WO2015118849A1 - リチウムイオン二次電池用負極、リチウムイオン二次電池、リチウムイオン二次電池用負極用合材ペーストおよびリチウムイオン二次電池用負極の製造方法 - Google Patents
リチウムイオン二次電池用負極、リチウムイオン二次電池、リチウムイオン二次電池用負極用合材ペーストおよびリチウムイオン二次電池用負極の製造方法 Download PDFInfo
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- ion secondary
- lithium ion
- secondary battery
- carbon
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/134—Electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
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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
- H01M4/04—Processes of manufacture in general
- H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
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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
- H01M4/362—Composites
- H01M4/366—Composites as layered products
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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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/386—Silicon or alloys based on silicon
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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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/387—Tin or alloys based on tin
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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
- 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
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
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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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- 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
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
Definitions
- the present invention relates to a negative electrode for a lithium ion secondary battery, a lithium ion secondary battery, a composite paste for a negative electrode for a lithium ion secondary battery, and a method for producing a negative electrode for a lithium ion secondary battery.
- Non-aqueous secondary batteries such as lithium ion secondary batteries are widely used as power sources for various portable devices because of their high energy density, high voltage, and high capacity. Furthermore, in recent years, it has begun to be used for power tools such as electric tools, medium-sized and large-sized devices such as electric vehicles and electric bicycles.
- Silicon oxide (SiO x ) is attracting attention as such a material, but since this compound has a large volume expansion / contraction associated with the charge / discharge reaction, particles are pulverized little by little during each charge / discharge cycle of the battery. It has also been known that Si deposited on the surface reacts with the non-aqueous electrolyte to increase the irreversible capacity, and the battery swells due to charge / discharge. As a result, there is a case in which a so-called cycle characteristic lowering phenomenon that the capacity decreases due to repeated charging and discharging is exhibited. Various studies have been made to suppress this deterioration in cycle characteristics.
- Patent Document 3 For example, a method using a composite material of SiO x and a carbon material as a negative electrode active material (Patent Document 3), a method using graphite particles satisfying specific requirements as a carbon material (Patent Document 4), and the like have been proposed.
- Battery capacity Ah
- discharge capacity characteristics cycle characteristics
- the electrode active material is required to be a material having high conductivity.
- the present invention has been made in view of the above technical background, and has an object to provide a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery having high capacity and excellent cycle characteristics and load characteristics. To do.
- the gist of the present invention is as follows.
- a negative electrode for a lithium ion secondary battery including a laminate of an active material layer and a current collector The total pore volume and average pore diameter measured by the nitrogen gas adsorption method of the carbon particles (B) are 1.0 ⁇ 10 ⁇ 2 to 1.0 ⁇ 10 ⁇ 1 cm 3 / g, and 20
- a negative electrode for a lithium ion secondary battery characterized by having a thickness of ⁇ 50 nm.
- the ratio of the carbon coating (C) is 3 to 20% by mass.
- the average particle diameter D 50 (B) of the carbon particles (B) is 2.0 to 8.0 times the average particle diameter D 50 (A) of the alloy-based material (A) [1]
- the content of the alloy-based material (A) in the negative electrode active material layer is 10 to 60% by mass when the total of the alloy-based material (A) and the carbon particles (B) is 100% by mass. % Of the negative electrode for a lithium ion secondary battery according to any one of [1] to [4].
- the binder (D) is polyimide or polyamideimide.
- the carbon fiber has a fiber diameter of 2 to 1000 nm.
- a lithium ion secondary battery comprising the negative electrode for a lithium ion secondary battery according to any one of [1] to [11].
- the total pore volume and average pore diameter measured by the nitrogen gas adsorption method of the carbon particles (B) are 1.0 ⁇ 10 ⁇ 2 to 1.0 ⁇ 10 ⁇ 1 cm 3 / g, and 20
- a negative electrode mixture paste for lithium ion secondary batteries characterized by satisfying a range of ⁇ 50 nm.
- the binder material (D ′) is at least one selected from the group consisting of polyimide, a polyimide precursor, and polyamideimide, and the solvent (E) is N-methyl-2-pyrrolidone or N
- a method for producing a negative electrode for a lithium ion secondary battery comprising a step of applying and drying a negative electrode mixture paste for a lithium ion secondary battery on a current collector,
- the negative electrode mixture paste for a lithium ion secondary battery includes an alloy material (A) containing silicon or tin as a constituent element, a carbon coating (C) covering the surface of the alloy material (A), carbon particles ( B), containing the binder material (D ′) and the solvent (E), the total pore volume and the average pore diameter of the carbon particles (B) measured by the nitrogen gas adsorption method are each 1.0.
