WO2014017617A1 - リチウム二次電池用正極活物質、それを用いたリチウム二次電池用正極及びリチウム二次電池、並びにリチウム二次電池用正極活物質の製造方法 - Google Patents
リチウム二次電池用正極活物質、それを用いたリチウム二次電池用正極及びリチウム二次電池、並びにリチウム二次電池用正極活物質の製造方法 Download PDFInfo
- Publication number
- WO2014017617A1 WO2014017617A1 PCT/JP2013/070251 JP2013070251W WO2014017617A1 WO 2014017617 A1 WO2014017617 A1 WO 2014017617A1 JP 2013070251 W JP2013070251 W JP 2013070251W WO 2014017617 A1 WO2014017617 A1 WO 2014017617A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- positive electrode
- active material
- lithium secondary
- electrode active
- secondary battery
- Prior art date
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- 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 a lithium secondary battery, a positive electrode for a lithium secondary battery and a lithium secondary battery using the same, and a method for producing a positive electrode active material for a lithium secondary battery.
- lithium cobaltate As a positive electrode active material for a lithium secondary battery, lithium cobaltate has conventionally been the mainstream, and a lithium secondary battery using this has been widely used.
- cobalt which is a raw material of lithium cobaltate, has been studied as a substitute material because it is less expensive and expensive.
- Lithium manganate having a spinel structure and lithium nickelate have been studied as substitutes for lithium cobaltate.
- lithium manganate has a problem that the discharge capacity is not sufficient and manganese is eluted at high temperature.
- lithium nickel oxide can be expected to have a high capacity, but its thermal stability at high temperature is not sufficient.
- a polyanion-based compound having a polyanion an anion formed by binding a plurality of oxygen to one typical element such as PO 4 3- , BO 3 3- , SiO 4 4- ) in a crystal structure is It is excellent and expected as a positive electrode active material for lithium secondary batteries. This is because the polyanion bond (PO bond, BO bond, Si-O bond, etc.) is strong and oxygen is not released even at high temperature.
- polyanionic compounds have low electron conductivity and ion conductivity, and there is a problem that the discharge capacity can not be sufficiently extracted. This is because the electrons are localized to the above-described strong polyanion bond.
- Patent Document 1 proposes a technique for covering the surface of a polyanion-based compound with carbon to improve the electron conductivity with respect to the problem of the polyanion-based compound described above. Further, Non-Patent Document 1 proposes a technique for reducing the particle diameter of the polyanionic compound to increase the reaction area and shortening the diffusion distance to improve the electron conductivity and the ion conductivity.
- the method of carbon-coating a polyanion-based compound includes a method of mixing the compound with acetylene black or graphite and adhering them with a ball mill or the like, a method of mixing the compound with a sugar, an organic acid, or an organic substance such as pitch and firing There is. Further, as a method for reducing the particle size of the polyanion-based compound, there are a method of lowering the baking temperature of the compound, a method of mixing the compound with a carbon source, and a method of suppressing crystal growth.
- any of the methods described above may lead to a decrease in the crystallinity of the polyanion compound.
- the decrease in crystallinity of the positive electrode active material leads to a decrease in discharge capacity and rate characteristics.
- a positive electrode active material for a lithium secondary battery comprising carbon-coated polyanionic compound particles, comprising:
- the polyanion compound has a structure represented by the following (Chemical Formula 1),
- the roughness factor represented by the following (formula 1) of the polyanionic compound is 1 to 2
- the present invention provides a positive electrode active material for a lithium secondary battery, wherein an average primary particle diameter of the polyanionic compound is 10 to 150 nm.
- LixMAyOz ⁇ (Chemical formula 1) (Wherein M contains at least one transition metal element, A is a typical element which forms an anion by bonding with oxygen O, and 0 ⁇ x ⁇ 2, 1 ⁇ y ⁇ 2, 3 ⁇ z ⁇ 7 .)
- the metal M contained in the chemical formula 1 contains a transition metal element such as Fe, Mn, Ni, or Co as an essential component. In addition, some other typical element may be contained as another component.
- Another aspect of the present invention is a method for producing a polyanion compound, particularly a positive electrode active material for a lithium secondary battery having an olivine type structure, wherein a raw material containing a transition metal compound as a metal source and a phosphorus compound is mixed. And baking the mixed raw materials, mixing the carbon source with the calcined body, and baking the material, wherein the baking temperature is equal to or higher than the crystallization temperature of the positive electrode active material, and the crystallization temperature is It is characterized by being below the temperature which added 200 degreeC.
- the present invention also provides a method of producing a positive electrode active material for a lithium secondary battery, a positive electrode for a lithium secondary battery produced using the positive electrode active material for a lithium secondary battery, and a lithium secondary battery.
- a highly safe polyanion compound is used as a positive electrode active material for a lithium secondary battery, and the discharge capacity and rate characteristics are improved compared to a lithium secondary battery using a conventional polyanion type positive electrode active material.
- a high positive electrode active material for lithium secondary battery can be provided.
- security and battery performance compatible, the positive electrode for lithium secondary batteries, and a lithium secondary battery can be provided.
- any one or more of PO 4 3- , BO 3 3- , and SiO 4 4- are applicable.
- Fe, Mn, Co, Ni etc. are represented as a transition metal contained in the metal part (M) of a polyanion type compound. Note that part of M may contain a typical element such as Mg.
- the particle diameter of the positive electrode active material particles is preferably within a predetermined range. In the case of the present invention, it is preferable that the average primary particle size is 10 to 150 nm. Moreover, it is preferable to contribute to the improvement of the packing density by making the primary particles into secondary particles in a state of being aggregated by sintering or the like before the slurry formation.
- a highly safe polyanionic compound is used, and at the same time, high capacity, high rate characteristics, and high energy density are achieved compared to a lithium secondary battery using a conventional polyanionic positive electrode active material. And, it is possible to provide a positive electrode active material for a lithium secondary battery having good smoothness and uniformity of the electrode. As a result, the performance of the positive electrode for a lithium secondary battery manufactured using the positive electrode active material for a lithium secondary battery, and the lithium secondary battery can be improved.
- the positive electrode active material for a lithium secondary battery can be used for the positive electrode as secondary particles as described above.
- the method for producing a positive electrode active material comprising secondary particles of a polyanionic compound comprises the steps of mixing a lithium compound, a transition metal compound to be a metal element source, and a phosphoric acid compound, calcining the mixture, and a carbon source in a calcined body. And a step of forming secondary particles, and a step of firing.
- the present invention can add the following improvements and changes to the above-described positive electrode active material for a lithium secondary battery.
- the polyanion-based compound has an olivine type structure represented by the following (Chemical formula 2).
- LiMPO 4 ⁇ (Chemical formula 2) (However, M is at least one of Fe, Mn, Co and Ni.)
- M in the polyanionic compound having an olivine type structure contains Mn and Fe, and the ratio of Fe occupying M is more than 0 mol% and 50 mol% or less in molar ratio.
- the content of carbon is 2 to 5% by mass.
- the positive electrode active material for a lithium secondary battery according to the present invention is a positive electrode active material for a lithium secondary battery including a carbon-coated polyanion-based compound particle, wherein the polyanion-based compound particle is It has a structure represented by (Chemical formula 1).
- Non-aqueous electrolytes of lithium secondary batteries are widely known in which a supporting salt (electrolyte) such as lithium hexafluorophosphate is dissolved in a non-aqueous solvent such as ethylene carbonate (EC) or propylene carbonate (PC). ing.
- a non-aqueous solvent such as ethylene carbonate (EC) or propylene carbonate (PC).
- EC ethylene carbonate
- PC propylene carbonate
- these non-aqueous solvents are flammable (for example, the flash points of EC and PC are 130 to 140 ° C.), they can in principle ignite if there is a fire species.
- the constituent material releases oxygen when the lithium secondary battery is in a high temperature state due to overcharging or the like, the oxygen may react with the non-aqueous electrolyte to cause ignition.
- the bond of the polyanion (A-O bond in (Chemical formula 1)) is strong, and oxygen is not released even at high temperature. Therefore, even when the temperature of the lithium secondary battery becomes high, the electrolyte does not burn. Therefore, a highly safe lithium secondary battery can be provided.
- the said polyanion type compound is a compound which has an olivine type structure represented by said (Chemical formula 2).
- M in the polyanionic compound having an olivine type structure contains Mn and Fe, and the ratio of Fe occupying M is preferably more than 0 mol% and 50 mol% or less in molar ratio.
- M in (Chemical Formula 1) the resistance decreases as the proportion of Fe increases, and the average voltage increases as the proportion of Mn increases. The higher the average voltage, the higher the energy density (capacitance ⁇ voltage). However, if the Mn content is 100%, the resistance is too high to obtain a capacity, and the energy density also decreases.
- M in the polyanionic compound contains Mn and Fe, and the ratio of Fe to M is more than 0 mol% and 50 mol% or less in molar ratio.
- the polyanion compound of the present invention has a roughness factor of 1 to 2 represented by the above (formula 1).
- the roughness factor refers to the specific surface area (a) measured using the BET method and the shape of the primary particles in the positive electrode active material containing polyanionic compound particles, assuming that the shape of the primary particles is a true sphere, X-ray It is a ratio (a / b) of the specific surface area (b) calculated from the average primary particle diameter calculated using Scherrer's formula from the diffraction measurement result, and indicates the degree of surface roughness of the particles. As the surface roughness of the particles is larger and the number of irregularities is larger, the value of the roughness factor is larger.
- the value of the roughness factor decreases. That is, since the specific surface area of the particles is larger as the value of the roughness factor is larger, the reactivity between the positive electrode active material and the electrolyte becomes higher.
- the roughness factor of the positive electrode active material of the present invention is 1 to 2, and this value is compared with the value (less than 1) of the polyanion-based positive electrode active material manufactured by the conventional manufacturing method. You are big. Therefore, the lithium secondary battery produced using the positive electrode active material of the present invention is more reactive between the positive electrode active material and the electrolyte than a lithium secondary battery using a conventional polyanion-based positive electrode active material having the same particle diameter. Can achieve high capacity, high rate characteristics, and high energy density. When the roughness factor is less than 1, the effect of enhancing the reactivity between the positive electrode active material and the electrolyte described above can not be obtained.
- a positive electrode active material when it becomes larger than 2, the shape of a positive electrode active material will remove
- “1 to 2” means 1 or more and 2 or less. The method for producing the positive electrode active material for a lithium secondary battery of the present invention having a roughness factor of 1 to 2 will be described in detail later.
