene on the surface of LiVOPO 4 particles was measured using a transmission electron microscope (TEM), a scanning electron microscope (SEM), a Raman spectroscope, a cross section polisher, and an ion milling device.
  • TEM transmission electron microscope
  • SEM scanning electron microscope
  • Raman spectroscope Raman spectroscope
  • a cross section polisher polisher
  • ion milling device An ion milling device
  • a negative electrode, a non-aqueous electrolyte solution, and a separator were prepared in the same manner as in Example 1.
  • Example B1 (Production of battery)
  • the positive electrode, the negative electrode, and the separator were laminated to constitute a power generation element, and a battery cell of Example B1 was produced using this and the non-aqueous electrolyte.
  • C rate The current density for charging or discharging a battery cell in one hour is called 1C.
  • the current density during charging or discharging is expressed using a constant multiple of the C rate (for example, a current density half of 1C is 0.5C). Expressed as)
  • the measurement of rate characteristics was basically performed by the same method as in the first example. However, in Example 2, the current density during charging / discharging was set to 1C (3C in the first example).
  • Examples B2 to B25, Comparative Examples B1 to B7 In Examples B2 to B25 and Comparative Examples B1 to B7, the presence or absence of graphene in the coating layer, the composition / crystal phase / particle size of lithium vanadium phosphate, the thickness of the coating layer containing graphene, and the graphene contained A battery cell was prepared and evaluated in the same manner as in Example B1 by changing the thickness, the presence or absence of carbon black in the coating layer, and the presence or absence of graphene coating. The results are shown in Table 2.
  • Table 2 shows that the rate characteristics are improved by forming a coating layer containing graphene on the surface of lithium vanadium phosphate.
  • the example shows a higher rate characteristic and cycle characteristic than the comparative example.

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Abstract

Le but de la présente invention est de fournir une substance active d'électrode positive pour des batteries secondaires au lithium-ion ayant des caractéristiques de taux élevé, une électrode positive pour batteries secondaires au lithium-ion, et une batterie secondaire au lithium-ion l'utilisant. La présente invention concerne une substance active d'électrode positive pour batteries secondaires au lithium-ion, caractérisée en ce qu'elle comprend: ayant un matériau de carbone à expansion bidimensionnelle et des particules de substance active ayant comme composant principal un phosphate de lithium-vanadium indiqué par la formule de composition Lia(M)b(PO4)c (M étant VO ou V, 0,05 ≤ a ≤ 3,3, 0,9 ≤ b ≤ 2,2, et 0,9 ≤ c ≤ 3,3.); Et le matériau carboné contenant au moins partiellement des particules de carbone en forme de plaque ou du graphène et recouvrant au moins une partie de la surface des particules de substance active.
PCT/JP2017/027262 2016-07-27 2017-07-27 Substance active d'électrode positive pour batteries secondaires au lithium-ion, électrode positive pour batteries secondaires au lithium-ion, et batterie secondaire au lithium-ion l'utilisant WO2018021480A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2016-147479 2016-07-27
JP2016147478A JP2019164880A (ja) 2016-07-27 2016-07-27 リチウムイオン二次電池用正極活物質、リチウムイオン二次電池用正極およびこれを用いたリチウムイオン二次電池
JP2016-147478 2016-07-27
JP2016147479A JP2019164881A (ja) 2016-07-27 2016-07-27 リチウムイオン二次電池用正極活物質、リチウムイオン二次電池用正極およびこれを用いたリチウムイオン二次電池

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WO2021014257A1 (fr) * 2019-07-19 2021-01-28 株式会社半導体エネルギー研究所 Procédé de création d'une suspension d'électrode, procédé de création d'électrode, procédé de création d'électrode positive, électrode pour batterie secondaire, et électrode positive pour batterie secondaire

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CN109860601A (zh) * 2019-04-03 2019-06-07 山东星火科学技术研究院 一种石墨烯/碳纳米管复合改性锂电池正极材料的制备方法
WO2021014257A1 (fr) * 2019-07-19 2021-01-28 株式会社半導体エネルギー研究所 Procédé de création d'une suspension d'électrode, procédé de création d'électrode, procédé de création d'électrode positive, électrode pour batterie secondaire, et électrode positive pour batterie secondaire

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