- the lithium ion secondary battery using the negative electrode of the lithium ion secondary battery of the present invention has a high capacity and exhibits good cycle characteristics and load characteristics.
- the negative electrode for a lithium ion secondary battery of the present invention comprises an alloy-based material (A) containing silicon or tin as a constituent element, a carbon coating (C) covering the surface of the alloy-based material (A), carbon particles (B), and A negative electrode for a lithium ion secondary battery comprising a laminate of a negative electrode active material layer containing a binder (D) and a current collector.
- This negative electrode active material layer comprises an alloy material (A) containing silicon or tin as a constituent element, a carbon coating (C) covering the surface of the alloy material (A), carbon particles (B), a binder material ( It is obtained by applying and drying a negative electrode mixture paste containing D ′) and a solvent (E) on a current collector.
- a negative electrode for a lithium ion secondary battery of the present invention will be described in the order of a negative electrode mixture paste and a negative electrode (negative electrode sheet), and finally a lithium ion secondary battery using the negative electrode will be described.
- high capacity means the time taken to discharge to 2.3 V at a discharge rate of 0.05 C after charging to 4.2 V at a charge rate of 0.05 C, and the negative electrode active material It means that the initial discharge capacity (unit: mAh / g) calculated from the mass is larger than 340 mAh / g which is the average of the initial discharge capacity of the existing carbon-based negative electrode.
- the charge rate and discharge rate (C rate) are values obtained by dividing the current value (A) by the capacity (Ah).
- the charge rate and the discharge rate are also referred to as a charge / discharge rate.
- a charge / discharge rate when a battery having a capacity of 1 Ah is charged or discharged at 0.05 A is expressed as 0.05 C.
- the negative electrode mixture paste according to the present invention includes an alloy material (A) containing silicon or tin as a constituent element, a carbon coating (C) that covers the surface of the alloy material (A), carbon particles (B), It comprises a binder material (D ′) and a solvent (E).
- A alloy material
- C carbon coating
- B carbon particles
- E solvent
- Alloy-based material containing silicon or tin as a constituent element (A) (Material containing silicon as a constituent element)
- alloy materials containing silicon as a negative electrode active material of the present invention include (i) silicon fine particles, (ii) tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium , Germanium, bismuth, antimony or chromium and an alloy of silicon, (iii) a compound of boron, nitrogen, oxygen or carbon and silicon, and (iv) a compound of boron, nitrogen, oxygen or carbon and silicon (ii) And those having a metal exemplified in (1).
- alloys or compounds containing silicon as a constituent element include SiB 4 , SiB 6 , Mg 2 Si, Ni 2 Si, TiSi 2 , MoSi 2 , CoSi 2 , NiSi 2 , CaSi 2 , CrSi 2 , Cu 5 Si, FeSi 2, MnSi 2, NbSi 2 , TaSi 2, VSi 2, WSi 2, ZnSi 2, SiC, Si 3 N 4, Si 2 N 2 O, SiO x (0.2 ⁇ x ⁇ 1.5) and LiSiO etc. Is included.
- alloy materials containing tin as a constituent element as a negative electrode active material of the present invention include (i) silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony Or an alloy of chromium and tin, (ii) a compound of oxygen or carbon and tin, and (iii) a compound of oxygen or carbon and tin and the metal exemplified in (i).
- the alloy or compound containing tin as a constituent element include SnO w (0 ⁇ w ⁇ 2), SnSiO 3 , LiSnO, Mg 2 Sn, and the like.
- the alloy-based material containing at least one of silicon and tin as a constituent element may be a simple substance, an alloy or a compound of silicon or tin, or two or more of them, or one or more phases thereof. May be at least partially included.
- the simple substance is a simple substance in a general sense (may contain a small amount of impurities), and does not necessarily mean 100% purity.
- the surface of these active materials may be coat
- the alloy material (A) containing silicon or tin as a constituent element is preferably a silicon oxide represented by SiO x (0.5 ⁇ x ⁇ 1.5).
- SiO x (0.5 ⁇ x ⁇ 1.5) is a general term for amorphous silicon oxides usually obtained from silicon dioxide (SiO 2 ) and metal silicon (Si) as raw materials. It is the general formula to represent.
- SiO x (0.5 ⁇ x ⁇ 1.5) if x is less than 0.5, the proportion of the Si phase increases, so that the volume change during charging / discharging becomes too large, and the lithium ion secondary The cycle characteristics of the battery deteriorate.
- x exceeds 1.5 the ratio of the Si phase decreases and the energy density decreases.
- a more preferable range of x is 0.7 ⁇ x ⁇ 1.2.