- the positive electrode active material of the present invention is a secondary particle in which a large number of primary particles having an average particle diameter of 10 to 150 nm are collected.
- the average primary particle diameter is less than 10 nm, aggregation is likely to occur, particles of about several mm may occur in the slurry, and when it exceeds the electrode thickness, the smoothness and uniformity of the electrode are degraded.
- the average primary particle diameter is larger than 150 nm, the specific surface area becomes small, and it becomes difficult to sufficiently ensure the reactivity between the positive electrode active material and the electrolyte.
- the specific surface area of the positive electrode active material increases as the average primary particle diameter of the positive electrode active material decreases, and the reactivity between the positive electrode active material and the electrolyte increases to improve the characteristics.
- the particle diameter is smaller, aggregation is more likely to occur, and the smoothness and uniformity of the electrode are reduced.
- the positive electrode active material of the present invention is larger in roughness factor than the conventional positive electrode active material using polyanionic compound particles as described above, it is preferable that the average primary particle diameter has good electrode smoothness and uniformity. Even in the range that can be provided (10 to 150 nm), higher capacity, higher rate characteristics, and higher energy density can be achieved than ever before.
- the average primary particle size is a value determined from a pattern obtained by powder X-ray diffraction measurement.
- the measuring method and the calculating method of the average primary particle diameter will be described in detail in Examples.
- the polyanion-based compound particles of the present invention are coated with carbon, and the content of the carbon is preferably 2 to 5% by mass in the positive electrode active material.
- carbon is considered to be present inside the particle or between the particle and the particle in addition to the surface of the particle.
- the "carbon content” mentioned above also includes the amount of carbon present other than the surface of the polyanion compound particles. If the carbon content is less than 2% by mass, the electron conductivity is reduced, and sufficient battery performance can not be obtained. When the carbon content is more than 5% by mass, the energy density decreases and the specific surface area increases, and the smoothness and the uniformity of the electrode decrease.
- the "coating" in the present invention is used in the meaning including the above-mentioned form.
- the manufacturing method of the positive electrode active material for lithium secondary batteries of this invention is demonstrated.
- the present invention is directed to a positive electrode active material that needs to be used with a reduced particle diameter of 200 nm or less, including compounds having an olivine structure.
- a positive electrode active material that needs to be used with a reduced particle diameter of 200 nm or less, including compounds having an olivine structure.
- aggregation is apt to occur, whereby the specific surface area is reduced and the roughness factor is easily reduced. Therefore, in order to increase the roughness factor, it is necessary to improve the surface roughness of the active material particles and to carry out a manufacturing method that prevents aggregation and sintering.
- the method for producing a positive electrode active material for a lithium secondary battery according to the present invention includes (i) mixing of raw materials, (ii) pre-sintering, (iii) carbon source mixing, and (ix) main firing, twice by the solid phase method Carry out the above.
- the production of the positive electrode active material by the solid phase method is to generate a solid phase reaction by heating in a state where the raw materials are sufficiently mixed according to the target composition.
- the production flow of the positive electrode active material according to the present invention is shown in FIG.
- the production method of the present invention has two or more solid phase firing steps in the production of a positive electrode active material, and at least one firing step among firing steps other than the final firing step (hereinafter referred to as main firing).
- pre-baking is characterized in that it is carried out at a temperature above the crystallization temperature in the solid phase reaction and at a temperature that does not greatly exceed it, and it is preferable to bake at 600.degree. .
- Pre-baking is preferably performed in an oxidizing atmosphere, such as air, and the main baking is performed in a non-oxidizing atmosphere.
- the pre-baking and the main-baking can be performed twice or more.
- the particles produced by such a method have a large roughness factor and a large specific surface area as compared with particles having the same particle diameter and a small roughness factor, and are excellent in the reactivity with the electrolyte.
- the particle size is increased for particles with a large roughness factor, it is possible to lower the reaction resistance (increase the reactivity with the electrolyte) while suppressing the adverse effect of reducing the particle size (aggregation of particles etc.), When the particle size is reduced, particles with lower resistance can be obtained.
- the steps described above will be described in order.
- the positive electrode active material for a lithium secondary battery of the present invention can obtain microcrystals by performing calcination at a temperature above the crystallization temperature and at a temperature not significantly exceeding the crystallization temperature.
- primary particles containing a large number of such microcrystals can be obtained.
- Such primary particles have large surface irregularities and a large roughness factor.
- the size of microcrystals constituting primary particles depends on the particle diameter of the raw material and the like. Since the surface roughness increases as the crystallites become smaller, the particle diameter of the material of the positive electrode active material is desirably as small as possible (for example, 1 ⁇ m or less).
- the crystals generated during calcination may be coarsened, or heterophases (compounds other than polyanionic compounds such as oxides of Mn or Fe, MnP 2 O 7 etc.) may be generated. It is desirable to be mixed more uniformly in order to
- a method of mixing the raw materials uniformly there is a method of mechanically grinding and mixing the raw materials using a bead mill or the like, or drying the raw materials in a solution state using an acid, an alkali, a chelating agent, etc.
- the method of mixing is preferred.
- the method of mixing in a solution state is advantageous for the precipitation of finer crystals because the raw materials are mixed at the molecular level.
- lithium acetate, lithium carbonate, lithium hydroxide or the like can be used as a raw material of Li.
- a raw material of M at least one of acetate, oxalate, citrate, carbonate, tartrate and the like can be used.
- a raw material of A y O z a compound in an acid state of polyanion, or a salt in which the acid is neutralized (ammonium salt, lithium salt, etc.) can be used.
- a compound in an acid state of polyanion, or a salt in which the acid is neutralized (ammonium salt, lithium salt, etc.) can be used.
- a salt in which the acid is neutralized (ammonium salt, lithium salt, etc.)
- PO 4 can be used lithium dihydrogen phosphate, ammonium dihydrogen phosphate, and the like diammonium hydrogen phosphate.
- the pre-baking temperature be equal to or higher than the crystallization temperature of the polyanionic compound and not significantly exceed the crystallization temperature. If the temperature is lower than the crystallization temperature, a large amount of unreacted material is generated by calcination. These non-reacted substances are transferred to the active material phase in the main firing to be described later, but at that time, a plurality of particles are bonded to each other to cause aggregation and sintering of the particles. When aggregation or sintering of particles occurs, the specific surface area decreases and the reactivity decreases.
- the particle diameter after production can be increased by raising the pre-sintering temperature, but if the pre-sintering temperature is too high, the particles become coarse and the specific surface area of the positive electrode active material decreases, and the positive electrode active The reaction area between substance and electrolyte is reduced.
- the preferable range of the pre-baking temperature also differs.
- the crystallization temperature is around 420 ° C. (Source: Robert Dominko, Marjan Bele, Jean-Michel Goupil, Miran Gaberscek, Darko Hanzel, Iztok Arcon, and Janez Jamnik Since it is "Wired Porous Cathode Materials: A Novel Concept for Synthesis of LiFePO4" Chemistry of Materials 19 (2007), pp. 2960-2969.), Firing at 420 ° C. or higher is necessary.
- the temperature is more preferably 440 to 500 ° C. If the temperature is 440 ° C. or higher, the entire sample will be at the crystallization temperature or higher even if there is some temperature unevenness in the sample. When the temperature is 500 ° C. or less, the average primary particle diameter after temporary firing is 100 nm or less, and particles having a length of 100 nm or less can be obtained after the main firing described later.
- the atmosphere for temporary firing is preferably an oxidizing atmosphere.
- an oxidizing atmosphere By pre-baking in an oxidizing atmosphere and in the above-mentioned temperature range, the organic matter derived from the raw material (including a part of the organic matter such as carbon) disappears, and these can be prevented from being mixed inside the crystal. . Therefore, in the oxidizing atmosphere, the crystallinity can be improved more than in the case of firing in an inert atmosphere or a reducing atmosphere.
- the organic substances are uniformly mixed in the raw materials, so the organic substances are easily taken into the crystal in an inert atmosphere or a reducing atmosphere.
- the calcination temperature is preferably 400 ° C. or higher regardless of the above-mentioned crystallization temperature, so that the calcination is preferably 420 to 600 ° C.
- a ball mill or a bead mill as a method which mixes a carbon source with the crystallites obtained by calcination and coats them, and can also make the crystallites finer.
- a plurality of particles (primary particles) as described above are aggregated to form a secondary particle in an integrated form. By forming into secondary particles, the particle size is increased to a certain extent, which contributes to the improvement of electrode volume density and the like. When performing secondary particle formation, it is preferable to carry out before main baking.
- (Iv) Main Firing In the main firing, the carbon source coated on the temporary firing body is carbonized to improve the conductivity of the positive electrode active material and to improve the crystallinity or crystallization of the active material particles. In this firing, it is necessary to carbonize the organic substance (carbon source) to prevent oxidation of the metal element, so it is performed in an inert atmosphere or a reducing atmosphere.
- the main firing temperature is preferably 600 ° C. or higher in order to carbonize the organic matter.
- carbon source can be carbonized and conductivity can be provided.
- the temperature is 850 ° C. or less, the compound having an olivine structure does not undergo decomposition. More desirably, the temperature is 700 to 750.degree. In this temperature range, the conductivity of carbon can be sufficiently improved, and the formation of impurities due to the reaction of carbon and a compound having an olivine structure can be suppressed.
- a hydrothermal synthesis method in general, as a method for producing a compound having an olivine structure other than the solid phase method, a hydrothermal synthesis method can be mentioned.
- the hydrothermal synthesis method dispersed primary particles free of impurities are obtained.
- the particles produced by the hydrothermal synthesis method have a smooth surface. This is to perform nuclear growth in accordance with the growth rate of the crystal face. Compared with such smooth particles, the particles of the present production method have a larger specific surface area at the same particle diameter, and the reactivity with the electrolyte is higher.
- temporary baking may be performed twice or more, if the conditions of the present invention are satisfied.
- the positive electrode for a lithium secondary battery of the present invention has a configuration in which a positive electrode mixture containing the above-described positive electrode active material of the present invention and a binder is formed on a current collector.
- a conductive aid may be added to the positive electrode mixture, if necessary, in order to compensate for the electron conductivity.
- the materials for the binder, the conductive additive, and the current collector and conventional materials can be used.