- the compounding amount of the alloy-based material (A) in the negative electrode mixture paste according to the present invention is 100% by mass when the total of the alloy-based material (A) as the negative electrode active material and the carbon particles (B) described later is 100% by mass.
- the blending ratio of the alloy material (A) is 10% by mass to 60% by mass, preferably 25% by mass to 50% by mass, and more preferably 31% by mass to 50% by mass.
- the lithium ion secondary battery using the negative electrode active material of this blending ratio has a negative electrode capacity deterioration due to the volume change of the active material. Since it can suppress, the cycle life of a lithium ion secondary battery can be extended.
- Carbon coating (C) covering the surface of the alloy-based material (A) is characterized by including a carbon coating (C) that covers the surface of an alloy-based material (A) containing silicon or tin as a constituent element.
- a carbon coating (C) that covers the surface of an alloy-based material (A) containing silicon or tin as a constituent element.
- the conductive network in the negative mix layer containing a negative electrode active material can be formed favorably, and the load characteristic of a battery can be improved.
- Examples of the method for coating the surface of the alloy material (A) with the carbon coating (C) include a method of performing thermal CVD treatment at a temperature of 800 ° C. or higher and 1300 ° C. or lower in an atmosphere of organic gas and / or steam.
- the amount of the carbon coating (C) is usually 3 to 20% by mass, preferably 3 to 15% by mass, more preferably 4 to 10% by mass with respect to the alloy-based material (A).
- a carbon coating (C) can be formed on the substrate.
- the carbon coating amount By setting the carbon coating amount to 20% by mass or less, the alloy-based material (A) in the negative electrode mixture paste becomes relatively high, so that a high capacity can be maintained.
- the carbon coating amount By setting the carbon coating amount to 3% by mass or more, the electron conductivity of the alloy-based material (A) can be made sufficient, and the battery capacity can be made sufficient.
- the time of this thermal CVD process is suitably set in relation to the amount of coating carbon. In the case where silicon oxide is contained in the alloy material (A) which is a coating target substance, the silicon oxide is changed (disproportionated) to a silicon-silicon oxide composite by the action of heat by this treatment.
- the carbon coating treatment is performed by heating at a temperature of preferably 700 ° C. or higher, more preferably 800 ° C. or higher, particularly preferably 900 ° C. to 1200 ° C.
- the higher the treatment temperature the fewer impurities remain, and the carbon coating (C) containing carbon having high conductivity can be formed.
- hydrocarbon-based gas a gas that can be thermally decomposed at the above heat treatment temperature to generate carbon (graphite) is selected particularly in a non-oxidizing atmosphere.
- hydrocarbon gases include hydrocarbons such as methane, ethane, ethylene, acetylene, propane, butane, butene, pentane, isobutane, hexane, cyclohexane, benzene, toluene, xylene, styrene, ethylbenzene, diphenylmethane, and naphthalene.
- aromatic hydrocarbons such as phenol, cresol, nitrobenzene, chlorobenzene, indene, coumarone, pyridine, anthracene and phenanthrene.
- Carbon particles (B) which are one of the constituent materials of the negative electrode material mixture paste according to the present invention contain a graphite material.
- the carbon particles (B) may be graphite particles themselves, particles composed of graphite particles and a carbonaceous layer existing on the surface thereof (that is, carbon-coated graphite particles), or carbon-coated graphite.
- the particles may be particles or particles obtained by attaching carbon fibers to graphite particles, but graphite particles are preferably used.
- the total pore volume and average pore diameter measured by the nitrogen gas adsorption method of the carbon particles (B) are usually 1.0 ⁇ 10 ⁇ 2 to 1.0 ⁇ 10 ⁇ 1 cm 3 / g and 20 respectively. It is characterized by simultaneously satisfying the range of ⁇ 50 nm, preferably satisfying the range of 1.5 ⁇ 10 ⁇ 2 to 9.0 ⁇ 10 ⁇ 2 cm 3 / g and 25 to 40 nm, more preferably 2.0 The ranges of ⁇ 10 ⁇ 2 to 7.0 ⁇ 10 ⁇ 2 cm 3 / g and 25 to 35 nm are simultaneously satisfied.
- the carbon particles (B) are preferably secondary aggregates formed by aggregating or bonding the primary particles containing the graphite material.
- the shape of the primary particles of the carbon particles (B) is preferably flat.
- carbon particles having such a shape are used, good conductivity is maintained even after the charge / discharge cycle, so that an increase in electrode resistance is suppressed and the cycle life of the lithium ion secondary battery can be extended.
- Examples of the carbon particles (B) made of flat primary particles include MAG (registered trademark).