- PVDF polyvinylidene fluoride
- polyacrylonitrile are suitable.
- the type of binding agent is not particularly limited as long as it has sufficient binding properties.
- the conductive aid carbon-based conductive aids such as acetylene black and graphite powder are suitable. Since the positive electrode active material according to the present invention has a high specific surface area, it is desirable for the conductive support to have a large specific surface area in order to form a conductive network, and specifically, acetylene black is particularly preferable. By using a binder excellent in adhesion as described above and mixing a conductive aid to impart conductivity, a strong conductive network is formed. Therefore, the conductivity of the positive electrode can be improved, and the capacity and rate characteristics can be improved.
- a support having conductivity such as aluminum foil is suitable.
- FIG. 1 is a half sectional schematic view showing an example of a lithium secondary battery to which the invention is applied.
- the positive electrode 10 and the negative electrode 6 are wound in a state in which the separator 7 is sandwiched so as not to be in direct contact with each other to form an electrode group.
- the structure of an electrode group is not limited to winding of shapes, such as cylindrical shape and flat shape, What laminated
- the positive electrode lead 3 is attached to the positive electrode 10, and the negative electrode lead 9 is attached to the negative electrode 6.
- the leads 3 and 9 can have any shape such as wire, foil, plate and the like. The structure and material are selected so as to reduce the electrical loss and secure the chemical stability.
- the electrode group is housed in the battery case 5, and the inserted electrode group is not in direct contact with the battery case 5 by the insulating plate 4 provided at the top of the battery case 5 and the insulating plate 8 provided at the bottom. It has become. Furthermore, a non-aqueous electrolyte (not shown) is injected into the battery container 5.
- the shape of the battery case 5 is usually selected to have a shape (for example, a cylindrical shape, a flat long cylindrical shape, a prism, etc.) that matches the shape of the electrode group.
- any material for example, a thermosetting resin, a glass hermetic seal, etc. which does not react with the non-aqueous electrolytic solution and is excellent in airtightness is preferable.
- the material of the battery case 5 is selected from materials having corrosion resistance to the non-aqueous electrolyte, such as aluminum, stainless steel, and nickel-plated steel.
- the attachment of the battery cover 1 to the battery case 5 may be performed by caulking, adhesion, or the like, in addition to welding.
- the positive electrode 10 constituting the lithium secondary battery is formed by applying and drying a positive electrode mixture slurry containing a positive electrode active material on one side or both sides of a positive electrode current collector, and compression molding using a roll press machine etc. It is produced by cutting to the size of.
- a positive electrode mixture slurry containing a positive electrode active material on one side or both sides of a positive electrode current collector, and compression molding using a roll press machine etc. It is produced by cutting to the size of.
- an aluminum foil having a thickness of 10 to 100 ⁇ m, a perforated foil made of aluminum having a thickness of 10 to 100 ⁇ m and a hole diameter of 0.1 to 10 mm, an expanded metal, a foam aluminum plate or the like is used for the current collector of the positive electrode.
- stainless steel, titanium, etc. can be applied as the material.
- negative electrode 6 constituting a lithium secondary battery is formed by applying and drying a negative electrode mixture slurry containing a negative electrode active material on one side or both sides of a negative electrode current collector, and then compression molding using a roll press machine or the like. It is produced by cutting into a predetermined size.
- a copper foil having a thickness of 10 to 100 ⁇ m, a perforated copper foil having a thickness of 10 to 100 ⁇ m and a hole diameter of 0.1 to 10 mm, an expanded metal, a foamed copper plate, etc. are used for the current collector of the negative electrode.
- stainless steel, titanium, nickel and the like are also applicable.
- the method of applying the positive electrode mixture slurry and the negative electrode mixture slurry there is no particular limitation on the method of applying the positive electrode mixture slurry and the negative electrode mixture slurry, and a conventional method (for example, a doctor blade method, a dipping method, a spray method, etc.) can be used.
- a conventional method for example, a doctor blade method, a dipping method, a spray method, etc.
- the positive electrode active material of the present invention As a positive electrode active material used for the positive electrode 10, the positive electrode active material of the present invention described above is used. A binder, a thickener, a conductive agent, a solvent, and the like are mixed as needed with respect to the positive electrode active material to prepare a positive electrode mixture slurry.
- the negative electrode active material used for the negative electrode 6 is not particularly limited as long as it is a material capable of inserting and extracting lithium ions.
- artificial graphite, natural graphite, amorphous carbon, non-graphitizable carbons, activated carbon, coke, pyrolytic carbon, metal oxides, metal nitrides, lithium metal or lithium metal alloy and the like can be mentioned. Any one of these or a mixture of two or more can be used.
- amorphous carbon is a material having a small volume change rate at the time of insertion and extraction of lithium ions, it is preferable to include amorphous carbon as a negative electrode active material because charge and discharge cycle characteristics are enhanced.
- a binder, a thickener, a conductive agent, a solvent, and the like are mixed with the negative electrode active material as necessary to prepare a negative electrode mixture slurry.
- conductive polymer materials for example, polyacene, polyparaphenylene, polyaniline, polyacetylene, etc.
- conductive polymer materials for example, polyacene, polyparaphenylene, polyaniline, polyacetylene, etc.
- binder There is no particular limitation on the binder, the thickener and the solvent used for the mixture slurry, and the same one as before can be used.
- the separator 7 is preferably a porous body (for example, with a pore diameter of 0.01 to 10 ⁇ m and a porosity of 20 to 90%) because lithium ions need to be transmitted during charge and discharge of the secondary battery.
- a material of the separator 7 a multilayer structure sheet obtained by welding a polyolefin-based polymer sheet (for example, polyethylene or polypropylene) or a polyolefin-based polymer sheet and a fluorine-based polymer sheet (for example, polytetrafluoroethylene) Or a glass fiber sheet can be used conveniently.
- a mixture of ceramics and a binder may be formed in a thin layer on the surface of the separator 7.
- lithium salts such as LiPF 6 , LiBF 4 , LiCF 3 SO 3 , LiN (SO 2 CF 3 ) 2 , LiN (SO 2 F) 2 can be used alone or in combination.
- a solvent for dissolving the lithium salt linear carbonates, cyclic carbonates, cyclic esters, nitrile compounds and the like can be used. Specifically, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethoxyethane, ⁇ -butyrolactone, n-methyl pyrrolidine, acetonitrile and the like.
- polymer gel electrolytes and solid electrolytes can also be used as electrolytes.
- a solid polymer electrolyte polymer electrolyte
- ion conductive polymers such as ethylene oxide, acrylonitrile, polyvinylidene fluoride, methyl methacrylate, polyethylene oxide of hexafluoropropylene, and the like can be suitably used.
- the separator 7 can be omitted.
- the positive electrode, the negative electrode, the separator, and the electrolyte described above can be used to form various types of lithium secondary batteries such as cylindrical batteries, square batteries, and laminate batteries.
- Example 1 a positive electrode active material composed of primary particles of a polyanion compound is produced, and the results of evaluation of the characteristics of the electrode by the model cell are described.
- Example 1-1 (I) Mixing of raw materials As metal sources, iron citrate (FeC 6 H 5 O 7 ⁇ n H 2 O) and manganese acetate tetrahydrate (Mn (CH 3 COO) 2 ⁇ 4 H 2 O) are used, and Fe and It weighed so that Mn might be set to 2: 8, and this was melt
- FeC 6 H 5 O 7 ⁇ n H 2 O iron citrate
- lithium dihydrogen phosphate H 2 LiO 4 P
- an aqueous lithium acetate solution CH 3 CO 2 Li
- the reason for using this preparation composition is to prevent cation mixing and to compensate volatilization of Li during firing.
- lithium phosphate Li 3 PO 4
- this material has high Li ion conductivity, which is one of the reasons that the adverse effect is small.
- the solution obtained above was dried using a spray dryer, and dried under the conditions of an inlet temperature of 195 ° C. and an outlet temperature of 80 ° C. to obtain a raw material powder.
- the raw material powder is in a state in which each element is uniformly dispersed in a citric acid matrix.
- sucrose is added as a carbon source and a particle size control agent at a ratio of 7 mass% in mass ratio, and pulverized for 2 hours using a ball mill. Mixed.
- the positive electrode active material was obtained by the above steps.
- the positive electrode was created using the positive electrode active material obtained above.
- the method of producing the electrode will be described below.
- the positive electrode active material, the conductive agent, the binder, and the solvent were mixed in a mortar to prepare a positive electrode mixture slurry.
- Acetylene black (Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as a conductive agent, modified polyacrylonitrile as a binder, and N-methyl-2-pyrrolidone (NMP) as a solvent.
- the binder was a solution dissolved in NMP.
- the composition of the electrode was such that the mass ratio of the positive electrode active material, the conductive material, and the binder was 82.5: 10: 7.5.
- the positive electrode material mixture slurry is applied to one side of a 20 ⁇ m-thick positive electrode current collector (aluminum foil) by a doctor blade method so that the coating amount is 5 to 6 mg / cm 2 , The resultant was dried at 80 ° C. for 1 hour to form a positive electrode mixture layer (thickness 38 to 42 ⁇ m).
- the positive electrode mixture layer was punched into a disk shape having a diameter of 15 mm using a punch. The punched positive electrode mixture layer was compression molded using a hand press to obtain a positive electrode for a lithium secondary battery.
- All the electrodes were produced so as to fall within the above coating amount and thickness range, and the electrode structure was kept constant.
- the prepared electrode was dried at 120 ° C. In addition, in order to remove the influence of moisture, all the operations were done in the dry room.
- a three-pole model cell in which the battery was simply reproduced was manufactured in the following procedure.
- the test electrode punched into a diameter of 15 mm, an aluminum current collector, metallic lithium for a counter electrode, and metallic lithium for a reference electrode were laminated via a separator impregnated with an electrolytic solution.
- Electrolyte solution dissolves LiPF 6 in the solvent which mixed ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in the ratio of 1: 2 (volume ratio), and makes it 1 mol / l, 0.8 mass in this solution % Vinylene carbonate (VC) was used.
- This laminate was sandwiched between two SUS end plates and tightened with a bolt. This was placed in a glass cell to make a tripolar model cell.
- composition and production conditions of the positive electrode active material of Example 1-1 are shown in Table 1 described later.
- Test evaluation (A) XRD measurement (crystal phase identification, average primary particle size evaluation) Powder X-ray diffraction measurement (XRD measurement) was performed according to the following procedure, and the identification of the crystal phase of the carbon-coated positive electrode active material obtained above and the average primary particle diameter were calculated.