- the average particle diameter D 50 (B) By setting the average particle diameter D 50 (B) to 2.0 or more of the average particle diameter D 50 (A) of the alloy-based material (A), the volume change of the active material accompanying the charge / discharge cycle is reduced, It is difficult for the capacity to decrease due to a part of the electrode having poor conduction.
- the average particle diameter D 50 (B) by making the average particle diameter D 50 (B) not more than 8.0 times the average particle diameter D 50 (A) of the alloy-based material (A), the specific surface area of the active material does not become too large, The capacity is less likely to decrease due to the decomposition reaction of the electrolytic solution.
- the negative electrode mixture paste according to the present invention may include a conductive material as a conductive auxiliary agent (C ′).
- a conductive material is not particularly limited as long as it does not cause a chemical change in the non-aqueous secondary battery.
- carbon black thermal black, furnace black, channel black, ketjen black, acetylene black
- carbon fiber carbon fiber
- metal powder copper, nickel, aluminum, silver, etc.
- metal fiber polyphenylene derivative, and the like, among which carbon fiber is preferred.
- the conductive additive (C ′) preferably comprises carbon fibers having an aspect ratio of 10 to 1000, preferably 10 to 500.
- the volume expansion of the alloy-based material (A) is absorbed by the elastic deformation of the carbon particles (B) inside to suppress the swelling of the electrode.
- the pores of the carbon particles (B) are reduced in volume due to elastic deformation, and therefore, it is expected that the electrolyte solution retention is reduced. If the electrolyte solution retention is reduced, the ionic conductivity is lowered, which not only causes a reduction in capacity and load characteristics, but also the utilization rate of the active material is not uniform, resulting in a local increase in utilization rate. The active material deteriorates.
- the contact between the conductive auxiliary agents (C ′) decreases due to repeated volume changes of the alloy-based material (A).
- the electrode resistance increases as the cycle increases.
- the amount of effective active material decreases due to conduction interruption.
- an increase in electrode resistance and a decrease in the amount of effective active material can be suppressed by using an active material that can suppress electrode swelling, such as the carbon particles (B) in the above form.
- the method for producing carbon fibers used as the conductive additive (C ′) in the present invention is not particularly limited. Examples thereof include a method in which a polymer is formed into a fiber by a spinning method and heat-treated in an inert atmosphere, and a vapor phase growth method in which an organic compound is reacted at a high temperature in the presence of a catalyst. Carbon fibers obtained by vapor phase growth, so-called vapor phase growth carbon fibers, have a crystal growth direction substantially parallel to the fiber axis, so that the crystallinity in the fiber length direction of the graphite structure tends to be high, and relatively short fibers. A carbon fiber having a diameter, high conductivity, and high strength is obtained.
- the content of the conductive additive (C ′) is usually 0.5 to 10% by mass, preferably based on the total mass of the alloy-based material (A) and the carbon particles (B) as the negative electrode active material. Is 1 to 8% by mass, more preferably 2 to 5% by mass. In the electrode, the range of 0.05 to 20% by mass is preferable with respect to the total mass of the electrode, preferably 0.1 to 15% by mass, and more preferably 0.5 to 10% by mass.
- the active material ratio in the electrode can be made sufficient, and the capacity of the lithium ion battery can be made sufficient.
- the said electrolyte solution permeable effect with respect to an electrode can fully be expressed by content being 0.5 mass% or more.
- the content of the conductive auxiliary agent (C ′) can be adjusted to the above range by adding each component so as to be the ratio at the time of preparing the composite paste.
- the above aspect ratio can be calculated by dividing the fiber length by the fiber diameter obtained by SEM image analysis, for example.
- the preferred fiber diameter range varies depending on the type of carbon fiber used and the fiber diameter, but it is 2 to 1000 nm, more preferably 2 to 500 nm.
- Examples of the conductive aid (C ′) having a preferable range of the fiber diameter include vapor grown carbon fiber (VGCF) and carbon nanotube (CNT). You may use the said conductive support agent (C ') individually or in combination of 2 or more types.
- a conductive auxiliary agent (C′) in the present invention a conductive auxiliary agent (C′-1) satisfying the above aspect ratio and a conductive auxiliary agent (C′-2) not satisfying the above aspect ratio may be used in combination.
- a typical example of the conductive auxiliary agent (C′-2) that does not satisfy the aspect ratio is a carbon material.
- the conductive auxiliary agent (C′-2) is preferably a conductive carbon material.
- the type of the conductive carbon material is not particularly limited, but may be graphite (graphite) such as artificial graphite or natural graphite, or an organic pyrolysis product under various pyrolysis conditions.