- a powder X-ray diffraction measuring device manufactured by Rigaku Corporation, model: RINT-2000 was used.
- the crystal phase was identified about the diffraction pattern obtained by measuring using ICSD (Inorganic Crystal Structure Database).
- the integral width ⁇ i was determined when a standard Si sample (manufactured by NIST, product name: 640 d) was measured under the same apparatus and under the same conditions, and the integral width ⁇ was defined by the following (formula 2).
- the crystallite diameter D is determined using the Scherrer equation shown in the following (formula 3), and this is taken as the average primary particle diameter.
- ⁇ is the wavelength of the X-ray source
- ⁇ is the reflection angle
- K is the Scherrer constant
- K 4/3.
- FIG. 2A is an appearance photograph (SEM observation image) of the positive electrode active material for a lithium secondary battery according to the present invention before the carbon coating removal treatment.
- FIG. 2B is an external appearance photograph (SEM observation image) after heating the positive electrode active material for lithium secondary batteries of FIG. 2A in air at 450 ° C. for 1 hour. As shown in FIGS. 2A and 2B, it can be seen that the appearance of the particles has not changed before and after the carbon coating removal treatment.
- the measured value (a) of the specific surface area was measured using an automatic specific surface area measuring device (manufactured by Nippon Bell Co., Ltd., model: BELSORP-mini). Moreover, the calculated value (b) of the specific surface area was calculated using the value of the average primary particle diameter described above. The obtained values of (a) and (b) were substituted into (Expression 1) to obtain the roughness factor.
- the primary particle diameter calculated according to the above definition is a primary particle diameter measured by X-ray diffraction and evaluated from the overall averaged crystallite diameter, so an aggregate including a large number of small crystallites
- the primary particle diameter is calculated to be smaller than usual, and it is not consistent with the case where individual particles are observed and measured with an electron microscope or the like.
- the particle diameter being calculated to be smaller, when the crystallite becomes smaller than the effect that the denominator (b) of the formula shown in (Expression 1) becomes larger, the measured value of the specific surface area of the positive electrode active material is The effect of increasing the molecule (a) increases, and the roughness factor increases.
- Carbon Content Measurement The carbon content of the positive electrode active material was measured using a high frequency combustion-infrared absorption method. The carbon content is also shown in Table 3.
- Rate characteristic evaluation After repeating the above-mentioned charge / discharge test for 3 cycles, rate characteristics were evaluated under the following conditions. The capacity of the model cell subjected to constant current charging and constant voltage charging in the same manner as in the capacity measurement was subjected to constant current discharge at a current value of 5 mA as a rate characteristic. The results are shown in Table 3.
- LiFe 0.2 Mn 0.8 PO 4 was obtained by the same method as Example 1-1 except that the pre-baking temperature was 600 ° C.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, energy density measurement, and SEM observation were also performed similarly.
- Table 1 shows the composition and manufacturing conditions of the positive electrode active material
- Table 3 shows the measurement results. An appearance photograph of the positive electrode active material powder of Example 1-2 is shown in FIG. 3B.
- LiMnPO 4 was prepared in the same manner as in Example 1-1 except that manganese acetate tetrahydrate (Mn (CH 3 COO) 2 .4H 2 O) was used as the metal source, and the total amount of transition metals was Mn. Obtained.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 1 shows the composition and manufacturing conditions of the positive electrode active material, and Table 3 shows the measurement results.
- LiMnPO 4 was obtained by the same method as Example 1-3 except that the pre-baking temperature was 600 ° C.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 1 shows the composition and manufacturing conditions of the positive electrode active material, and Table 3 shows the measurement results.
- LiFePO 4 was obtained by the same method as in Example 1-1 except that only citrate iron (FeC 6 H 5 O 7 ⁇ n H 2 O) was used as the metal source, and the total amount of transition metals was Fe.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 1 shows the composition and manufacturing conditions of the positive electrode active material, and Table 3 shows the measurement results.
- LiFePO 4 was obtained by the same method as Example 1-5 except that the pre-baking temperature was 600 ° C.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 1 shows the composition and manufacturing conditions of the positive electrode active material, and Table 3 shows the measurement results.
- LiFe 0.2 Mn 0.8 PO 4 was obtained in the same manner as in Example 1-1 except that the pre-baking temperature was changed to 380 ° C. XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, energy density measurement and SEM observation were also performed similarly. Table 2 shows the composition and manufacturing conditions of the positive electrode active material, and Table 4 shows the measurement results. An appearance photograph of the positive electrode active material powder of Reference Example 1-1 is shown in FIG. 3C.
- reference examples refer to temporary firing in an oxidizing atmosphere and main firing in a non-oxidizing atmosphere as in the present invention, and a positive electrode active material manufactured by a solid phase method.
- the pre-baking temperature is lower than the crystallization temperature of olivine. Therefore, the reference example is described in order to show the importance of the roughness factor and the calcination temperature of the present invention although not known per se.
- Lithium hydroxide (LiOH), phosphoric acid (H 3 PO 4 ), manganese sulfate (MnSO 4 ), and iron sulfate (FeSO 4 ) were used as raw materials.
- an aqueous solution of lithium hydroxide was dropped therein to obtain a suspension containing a precipitate.
- the obtained suspension was subjected to nitrogen bubbling and sealed in a pressure resistant vessel while replacing with nitrogen.
- the pressure container was heated at 170 ° C. for 5 hours while rotating and stirring, and the obtained precipitate was filtered and washed to obtain LiMn 0.8 Fe 0.2 PO 4 .
- Sucrose was added to the obtained LiMn 0.8 Fe 0.2 PO 4 at a mass ratio of 7% by mass. This was mixed for 2 hours using a wet ball mill. Next, it was fired using an atmosphere-controllable tubular furnace and subjected to carbon coating.
- the firing atmosphere was Ar atmosphere, the firing temperature was 700 ° C., and the firing time was 3 hours.
- Table 2 shows the composition and manufacturing conditions of the positive electrode active material
- Table 4 shows the measurement results. Further, an appearance photograph of the positive electrode active material powder of Comparative Example 1-1 is shown in FIG. 3D.
- LiMnPO 4 was produced in the same manner as in Example 1-3 except that the pre-baking temperature was changed to 380 ° C.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 2 shows the composition and manufacturing conditions of the positive electrode active material, and Table 4 shows the measurement results.
- LiFePO 4 was produced in the same manner as in Example 1-5 except that the pre-baking temperature was changed to 380 ° C.
- the XRD measurement, specific surface area measurement, charge / discharge test, rate characteristic evaluation, and energy density measurement were performed in the same manner.
- Table 2 shows the composition and manufacturing conditions of the positive electrode active material, and Table 4 shows the measurement results.
- the characteristics of the positive electrode active material having an olivine type structure differ depending on the molar ratio of Mn to Fe in M. Generally, the larger the amount of Fe, the better the capacity and rate characteristics, but the lower the average voltage, the lower the energy density. Therefore, the examples, reference examples, and comparative examples are compared for each composition of the positive electrode active material.
- the positive electrode active material is LiMnPO 4 and Examples 1-3 and 1-4 are compared with Reference Example 1-2 and Comparative Example 1-2, respectively, the Example has the same capacity, rate characteristics, and energy density. All three items are higher than the comparative example.
- Example 1-7 improvement in energy density and rate characteristics was observed as compared with Example 1 in which Mg was not added.
- the addition of Mg may improve the crystallinity and facilitate the absorption and release of Li.
- the roughness factor of the example, the reference example and the comparative example is compared, in all the examples, it exceeds 1 whereas in the reference example and the comparative example, it is all 1 or less. If the particle diameter is a true sphere and it is completely dispersed, the roughness factor will be 1, but it will increase or decrease due to several factors. The cause of the increase is the increase in the particle surface roughness, which is high in the example because the production method is used to increase the particle surface roughness. Further, in the examples, the firing at the crystallization temperature or higher prevents the generation of unreacted substances and maintains a good dispersed state even after the main firing, so the specific surface area is high.
- the positive electrode active material is manufactured by a hydrothermal method, and since the particle surface is smooth and thus lower than the example, the roughness factor is small, and the positive electrode active material and the electrolyte are It is believed that the battery's capacity, rate characteristics and energy density have been reduced.
- the positive electrode active material (FIGS. 3A and 3B) according to the present invention has a larger surface roughness than the conventional positive electrode active material (FIGS. 3C and 3D).
- the positive electrode active material for a lithium secondary battery according to the present invention uses a highly safe polyanion-based compound and has a higher capacity than a lithium secondary battery using a conventional polyanion-based positive electrode active material. It has been shown that a positive electrode active material for a lithium secondary battery can be provided that achieves high rate characteristics and high energy density, and that the smoothness and uniformity of the electrode are good.
- Example 1 the positive electrode active material having a primary particle shape has been described.
- the positive electrode active material is often used as secondary particles for reasons such as facilitation of electrode production.
- Example 2 a method of producing a secondary particle-formed positive electrode active material and measurement results of characteristics (capacity and rate characteristics) of an electrode produced using the produced positive electrode active material will be described. In particular, the relationship between the secondary particle diameter and the corresponding electrode will be described.
- FIG. 5 shows a manufacturing flow.
- Step S100 The materials of the positive electrode active material are mixed.
- Step S200 The mixed materials are calcined temporarily to obtain a calcined body.
- Step S300 A carbon source is mixed with the temporary fired body.
- Step S400 Secondaryize the slurry having the mixed carbon source.
- Step S500 The pre-sintered body and the carbon source mixed are subjected to main firing.
- Example 2-1 (I) Mixing of Raw Materials: The same materials and specifications as those described above (Fabrication of lithium secondary battery of Example 1-1). (Ii) Pre-baking: The raw material powder was temporarily fired using a box-type electric furnace. The firing atmosphere was air, the firing temperature was 440 ° C., and the firing time was 10 hours. (Iii) Mixing and coating with carbon sources: 7% by mass of sucrose was added to the calcined body as a carbon source and a particle size control agent. This was ground and mixed for 2 hours using a ball mill. (Iv) Secondary particle formation: In the ball mill process, pure water was used as a dispersion medium. After the ball mill mixing, the slurry was spray-dried at an air spray pressure of 0.2 MPa using a spray dryer equipped with a 4-fluid nozzle to perform secondary particle formation.
- FIG. 4 shows an SEM photograph of spherical secondary particles according to the present invention as an example.
- spray drying is the method of supplying the slurry which was micronized in the drying chamber, and drying it to obtain spherical particles.
- the mean particle size of the spherical secondary particles is less than 5 ⁇ m, the packing density tends to be low when electroded.
- the average particle size is more than 20 ⁇ m, the secondary particles become large with respect to the electrode thickness, and the electrode density decreases.
- the electrode density is calculated by dividing the coating amount (mg / cm 2 ) by the electrode thickness ( ⁇ m).
- An electrode (positive electrode) was produced using the produced active material, and the characteristics of the electrode, that is, the capacity and rate characteristics were measured.
- the method of producing the electrode is the same as the method described in the section of Example 1 described above.
- rate characteristics were evaluated under the following conditions.
- the capacity of the model cell subjected to constant current charging and constant voltage charging in the same manner as in the capacity measurement was subjected to constant current discharge at a current value of 5 mA as a rate characteristic.
- all the tests were performed at room temperature (25 degreeC).
- Example 2-2 A LiFe 0.2 Mn 0.8 PO 4 was obtained in the same manner as in Example 2-1 except that the pre-baking temperature was 600 ° C. The capacity and rate characteristics were also measured in the same manner.
- Example 2-3 To the calcined body, 7 parts by weight of sucrose was added per 100 parts by weight as a carbon source and a particle size control agent, and pulverized and mixed for 2 hours using a ball mill. After the ball mill mixing, a slurry was manufactured using an evaporator in the same manner as in Example 2-1 except that the slurry was dried to obtain LiFe 0.2 Mn 0.8 PO 4 . The capacity and rate characteristics were also measured in the same manner.
- the slurry was prepared using a wet ball mill and was spray-dried at an air spray pressure of 0.2 MPa using a spray dryer equipped with a four-fluid nozzle to form secondary particles.
- Carbon-coated LiFe 0.2 Mn 0.8 PO 4 was obtained by the above steps.
- the capacity and rate characteristics were measured in the same manner as in Example 2-1.
- Example 2-4 A lithium Fe 0.2 Mn 0.8 PO 4 was produced in the same manner as in Example 2-1 except that the air spray pressure was 1.0 MPa. The capacity and rate characteristics were also measured in the same manner.
- Example 2-5 A LiFe 0.2 Mn 0.8 PO 4 was produced in the same manner as in Example 2-1 except that a disk spray dryer was used for slurry drying after ball mill mixing. The capacity and rate characteristics were also measured in the same manner.
- the rate characteristic it is understood from Table 5 that the examples 2-1 and 12 have higher rate characteristics than any of the comparative examples 2-1 and 2-2. Therefore, it can be seen that the embodiment is higher in both capacity and rate characteristics than the comparative example, and in particular, the rate characteristics are higher.
- the roughness factors of the primary particles of Examples 2-1 and 2-2 and Comparative Examples 2-1 and 2-2 are all over 1 in Examples, In the comparative example, it is all 1 or less.
- the roughness factor of the primary particles is 1, but increases or decreases depending on several factors.
- the cause of the increase is the increase of the particle surface roughness, and in the example, the production method of increasing the particle surface roughness is used, and the roughness factor of the primary particles is high.
- the roughness factor of the primary particle is lower than that of the example.
- Comparative Example 2-2 is produced by a hydrothermal synthesis method, and the particles have a smooth surface, and the roughness factor of the primary particles is lowered. That is, if the particle size is the same, it is considered that the specific surface area is lowered and the activity is lowered. On the other hand, in the examples, the firing at the crystallization temperature or higher prevents the generation of unreacted substances and maintains a good dispersed state even after the main firing, so the specific surface area is high. That is, it can be seen that the roughness factor of primary particles obtained from the values of particle diameter and specific surface area greatly affects the characteristics.
- Example 2-1 When Example 2-1 is compared with Examples 2-3 and 2-4, the average particle diameter of the secondary particles in Example 2-1 is 12 ⁇ m, and it is 3 ⁇ m in Example 2-3. In 2-4, it shows 25 ⁇ m. Then, when the relationship between the particle size and the electrical characteristics is seen, the capacity per volume (mAh / cc) in Example 2-1 is 285, whereas in Examples 2-3, 249 and 260, respectively. And low values.
- the value is as low as 1.63 and 1.68 in Examples 2-3 and 2-4, while it is 1.83 in Example 2-1. It shows.
- the average secondary particle size affects the electrode density and the volume per volume.
- the average secondary particle diameter is less than 5 ⁇ m or more than 20 ⁇ m, it is understood that the electrode density decreases and the capacity per volume of the positive electrode active material decreases.
- Example 2-1 and Example 2-3 add 7 parts by weight of sucrose to 100 parts by weight as a carbon source and a particle size control agent to the calcined body, and after mixing in a ball mill, the slurry is It is the difference between drying with a spray dryer to obtain secondary particles or drying using an evaporator to obtain secondary particles.
- Example 2-1 Comparing Example 2-1 with Example 2-5, with respect to the shape of the positive electrode active material, while spherical secondary particles were obtained in Example 2-1, Example 2-5 is amorphous. Secondary particles were obtained.
- Example 2-1 the electrode density, capacity per volume, and rate characteristics of Example 2-1 are 1.83, 285 and 142, respectively, while Example 2-5 includes 1.45 and 228, respectively. Since the value is 137, in Example 2-1, the electrode density, the capacity per volume, and the rate characteristics are higher. The electrode density is improved by granulating the spherical secondary particles by spray drying. On the other hand, the one which is not granulated by spray drying is difficult to increase the electrode density. The electrode characteristics were also better when granulated by spray drying.