- Binder material (D ′) and solvent (E) The binder material (D ′) is used as a binder for fixing the negative electrode active material and the conductive additive (C ′) made of the alloy material (A) and the carbon particles (B) to the current collector.
- the used amount of the binder material (D ′) is 0.5 to 0.5 based on the total amount of the alloy-based material (A), the carbon particles (B), the conductive auxiliary agent (C ′) and the binder material (D ′). 50% by mass is preferable.
- the amount of the binder material (D ′) used is 0.5% by mass or more, so that the moldability of the electrode is further increased. Can be.
- the binder material (D ′) includes fluoropolymers such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubbers such as styrene butadiene rubber (SBR), polyimide, polyimide precursor, polyamide Examples thereof include imide-based polymers such as imides and alkoxysilyl group-containing resins. Of these, polyimides having excellent binding properties, polyimide precursors and polyamideimides are preferred.
- PVDF polyvinylidene fluoride
- PTFE polytetrafluoroethylene
- SBR styrene butadiene rubber
- imide-based polymers such as imides and alkoxysilyl group-containing resins.
- polyimides having excellent binding properties polyimide precursors and polyamideimides are preferred.
- the solvent (E) at the time of preparing the composite paste is not particularly limited as long as it can uniformly dissolve or disperse the binder material (D '), the active material, and other substances optionally contained.
- the solvent (E) is preferably an aprotic polar solvent, such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, and 1,3. Examples include -dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more.
- polyimide a polyimide precursor or polyamideimide is used as the binder material (D ')
- N-methyl-2-pyrrolidone or N, N-dimethylacetamide is used as the solvent (E).
- the amount of the solvent is appropriately set in consideration of the viscosity of the composite paste. It is preferable to blend 50 to 900 parts by mass, and more preferably 65 to 500 parts by mass with respect to 100 parts by mass of the solid content contained in the composite paste.
- a negative electrode paste for a lithium ion secondary battery includes a material for electrode binder (D ') for a lithium ion secondary battery or a varnish containing the material and a negative electrode active material component Alloy-based material (A), carbon particles (B), carbon coating (C), conductive additive (C ′), solvent (E), and various additions as necessary It can be manufactured by mixing and stirring or kneading agents. Examples of the mixing method of the raw materials include the following two methods, but are not limited thereto. i) A conductive additive (C ′) is added to a varnish containing an electrode binder material (D ′) for a lithium ion secondary battery and kneaded.
- An active material and a solvent are added to the obtained kneaded material to obtain a negative electrode mixture paste.
- a conductive additive (C ′) is added to a varnish containing an electrode binder material (D ′) for a lithium ion secondary battery, and an active material is further added and kneaded.
- a solvent is added to the kneaded material obtained and stirred to obtain a negative electrode mixture paste.
- the stirring may be normal stirring using a stirring blade or the like, or stirring using a rotation / revolution mixer or the like. For the kneading operation, a kneader or the like can be used.
- the negative electrode for a lithium ion secondary battery of the present invention is a laminate of a current collector and a negative electrode active material layer.
- the negative electrode for a lithium ion secondary battery may be a sheet electrode.
- Negative electrode active material layer is a cured product of the above-described negative electrode mixture paste for lithium ion secondary batteries. That is, it contains an alloy-based material (A) that is a negative electrode active material, carbon particles (B), and a binder (D) that binds the carbon particles (B), and further contains other components (such as a conductive auxiliary agent (C ′)). Optionally included.
- the binder (D) is obtained by curing the binder material (D ′) contained in the negative electrode mixture paste by drying.
- the binder (D) is preferably a polyimide or polyamideimide obtained by heating a binder material (D ′) selected from polyimide, a precursor of polyimide and polyamideimide.
- the thickness of the negative electrode active material layer is not particularly limited and is preferably, for example, 5 ⁇ m or more, more preferably 10 ⁇ m or more. Moreover, it is preferable to set it as 200 micrometers or less, More preferably, it is 100 micrometers or less, More preferably, it is 75 micrometers or less. If the negative electrode active material layer is too thin, the practicality as an electrode is lacking due to the balance with the particle size of the active material. On the other hand, if the thickness is too thick, it may be difficult to obtain a sufficient Li occlusion / release function for charge / discharge at a high charge / discharge rate.
- the applied negative electrode mixture paste can be dried, for example, by heat curing.
- Heat curing can usually be performed under atmospheric pressure, but may be performed under pressure or under vacuum.
- the atmosphere at the time of heating and drying is not particularly limited, but is usually preferably performed in an atmosphere of air, nitrogen, helium, neon, argon, or the like, and more preferably in an atmosphere of nitrogen or argon as an inert gas.