- the electrode density of the positive electrode is 1.8 g / cm 3 or more, the capacity value per weight is 150 Ah / kg or more, and the rate characteristic is 140 Ah / kg or more. Positive electrode was obtained.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
炭素で被覆されたポリアニオン系化合物粒子を含むリチウム二次電池用正極活物質であって、
前記ポリアニオン系化合物は下記(化学式1)で表わされる構造を有し、
前記ポリアニオン系化合物の下記(式1)で表わされるラフネスファクターが1~2であり、
前記ポリアニオン系化合物の平均一次粒子径が10~150nmであることを特徴とするリチウム二次電池用正極活物質を提供する。
LixMAyOz・・・・(化学式1)
(ただし、Mは少なくとも一種の遷移金属元素を含み、Aは酸素Oと結合してアニオンを形成する典型元素であり、0<x≦2、1≦y≦2、3≦z≦7である。)
LiMPO4 ・・・・(化学式2)
(ただし、MはFe、Mn、Co及びNiの内の少なくとも1種である。)
(2)前記オリビン型構造を有するポリアニオン系化合物中のMはMnとFeを含み、Mを占めるFeの割合が、モル比で0mol%超、50mol%以下である。
前述したように、本発明に係るリチウム二次電池用正極活物質は、炭素で被覆されたポリアニオン系化合物粒子を含むリチウム二次電池用正極活物質であって、該ポリアニオン系化合物粒子は、前記(化学式1)で表わされる構造を有する。
本発明のリチウム二次電池用正極活物質の製造方法について説明する。本発明は、オリビン型構造を有する化合物を初めとした、粒子径を200nm以下にして低抵抗化して使用することが必要な正極活物質を対象としている。粒子径が200nm以下の微粒子では凝集が起きやすく、それにより比表面積が低下し、ラフネスファクターが低下しやすい。
そのため、ラフネスファクターを大きくするためには、活物質粒子の表面粗さを向上させると共に、凝集、焼結を防ぐ製造方法を行う必要がある。
本発明による正極活物質の製造フローは、図5に示す。
本発明のリチウム二次電池用正極活物質は、結晶化温度以上でかつ結晶化温度を大幅に超えない温度で仮焼成を行うことにより、微結晶を得ることができる。後述する本焼成において、この微結晶を多数含む一次粒子を得ることができる。このような形態の一次粒子は、表面の凹凸が大きく、ラフネスファクターが大きくなる。このとき、一次粒子を構成する微結晶の大きさは、原料の粒子径などに依存する。該微結晶を小さくするほど表面粗さは大きくなるので、正極活物質の原料の粒子径は、可能な限り小さい(例えば、1μm以下)ことが望ましい。また、原料を均一に混合していない場合、仮焼成時に生成する結晶が粗大化したり、異相(ポリアニオン系化合物以外の化合物、例えばMn又はFeの酸化物、MnP2O7など)が発生したりするため、より均一に混合されていることが望ましい。
仮焼成温度は、ポリアニオン系化合物の結晶化温度以上で、かつ結晶化温度を大きく超えないことが必要である。結晶化温度より低いと、仮焼成で多量の未反応物が生じる。これら未反応物は後述する本焼成において活物質相に転移するが、その際に複数の粒子同士を結合してしまい、粒子の凝集、焼結を招く。粒子の凝集、焼結が起きると比表面積が低下し、反応性が下がる。また、仮焼成温度を上げていくことにより製造後の粒子径を大きくすることができるが、仮焼成温度があまり高すぎると粒子が粗大化して正極活部質の比表面積が減少し、正極活物質と電解質の反応面積が減少する。
特に、原料を、溶液状態を経て均一に混合した場合には、原料中に有機物が均一に混ざっているので、不活性雰囲気や還元雰囲気では有機物が結晶中に取り込まれやすい。
上記で得た仮焼成体は結晶性が低いので、結晶性向上のためには、より高温での焼成が必要である。しかし、単に高温で本焼成した場合、仮焼成で得られた微結晶同士が容易に結合して成長し、粒子が粗大化してしまう。そこで本焼成の前に、仮焼成体に炭素源となる有機物または炭素を混合し、被覆する。このように仮焼成で得られた微結晶の周囲に有機物や炭素を密着させて、微結晶を被覆することにより、本焼成時に結晶同士が結合して結晶が成長することを抑えることができる。炭素源としては、アセチレンブラック、黒鉛、糖、有機酸、ピッチなどが好適である。この中でも、仮焼成体表面への密着性を考慮すると糖、有機酸、ピッチが特に好ましい。
本焼成では、上記で仮焼成体に被覆した炭素源を炭化して正極活物質の導電性を向上させると共に、活物質粒子の結晶性向上もしくは結晶化を行う。本焼成では、有機物(炭素源)の炭化を行い、金属元素の酸化を防止する必要があるため、不活性雰囲気または還元雰囲気で行う。本焼成温度は有機物を炭化するために600℃以上が望ましい。また本焼成は、正極活物質の熱分解が起きる温度以下で行うことが望ましい。オリビン型構造を有する化合物においては、望ましい本焼成温度の範囲は、600~850℃である。600℃以上ならば、炭素源を炭化して導電性を付与することができる。850℃以下ならば、オリビン型構造を有する化合物が分解を起こさない。さらに望ましくは、700~750℃である。この温度範囲では、炭素の導電性を十分に向上できると共に、炭素とオリビン型構造を有する化合物の反応による不純物の生成を抑えることができる。
本発明のリチウム二次電池用正極は、上述した本発明の正極活物質と結着剤を含む正極合材が、集電体上に形成された構成である。正極合剤には、電子伝導性を補うために、必要に応じて導電助材が添加されていてもよい。結着剤、導電助材、集電体の材料には特段の制限はなく、従来のものを用いることができる。
リチウム二次電池の構成について説明する。図1は、発明を適用したリチウム二次電池の1例を示す半断面模式図である。図1に示したように、正極10および負極6は、これらが直接接触しないようにセパレータ7を挟み込んだ状態で惓回されて、電極群を形成している。なお、電極群の構造は、円筒状、扁平状などの形状の捲回に限定されるものではなく、短冊状電極を積層したものであってもよい。
(i)原料の混合
金属源として、クエン酸鉄(FeC6H5O7・nH2O)と酢酸マンガン四水和物(Mn(CH3COO)2・4H2O)を用い、FeとMnが2:8となるように秤量し、これを純水中に溶解した。これにキレート剤としてクエン酸一水和物(C6H8O7・H2O)を添加した。キレート剤の量は、クエン酸イオンが金属イオンの合計量に対し80mol%添加となるよう、他のクエン酸塩の添加量に応じて調整した。キレート剤を添加すると、クエン酸イオンが金属イオン周囲に配位することにより、沈殿の生成を抑え、均一に溶解した原料溶液を得ることができる。
上記で得た原料粉を、箱型電気炉を用いて仮焼成した。焼成雰囲気は空気とし、焼成温度は440℃で、焼成時間は10時間とした。
上記で得た仮焼成体に対し、炭素源及び粒径制御剤として、質量比7質量%の割合でスクロースを添加し、ボールミルを用いて2時間粉砕、混合した。
次に、雰囲気制御可能な管状炉を用いて、本焼成を行った。焼成雰囲気はアルゴン(Ar)雰囲気とし、焼成温度は700℃で、焼成時間は10時間とした。
電極の組成は、正極活物質、導電材、バインダの質量比が82.5:10:7.5となるようにした。
(試験評価)
(a)XRD測定(結晶相同定、平均一次粒子径評価)
以下の手順で粉末X線回折測定(XRD測定)を行い、上記で得た、炭素被覆した正極活物質の結晶相の同定と平均一次粒子径を算出した。測定装置には、粉末X線回折測定装置(株式会社リガク製、型式:RINT‐2000)を用いた。測定条件は、集中法で、X線としてCuKα線を用い、X線出力を40kV×40mAとし、走査範囲を2θ=15~120degとし、発散スリットをDS=0.5deg、ソーラースリットをSS=0.5deg、受光スリットをRS=0.3mmとし、ステップ幅0.03°、1ステップ当たりの測定時間が15秒とした。 測定して得た回折パターンについて、ICSD(Inorganic Crystal Structure Database)を用いて結晶相を同定した。
炭素など比表面積が大きい物質が付着することにより、正極活物質本来の比表面積より高い値が測定されてしまうことがある。さらには、炭素被覆量によって比表面積が大きく変化し、比表面積が活物質粒子自体の特性を反映しなくなってしまう。そのため、本発明では、正極活物質粒子の比表面積の実測値(a)を測定する際、炭素の表面被覆を除去した粒子を用いた。除去方法は限定されないが、粒子表面の形状を変化させてはならない。
例えば炭素被覆の場合、空気中、450℃で1時間加熱することにより、粒子表面の形状に影響を与えない上で炭素被覆を除去できる。
正極活物質の炭素含有量は、高周波燃焼‐赤外線吸収法を用いて測定した。炭素含有量を表3に併記する。
上記で用意した三極式モデルセルについて、以下の充放電試験を実施し、初期容量を評価した。なお試験はAr雰囲気のグローブボックス内で、室温(25℃)で行った。電流値を0.1mAとして4.5Vまで定電流充電を行い、4.5Vに達した後は、電流値が0.03mAに減衰するまで定電圧充電を行った。その後、2Vまで0.1mAの定電流で放電し、その際の放電容量を容量とした。結果を表3に併記する。
上記の充放電試験を3サイクル繰り返した後、以下の条件でレート特性を評価した。容量測定と同様に定電流充電と定電圧充電を行ったモデルセルを、5mAの電流値で定電流放電したときの容量をレート特性とした。結果を表3に併記する。
上記で用意した三極式モデルセルについて、放電曲線(電池電圧の容量依存性)を測定し、これを数値積分してエネル密度を算出した。結果を表3に併記する。
正極活物質の試料表面をSEM測定によって観察した。観察には、走査電子顕微鏡(株式会社日立ハイテクノロジーズ製、型式:S-4300)を用いた。実施例1-1の正極活物質粉末の外観写真を図3Aに示す。
仮焼成温度を600℃とした以外は、実施例1-1と同様の方法により、LiFe0.2Mn0.8PO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定、SEM観察も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。また、実施例1-2の正極活物質粉末の外観写真を図3Bに示す。
金属源として、酢酸マンガン四水和物(Mn(CH3COO)2・4H2O)を用い、遷移金属を全量Mnとした以外は、実施例1-1と同様の方法により、LiMnPO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。
仮焼成温度を600℃とした以外は、実施例1-3と同様の方法により、LiMnPO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。
金属源として、クエン酸鉄(FeC6H5O7・nH2O)のみを用い、遷移金属を全量Feとした以外は、実施例1-1と同様の方法により、LiFePO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。
仮焼成温度を600℃とした以外は、実施例1-5と同様の方法により、LiFePO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。
金属源として、酢酸マンガン四水和物(Mn(CH3COO)2・4H2O)、クエン酸鉄(FeC6H5O7・nH2O)、水酸化マグネシウム(Mg(OH)2)を用いた以外は、実施例1-1と同様の方法により、LiMn0.77Fe0.2Mg0.03PO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表1に、測定結果を表3に併記する。
仮焼成温度を380℃にした以外は、実施例1-1と同様の方法により、LiFe0.2Mn0.8PO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定及びSEM観察も同様に行った。正極活物質の組成と製造条件を表2に、測定結果を表4に示す。また、参考例1-1の正極活物質粉末の外観写真を図3Cに示す。なお、本明細書において参考例とは本発明と同様に酸化雰囲気下での仮焼成及び非酸化雰囲気下での本焼成を行っており、固相法により正極活物質を製造したものであるが、仮焼成温度がオリビンの結晶化温度より低い温度である。したがって参考例はそれ自体公知ではないが本発明のラフネスファクター及び仮焼成温度の重要性を示すために記載した。
水熱合成法を実施した。原料に水酸化リチウム(LiOH)、リン酸(H3PO4)、硫酸マンガン(MnSO4)、硫酸鉄(FeSO4)を用いた。モル比でLi:PO4:Mn:Fe=3:1:0.8:0.2となるように原料を秤量した。硫酸マンガン、硫酸鉄、リン酸を純水に溶解させた溶液を攪拌しながら、その中に水酸化リチウム水溶液を滴下し、沈殿を含む懸濁液を得た。
仮焼成温度を380℃にした以外は、実施例1-3と同様に製造し、LiMnPO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表2に、測定結果を表4に示す。
原料に水酸化リチウム、リン酸、硫酸マンガンを用い、モル比でLi:PO4:Mn=3:1:1となるように原料を秤量し用いた以外は比較例1-1と同様に製造し、LiMnPO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表2に、測定結果を表4に示す。
仮焼成温度を380℃にした以外は、実施例1-5と同様に製造し、LiFePO4を得た。XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表2に、測定結果を表4に示す。