- the heating temperature in the heat curing of the negative electrode mixture paste is usually 150 ° C. to 500 ° C. for 1 minute to 24 hours.
- the temperature is preferably 200 ° C. to 350 ° C. for 1 minute to 20 hours in order to obtain a reliable negative electrode.
- the positive electrode current collector is a thin film
- its thickness is arbitrary, but it is usually 1 ⁇ m or more, preferably 3 ⁇ m or more, more preferably 5 ⁇ m or more. Moreover, it is 100 mm or less normally, Preferably it is 1 mm or less, More preferably, it is 50 micrometers or less. If the thickness is less than the above range, the strength required for the current collector may be insufficient. On the other hand, if it is thicker than the above range, the handleability may be impaired.
- the conductive material is not particularly limited as long as it can be mixed with an appropriate amount in the active material to impart conductivity, but is usually carbon powder such as acetylene black, carbon black, and graphite, various metal fibers, powder, and foil. Etc.
- the thickness of the positive electrode active material layer is usually about 10 to 200 ⁇ m.
- the density of the positive electrode active material layer (calculated from the mass and thickness of the positive electrode mixture layer per unit area laminated on the current collector) is preferably 3.0 to 4.5 g / cm 3.
- a separator is usually disposed between the separator positive electrode and the negative electrode. Thereby, a short circuit between the electrodes is prevented.
- the separator is usually a porous body such as a porous film or a nonwoven fabric.
- the porosity of the separator is appropriately set according to the permeability of electrons and ions, the material of the separator, and the like, but generally it is preferably 30 to 80%.
- the electrolytic solution contains a solvent and an electrolyte salt dissolved in the solvent.
- the solvent is, for example, one or more of nonaqueous solvents (organic solvents) described below.
- nonaqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, ⁇ -butyrolactone, ⁇ -valerolactone, 1,2-dimethoxyethane, and tetrahydrofuran.
- At least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate is preferable. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.
- a high viscosity (high dielectric constant) solvent such as ethylene carbonate or propylene carbonate (for example, a relative dielectric constant ⁇ ⁇ 30) and a low viscosity solvent such as dimethyl carbonate, ethyl methyl carbonate or diethyl carbonate (for example, viscosity ⁇ 1 mPa ⁇ s) is more preferable.
- the solvent may be a cyclic carbonate having one or more unsaturated carbon bonds (unsaturated carbon bond cyclic carbonate).
- unsaturated carbon-bonded cyclic ester carbonate examples include vinylene carbonate and vinyl ethylene carbonate.
- content of unsaturated carbon bond cyclic carbonate in a nonaqueous solvent is 0.01 mass% or more and 10 mass% or less, for example. This is because the decomposition reaction of the electrolytic solution is suppressed without excessively reducing the battery capacity.
- the solvent may be sultone (cyclic sulfonate ester). This is because the chemical stability of the electrolytic solution is improved.
- the sultone is, for example, propane sultone or propene sultone.
- content of sultone in a nonaqueous solvent is 0.5 mass% or more and 5 mass% or less, for example. This is because the decomposition reaction of the electrolytic solution is suppressed without excessively reducing the battery capacity.
- the solvent may be an acid anhydride.
- the acid anhydride include dicarboxylic acid anhydride, disulfonic acid anhydride, and carboxylic acid sulfonic acid anhydride.
- the dicarboxylic acid anhydride include succinic anhydride, glutaric anhydride, and maleic anhydride.
- the disulfonic anhydride include ethanedisulfonic anhydride and propanedisulfonic anhydride.
- the electrolyte salt is, for example, any one or more of lithium salts described below.
- the electrolyte salt may be a salt other than the lithium salt (for example, a light metal salt other than the lithium salt).
- lithium salt examples include the following compounds. Lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), or lithium hexafluoroarsenate (LiAsF 6 ). Lithium tetraphenylborate (LiB (C 6 H 5) 4), lithium methanesulfonate (LiCH 3 SO 3), is lithium trifluoromethane sulfonate (LiCF 3 SO 3) or lithium tetrachloroaluminate (LiAlCl 4) . It is dilithium hexafluorosilicate (Li 2 SiF 6 ), lithium chloride (LiCl) or lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.
- LiPF 6 Lithium hexafluorophosphate
- LiBF 4 lithium perchlor
- the form of the lithium ion secondary battery of the present invention is not particularly limited.
- Examples of the form of the lithium ion secondary battery include a cylinder type in which the sheet electrode and the separator are spiral, a cylinder type having an inside-out structure in which the pellet electrode and the separator are combined, a coin type in which the pellet electrode and the separator are stacked, and the like. It is done. Moreover, it is good also as arbitrary shapes, such as a coin type
- the procedure for assembling the lithium ion secondary battery is not particularly limited, and may be assembled by an appropriate procedure according to the structure of the battery.
- a negative electrode is placed on an outer case, an electrolyte and a separator are provided on the outer case, and a positive electrode is placed so as to face the negative electrode.
- the battery is then caulked together with a gasket and a sealing plate.
- the average particle size (D 50 ) was calculated by measuring the particle size distribution by a laser diffraction method and calculating the particle size corresponding to an integrated value of the volume distribution of 50%.
- the average fiber diameter was determined by SEM image analysis.
- the aspect ratio was calculated from the fiber length by the fiber diameter determined by SEM image analysis.
- Electrode binder resin composition [Example 1] ⁇ Preparation of electrode binder resin composition> A container equipped with a stirrer and a nitrogen introduction tube was charged with 32.44 g (0.3 mol) of p-PD, 36.84 g of m-BP (0.1 mol), and 532.7 g of NMP as a solvent. The solution was heated to 50 ° C. and stirred until p-PD and m-BP were dissolved. After the temperature of the solution was lowered to room temperature, 115.33 g (0.392 mol) of BPDA was added over about 30 minutes, 228.3 g of NMP was further added, and the mixture was stirred for 20 hours, followed by electrode binder resin composition A Got. The obtained electrode binder resin composition had a solid content concentration of 18% by mass and a logarithmic viscosity of 0.89 dl / g.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- the battery was charged to 0.05V at 0.05C. Thereafter, the battery was discharged to 0.05 V at 0.05 C, and the load characteristics were calculated by the following formula 2.
- Example 2 An electrode binder resin composition A containing 10 parts by weight of polyimide and 3 parts by weight of a conductive additive (made by Showa Denko, VGCF-H) were mixed with a battery compound stirrer (Primics Co., Ltd., TK Hibismix Model 2P). -03). The total amount of silicon oxide coated with a carbon coating (manufactured by Shin-Etsu Chemical Co., KSC-1064, average particle size 5 ⁇ m) and carbon particles (manufactured by Hitachi Chemical Co., Ltd., SMG-N-HP1-10) was added to the obtained paste. 87 parts by mass was added and further kneaded to prepare a negative electrode mixture paste. The mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- Example 3 The cell produced in Example 1 was allowed to stand at 25 ° C. for 12 hours, and then the battery was evaluated in the same manner as in Example 1. The results are shown in Table 1.
- Example 4 An electrode binder resin composition A containing 10 parts by weight of polyimide and 3 parts by weight of a conductive additive (manufactured by Denki Kagaku, Denka Black) were added to a battery compound stirrer (Primix Co., Ltd., TK Hibismix Model 2P- 03). A total of 87 parts by mass of silicon oxide coated with a carbon coating (manufactured by Shin-Etsu Chemical Co., Ltd., KSC-1064, average particle size 5 ⁇ m) and carbon particles (manufactured by Hitachi Chemical Co., Ltd., MAGD-20) are added to the obtained paste. Further, kneading was performed to prepare an electrode paste. The mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- a conductive additive manufactured by Denki Kagaku, Denka Black
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode. Using the obtained negative electrode, a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- Example 5 An electrode binder resin composition A containing 10 parts by weight of polyimide and 3 parts by weight of a conductive additive (manufactured by Lion, Ketjen Black) were mixed with a battery compound stirrer (Primix Co., Ltd., TK Hibismix Model 2P- 03). A total of 87 parts by mass of silicon oxide coated with a carbon coating (manufactured by Shin-Etsu Chemical Co., Ltd., KSC-1064, average particle size 5 ⁇ m) and carbon particles (manufactured by Hitachi Chemical Co., Ltd., MAGD-20) are added to the obtained paste. Further, kneading was performed to prepare an electrode paste. The mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode. Using the obtained negative electrode, a coin cell was prepared in the same manner as in the example, and the battery was evaluated. The results are shown in Table 1.
- Example 6 Silicon oxide (manufactured by Shin-Etsu Chemical Co., Ltd., KSC-1064, average particle size 5 ⁇ m), carbon particles (manufactured by Hitachi Chemical Co., Ltd., MAGD) coated with a carbon coating on electrode binder resin composition A containing 10 parts by mass of polyimide A total of 87 parts by mass of -20) was added and kneaded to prepare an electrode paste.