水酸化リチウム、リン酸、硫酸鉄を用い、モル比でLi:PO4:Fe=3:1:1となるように原料を秤量し用いた以外は比較例1-1と同様に製造し、LiFePO4を得た。
XRD測定、比表面積測定、充放電試験、レート特性評価、エネルギー密度測定も同様に行った。正極活物質の組成と製造条件を表2に、測定結果を表4に示す。
以下に、本発明による正極活物質の製造方法を説明する。図5に製造フローを示す。
ステップS100:正極活物質の原料を混合する。
ステップS200:混合した原料を仮焼成し、仮焼成体を得る。
ステップS300:仮焼成体に炭素源を混合する。
ステップS400:混合した炭素源を有するスラリーを二次粒子化する。
ステップS500:混合した仮焼成体及び炭素源を本焼成する。
(i)原料の混合:上述した(実施例1-1のリチウム二次電池の作製)と同様の材料及び仕様である。
(ii)仮焼成:
原料粉に対し、箱型電気炉を用いて仮焼成した。焼成雰囲気は空気とし、焼成温度は440℃で、焼成時間は10時間とした。
(iii)炭素源との混合及び被覆:
この仮焼成体に対し、炭素源及び粒径制御剤として、7質量%のスクロースを添加した。これを、ボールミルを用いて2時間粉砕、混合した。
(iv)二次粒子化:
ボールミル工程では、分散媒として純水を用いた。ボールミル混合後、スラリーを4流体ノズルを備えたスプレードライヤを用いてエア噴霧圧0.2MPaで噴霧乾燥し、二次粒子化を行った。
(v)本焼成:
次に、雰囲気制御可能な管状炉を用いて、本焼成を行った。焼成雰囲気はAr雰囲気とし、焼成温度は700℃で、焼成時間は10時間とした。
以上の工程により、オリビンLiFe0.2Mn0.8PO4を得た。
製造した活物質を用いて電極(正極)を作製し、電極の特性、すなわち容量とレート特性を測定した。電極の作製方法は、上述した実施例1の項で説明した方法と同様である。
容量とレート特性の測定試験は、Ar雰囲気のグローブボックスで行った。容量測定では、モデルセルに対して、電流値を0.1mAとして4.5Vまで定電流充電を行い、4.5Vに達した後は、電流値が0.03mAに減衰するまで定電圧充電を行った。その後、2Vまで0.1mAの定電流で放電し、その際の放電容量を容量とした。容量は正極活物質の重量当たり、体積当たりをそれぞれ算出した。
仮焼成温度を600℃とした以外は、実施例2-1と同様に製造し、LiFe0.2Mn0.8PO4を得た。容量、レート特性の測定も同様に行った。
仮焼成体に対し、炭素源及び粒径制御剤として、100重量部に対して7重量部のスクロースを添加し、ボールミルを用いて2時間粉砕、混合した。ボールミル混合後、スラリーをエバポレーターを用いて乾燥させた以外は実施例2-1と同様に製造し、LiFe0.2Mn0.8PO4を得た。容量、レート特性の測定も同様に行った。
仮焼成温度を380℃にした以外は、実施例2-1と同様に製造し、LiFe0.2Mn0.8PO4を得た。容量、レート特性の測定も同様に行った。
水熱合成法を実施した。原料に水酸化リチウム、リン酸、硫酸マンガン、硫酸鉄を用いた。モル比でLi:PO4:Mn:Fe=3:1:0.8:0.2となるように原料を秤量した。硫酸マンガン、硫酸鉄、リン酸を純水に溶解させた溶液を攪拌しながら、その中に水酸化リチウム水溶液を滴下し、沈殿を含む懸濁液を得た。得られた懸濁液に窒素バブリングを行い、耐圧容器に窒素置換しながら封入した。耐圧容器を回転攪拌しながら170℃で5時間加熱し、得られた沈殿物をろ過、洗浄することによりLiMn0.8Fe0.2PO4を得た。
エア噴霧圧を1.0MPaとした以外は、実施例2-1と同様に製造し、LiFe0.2Mn0.8PO4を得た。容量、レート特性の測定も同様に行った。
ボールミル混合後のスラリー乾燥にディスク式スプレードライヤを用いた以外は、実施例2-1と同様に製造し、LiFe0.2Mn0.8PO4を得た。容量、レート特性の測定も同様に行った。
上述した実施例2-1~2-5、比較例2-1、2-2のそれぞれについて、本焼成して得られたLiFe0.2Mn0.8PO4の一次粒子の粒子径、比表面積、ラフネスファクター、二次粒子形状、二次粒子の平均粒径、電極密度、容量、レート特性を示したものを表5に示す。
比較例2-1は、仮焼成温度が結晶化温度よりも低く未反応物が本焼成前に残っているため、粒子同士の凝集、焼結を招き、粒子径が小さいように見えても比表面積が低くなり、活性が低下していると考えられる。
すなわち、粒子径と比表面積の値から求められる一次粒子のラフネスファクターが特性に大きな影響を与えることがわかる。
Claims (15)
- 請求項1に記載のリチウム二次電池用正極活物質において、
前記ポリアニオン系化合物は、下記(化学式2)で表わされるオリビン型構造を有することを特徴とするリチウム二次電池用正極活物質。
LiMPO4 ・・・・(化学式2)
(ただし、MはFe、Mn、Co及びNiの内の少なくとも1種である。) - 請求項2に記載のリチウム二次電池用正極活物質において、
前記オリビン型構造を有するポリアニオン系化合物中のMはMnとFeを含み、Mに占めるFeの割合が、モル比で0mol%超、50mol%以下であることを特徴とするリチウム二次電池用正極活物質。 - 請求項1ないし3のいずれか1項に記載のリチウム二次電池用正極活物質において、
前記炭素の含有量が2~5質量%であることを特徴とするリチウム二次電池用正極活物質。 - 請求項1に記載のリチウム二次電池用正極活物質において、
前記一次粒子の平均粒径は、10nm以上100nm以下の範囲であることを特徴とするリチウム二次電池用正極活物質。 - 請求項1に記載のリチウム二次電池用正極活物質において、
前記正極活物質は複数の一次粒子が凝集した二次粒子よりなることを特徴とするリチウム二次電池用正極活物質。 - 請求項6に記載のリチウム二次電池用正極活物質において、
前記二次粒子径の平均粒径は、5~20μmの範囲であることを特徴とするリチウム二次電池用正極活物質。 - 正極活物質を含む正極合剤と、正極集電体とを有するリチウム二次電池用正極であって、前記正極活物質が、請求項1ないし7のいずれか1項に記載のリチウム二次電池用正極活物質であることを特徴とするリチウム二次電池用正極。
- 正極と、負極と、前記正極と前記負極とを仕切るセパレータと、電解質を備えたリチウム二次電池であって、前記正極は、請求項8に記載のリチウム二次電池用正極であることを特徴とするリチウム二次電池。
- 前記正極の電極密度が1.8g/cm3以上であって、重量当たりの容量値が150Ah/kg以上で、レート特性が140Ah/kg以上の特性を備えたことを特徴とする請求項7に記載のリチウム二次電池。
- 化学式LiMPO4(Mは、Fe、Mn、Co、及びNiのうち少なくとも1つを含む)で表されるリチウム二次電池用正極活物質の製造方法であって、
金属源となる遷移金属化合物と、リン化合物とを含むを混合する工程と、
混合した前記原料を仮焼成する工程と、
前記仮焼成する工程により得た仮焼成体に炭素源を混合する工程と、
炭素源が混合された前記仮焼成体を本焼成する工程とを有し、
前記仮焼成における仮焼成温度は、前記正極活物質の結晶化温度以上で、前記結晶化温度に200℃を加えた温度以下である、
ことを特徴とするリチウム二次電池用正極活物質の製造方法。 - 請求項11に記載のリチウム二次電池用正極活物質の製造方法において、
前記仮焼成工程の後、前記本焼成の工程前に、前記仮焼成体を二次粒子化する工程を備えることを特徴とするリチウム二次電池用正極活物質の製造方法。 - 請求項11に記載のリチウム二次電池用正極活物質の製造方法において、
前記仮焼成工程の仮焼成温度は、420℃~600℃であることを特徴とするリチウム二次電池用正極活物質の製造方法。 - 請求項11ないし13のいずれかに記載のリチウム二次電池用正極活物質の製造方法において、
前記本焼成工程の本焼成温度は、600~850℃であることを特徴とするリチウム二次電池用正極活物質の製造方法。 - 請求項11ないし13のいずれかに記載のリチウム二次電池用正極活物質の製造方法において、
前記仮焼成工程、前記本焼成工程は、固相法であることを特徴とするリチウム二次電池用正極活物質の製造方法。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/416,394 US20150188139A1 (en) | 2012-07-25 | 2013-07-25 | Positive Electrode Active Material for Lithium Secondary Batteries, Positive Electrode for Lithium Secondary Batteries Using Same, Lithium Secondary Battery, and Method for Producing Positive Electrode Active Material for Lithium Secondary Batteries |
CN201380039177.6A CN104584282A (zh) | 2012-07-25 | 2013-07-25 | 锂二次电池用正极活性物质、使用其的锂二次电池用正极及锂二次电池、以及锂二次电池用正极活性物质的制造方法 |
KR1020157001740A KR20150047477A (ko) | 2012-07-25 | 2013-07-25 | 리튬 이차전지용 양극 활물질, 그것을 사용한 리튬 이차전지용 양극 및 리튬 이차전지, 및 리튬 이차전지용 양극 활물질의 제조 방법 |
JP2014527021A JP6094584B2 (ja) | 2012-07-25 | 2013-07-25 | リチウム二次電池用正極活物質、それを用いたリチウム二次電池用正極及びリチウム二次電池、並びにリチウム二次電池用正極活物質の製造方法 |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2012-164802 | 2012-07-25 | ||
JP2012164802 | 2012-07-25 | ||
JP2013-013285 | 2013-01-28 | ||
JP2013013285 | 2013-01-28 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2014017617A1 true WO2014017617A1 (ja) | 2014-01-30 |
Family
ID=49997422
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2013/070251 WO2014017617A1 (ja) | 2012-07-25 | 2013-07-25 | リチウム二次電池用正極活物質、それを用いたリチウム二次電池用正極及びリチウム二次電池、並びにリチウム二次電池用正極活物質の製造方法 |
Country Status (5)
Country | Link |
---|---|
US (1) | US20150188139A1 (ja) |
JP (1) | JP6094584B2 (ja) |
KR (1) | KR20150047477A (ja) |
CN (1) | CN104584282A (ja) |
WO (1) | WO2014017617A1 (ja) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015195172A (ja) * | 2014-03-24 | 2015-11-05 | 株式会社デンソー | リチウムイオン二次電池 |
JP5876558B1 (ja) * | 2014-10-24 | 2016-03-02 | 太平洋セメント株式会社 | オリビン型リチウムイオン二次電池用正極活物質及びその製造方法 |
JP2016115524A (ja) * | 2014-12-15 | 2016-06-23 | 三井造船株式会社 | リチウムイオン二次電池用電極材料の製造方法 |
JP2016149296A (ja) * | 2015-02-13 | 2016-08-18 | 三井造船株式会社 | 炭素被覆リン酸鉄リチウムの製造方法 |
KR20160146974A (ko) * | 2014-07-09 | 2016-12-21 | 아사히 가세이 가부시키가이샤 | 비수계 리튬형 축전 소자 |
WO2017154592A1 (ja) * | 2016-03-07 | 2017-09-14 | 日立マクセル株式会社 | 非水電解液電池 |
JP6288341B1 (ja) * | 2017-03-30 | 2018-03-07 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP6288342B1 (ja) * | 2017-03-30 | 2018-03-07 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP2019040854A (ja) * | 2017-07-14 | 2019-03-14 | 泓辰電池材料有限公司Hcm Co., Ltd. | リチウム電池のカソードに用いるためのリン酸マンガン鉄リチウム系粒子、これを含有するリン酸マンガン鉄リチウム系粉末材料、およびその粉末材料を製造する方法 |
WO2021153110A1 (ja) | 2020-01-30 | 2021-08-05 | 東レ株式会社 | リチウムイオン二次電池用正極活物質およびリチウムイオン二次電池 |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015040747A1 (ja) * | 2013-09-20 | 2015-03-26 | 株式会社 東芝 | 非水電解質電池用電極、非水電解質電池及び電池パック |
JP7133435B2 (ja) * | 2018-02-20 | 2022-09-08 | Fdk株式会社 | 全固体電池 |
AU2020203801B1 (en) * | 2020-06-09 | 2021-03-11 | VSPC Ltd | Method for making lithium metal phosphates |
CN112582608B (zh) * | 2020-12-10 | 2021-10-01 | 散裂中子源科学中心 | 硅掺杂铁基聚阴离子化合物及其制备方法和应用 |
KR102593317B1 (ko) * | 2021-08-23 | 2023-10-23 | 컨템포러리 엠퍼렉스 테크놀로지 씨오., 리미티드 | 탄소 코팅 리튬인산철 캐소드 활물질, 이의 제조 방법, 이를 포함하는 캐소드 극판 및 리튬 이온 전지 |
CN117117153B (zh) * | 2023-10-16 | 2024-02-20 | 宁波容百新能源科技股份有限公司 | 一种正极材料及其制备方法、锂离子电池 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2011013243A1 (ja) * | 2009-07-31 | 2011-02-03 | トヨタ自動車株式会社 | 正極活物質及びその製造方法 |
JP2011076820A (ja) * | 2009-09-30 | 2011-04-14 | Hitachi Vehicle Energy Ltd | リチウム二次電池及びリチウム二次電池用正極 |
WO2011129224A1 (ja) * | 2010-04-13 | 2011-10-20 | 日本電気硝子株式会社 | リチウムイオン二次電池正極材料およびその製造方法 |
JP2011216477A (ja) * | 2010-03-19 | 2011-10-27 | Semiconductor Energy Lab Co Ltd | 蓄電装置及びその作製方法 |
JP2011249324A (ja) * | 2010-04-28 | 2011-12-08 | Semiconductor Energy Lab Co Ltd | 蓄電装置用正極活物質、蓄電装置、及び電気推進車両、並びに蓄電装置の作製方法 |
JP2012248378A (ja) * | 2011-05-27 | 2012-12-13 | Hitachi Metals Ltd | リチウム二次電池用正極活物質とその製造方法、リチウム二次電池用正極、及びリチウム二次電池 |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5268134B2 (ja) * | 2005-09-21 | 2013-08-21 | 関東電化工業株式会社 | 正極活物質の製造方法およびそれを用いた非水電解質電池 |
US7862987B2 (en) * | 2007-11-20 | 2011-01-04 | International Business Machines Corporation | Method for forming an electrical structure comprising multiple photosensitive materials |
-
2013
- 2013-07-25 KR KR1020157001740A patent/KR20150047477A/ko not_active Application Discontinuation
- 2013-07-25 CN CN201380039177.6A patent/CN104584282A/zh active Pending
- 2013-07-25 JP JP2014527021A patent/JP6094584B2/ja active Active
- 2013-07-25 WO PCT/JP2013/070251 patent/WO2014017617A1/ja active Application Filing
- 2013-07-25 US US14/416,394 patent/US20150188139A1/en not_active Abandoned
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2011013243A1 (ja) * | 2009-07-31 | 2011-02-03 | トヨタ自動車株式会社 | 正極活物質及びその製造方法 |
JP2011076820A (ja) * | 2009-09-30 | 2011-04-14 | Hitachi Vehicle Energy Ltd | リチウム二次電池及びリチウム二次電池用正極 |
JP2011216477A (ja) * | 2010-03-19 | 2011-10-27 | Semiconductor Energy Lab Co Ltd | 蓄電装置及びその作製方法 |
WO2011129224A1 (ja) * | 2010-04-13 | 2011-10-20 | 日本電気硝子株式会社 | リチウムイオン二次電池正極材料およびその製造方法 |
JP2011249324A (ja) * | 2010-04-28 | 2011-12-08 | Semiconductor Energy Lab Co Ltd | 蓄電装置用正極活物質、蓄電装置、及び電気推進車両、並びに蓄電装置の作製方法 |
JP2012248378A (ja) * | 2011-05-27 | 2012-12-13 | Hitachi Metals Ltd | リチウム二次電池用正極活物質とその製造方法、リチウム二次電池用正極、及びリチウム二次電池 |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015195172A (ja) * | 2014-03-24 | 2015-11-05 | 株式会社デンソー | リチウムイオン二次電池 |
KR101986001B1 (ko) * | 2014-07-09 | 2019-09-03 | 아사히 가세이 가부시키가이샤 | 비수계 리튬형 축전 소자 |
KR20160146974A (ko) * | 2014-07-09 | 2016-12-21 | 아사히 가세이 가부시키가이샤 | 비수계 리튬형 축전 소자 |
EP3168849A4 (en) * | 2014-07-09 | 2017-07-26 | Asahi Kasei Kabushiki Kaisha | Nonaqueous lithium-type power storage element |
US10446847B2 (en) | 2014-07-09 | 2019-10-15 | Asahi Kasei Kabushiki Kaisha | Nonaqueous lithium-type power storage element |
JP5876558B1 (ja) * | 2014-10-24 | 2016-03-02 | 太平洋セメント株式会社 | オリビン型リチウムイオン二次電池用正極活物質及びその製造方法 |
JP2016085815A (ja) * | 2014-10-24 | 2016-05-19 | 太平洋セメント株式会社 | オリビン型リチウムイオン二次電池用正極活物質及びその製造方法 |
JP2016115524A (ja) * | 2014-12-15 | 2016-06-23 | 三井造船株式会社 | リチウムイオン二次電池用電極材料の製造方法 |
JP2016149296A (ja) * | 2015-02-13 | 2016-08-18 | 三井造船株式会社 | 炭素被覆リン酸鉄リチウムの製造方法 |
WO2017154592A1 (ja) * | 2016-03-07 | 2017-09-14 | 日立マクセル株式会社 | 非水電解液電池 |
JP6288341B1 (ja) * | 2017-03-30 | 2018-03-07 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP2018170186A (ja) * | 2017-03-30 | 2018-11-01 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP2018170187A (ja) * | 2017-03-30 | 2018-11-01 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP6288342B1 (ja) * | 2017-03-30 | 2018-03-07 | 住友大阪セメント株式会社 | リチウムイオン二次電池用正極材料、及びリチウムイオン二次電池 |
JP2019040854A (ja) * | 2017-07-14 | 2019-03-14 | 泓辰電池材料有限公司Hcm Co., Ltd. | リチウム電池のカソードに用いるためのリン酸マンガン鉄リチウム系粒子、これを含有するリン酸マンガン鉄リチウム系粉末材料、およびその粉末材料を製造する方法 |
WO2021153110A1 (ja) | 2020-01-30 | 2021-08-05 | 東レ株式会社 | リチウムイオン二次電池用正極活物質およびリチウムイオン二次電池 |
KR20220134536A (ko) | 2020-01-30 | 2022-10-05 | 도레이 카부시키가이샤 | 리튬 이온 이차 전지용 정극 활물질 및 리튬 이온 이차 전지 |
Also Published As
Publication number | Publication date |
---|---|
JP6094584B2 (ja) | 2017-03-15 |
JPWO2014017617A1 (ja) | 2016-07-11 |
US20150188139A1 (en) | 2015-07-02 |
KR20150047477A (ko) | 2015-05-04 |
CN104584282A (zh) | 2015-04-29 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6094584B2 (ja) | リチウム二次電池用正極活物質、それを用いたリチウム二次電池用正極及びリチウム二次電池、並びにリチウム二次電池用正極活物質の製造方法 | |
JP5268134B2 (ja) | 正極活物質の製造方法およびそれを用いた非水電解質電池 | |
JP5736965B2 (ja) | リチウム二次電池用正極活物質とその製造方法、リチウム二次電池用正極、及びリチウム二次電池 | |
JP5544934B2 (ja) | リチウムイオン電池用正極活物質の製造方法 | |
US20100233540A1 (en) | Lithium iron phosphate having olivine structure and method for preparing the same | |
JP5928302B2 (ja) | リチウム二次電池用正極活物質の製造方法 | |
TWI619675B (zh) | 經碳塗覆的磷酸鋰鐵奈米粉末之製法 | |
JP5381192B2 (ja) | リチウムイオン二次電池用活物質の製造方法 | |
JP5915732B2 (ja) | 非水二次電池用正極活物質の製造方法、非水二次電池用正極の製造方法及び非水二次電池の製造方法 | |
JP5820521B1 (ja) | リチウム二次電池用正極材料及びその製造方法 | |
JP2014032803A (ja) | リチウム二次電池用正極活物質、及びリチウム二次電池 | |
JP5347605B2 (ja) | 活物質、これを含む電極、当該電極を含むリチウムイオン二次電池、及び活物質の製造方法 | |
US20210111404A1 (en) | Cathode active material for lithium ion secondary battery and method for producing same | |
JP6070222B2 (ja) | 非水系二次電池用正極活物質及びその製造方法、並びにその正極活物質を用いた非水系二次電池用正極を有する非水系二次電池 | |
JP2021150081A (ja) | リチウムイオン二次電池用正極材料、リチウムイオン二次電池用正極及びリチウムイオン二次電池 | |
JP2015056223A (ja) | 非水系二次電池用正極活物質、非水系二次電池用正極活物質の製造方法、非水系二次電池用正極および非水系二次電池 | |
JP2015002091A (ja) | リチウムイオン二次電池用正極活物質、それを用いたリチウムイオン二次電池用正極、リチウムイオン二次電池、リチウムイオン二次電池モジュール、及びリチウムイオン二次電池用正極活物質の製造方法 | |
US20220399545A1 (en) | Negative electrode active material and fabrication method thereof | |
KR101957233B1 (ko) | 리튬이차전지용 양극활물질 및 그 제조방법 | |
JP2015002092A (ja) | リチウムイオン二次電池用正極活物質及びリチウムイオン二次電池用正極活物質の製造方法 | |
KR102273771B1 (ko) | 리튬이차전지용 양극 활물질 및 그것을 포함하는 리튬이차전지 | |
US9825295B2 (en) | Positive electrode active material and lithium-ion secondary battery | |
KR101764474B1 (ko) | 리튬 망간인산화물 합성 방법 및 이로부터 제조된 다공성 리튬 망간인산화물 | |
JP2018156930A (ja) | 正極活物質、それを用いた正極及びリチウムイオン二次電池 | |
JP2018156823A (ja) | 正極活物質、それを用いた正極及びリチウムイオン二次電池 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 13823550 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2014527021 Country of ref document: JP Kind code of ref document: A |
|
ENP | Entry into the national phase |
Ref document number: 20157001740 Country of ref document: KR Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 14416394 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 13823550 Country of ref document: EP Kind code of ref document: A1 |