- the mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- Example 8 An electrode binder resin composition A containing 10 parts by weight of polyimide and 3 parts by weight of a conductive additive (manufactured by Electrochemical Co., Ltd., Denka Black) were mixed with a battery compound stirrer (Primix Co., Ltd., TK Hibismix Model 2P- 03). The total amount of silicon oxide coated with a carbon coating (manufactured by Shin-Etsu Chemical Co., KSC-1064, average particle size 5 ⁇ m) and carbon particles (manufactured by Hitachi Chemical Co., Ltd., SMG-N-HP1-10) was added to the obtained paste. 87 parts by mass was added and further kneaded to prepare a negative electrode mixture paste. The mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- a conductive additive manufactured by Electrochemical Co., Ltd., Denka Black
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- the mass ratio between the silicon oxide as the active material and the carbon particles was 30:70.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in the example, and the battery was evaluated. The results are shown in Table 1.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- This electrode paste is applied to a copper foil as a current collector (rolled copper foil manufactured by Nihon Foil Co., Ltd., thickness: 18 ⁇ m) using an applicator, and cured by heat treatment at 350 ° C. for 10 minutes in a nitrogen atmosphere. To produce a negative electrode.
- the negative electrode composite material mass after drying was 4.4 mg / cm 2 per unit area.
- a coin cell was prepared in the same manner as in Example 1, and the battery was evaluated. The results are shown in Table 1.
- Examples 1 to 8 were all high-capacity lithium ion secondary batteries.
- An alloy-based material (A) coated with a carbon coating (C), a total pore volume and an average pore diameter of 1.0 ⁇ 10 ⁇ 2 to 1.0 ⁇ 10 ⁇ 1 cm 3 / g, and Examples 1 to 8 using carbon particles (B) of 20 to 50 nm were compared with Comparative Examples 1 and 2 not using the carbon particles (B) described above, and the discharge capacity retention rate and load characteristics at 100 cycles. It turned out to be excellent.
- Examples 1 and 2 were superior in load characteristics as compared with Comparative Example 3 in which the alloy-based material (A) not coated with the carbon film (C) was used.
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Abstract
Description
[1]ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)およびバインダー(D)を含有する負極活物質層と、集電体と、の積層体を含むリチウムイオン二次電池用負極であって、
該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmであることを特徴とするリチウムイオン二次電池用負極。
[2]前記負極活物質層における、前記合金系材料(A)と前記炭素被膜(C)の合計を100質量%としたときの、前記炭素被膜(C)の割合が、3~20質量%である[1]に記載のリチウムイオン二次電池用負極。
[3]前記合金系材料(A)がSiOx(0.5≦x≦1.5)で表されるケイ素酸化物である[1]または[2]に記載のリチウムイオン二次電池用負極。
[4]前記炭素粒子(B)の平均粒子径D50(B)が、前記合金系材料(A)の平均粒子径D50(A)の2.0~8.0倍である[1]~[3]のいずれかに記載のリチウムイオン二次電池用負極。
[5]前記負極活物質層における、前記合金系材料(A)と前記炭素粒子(B)の合計を100質量%としたときの、合金系材料(A)の含有率が、10~60質量%である[1]~[4]のいずれかに記載のリチウムイオン二次電池用負極。
[6]前記炭素粒子(B)が、扁平状の黒鉛材料が集合または結合してなる[1]~[5]のいずれかに記載のリチウムイオン二次電池用負極。
[7]前記バインダー(D)が、ポリイミドまたはポリアミドイミドである[1]~[6]のいずれかに記載のリチウムイオン二次電池用負極。
[8]さらに、導電助剤(C’)を含む[1]~[7]のいずれかに記載のリチウムイオン二次電池用負極。
[9]前記導電助剤(C’)が、アスペクト比が10~1000である炭素繊維を含む[8]に記載のリチウムイオン二次電池用負極。
[10]前記炭素繊維の繊維径が2~1000nmである[9]に記載のリチウムイオン二次電池用負極。
[11]前記炭素繊維が、気相法炭素繊維である[9]または[10]に記載のリチウムイオン二次電池用負極。
[12][1]~[11]のいずれか1項に記載のリチウムイオン二次電池用負極を含むリチウムイオン二次電池。
[13]ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)、バインダー用材料(D’)および溶媒(E)を含有するリチウムイオン二次電池用負極用合材ペーストであって、
該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmの範囲を満たすことを特徴とするリチウムイオン二次電池用負極用合材ペースト。
[14]前記バインダー用材料(D’)が、ポリイミド、ポリイミドの前駆体およびポリアミドイミドからなる群から選ばれる少なくとも1つであり、前記溶媒(E)が、N-メチル―2-ピロリドンまたはN,N-ジメチルアセトアミドである[13]に記載のリチウムイオン二次電池用負極用合材ペースト。
[15]リチウムイオン二次電池用負極用合材ペーストを集電体上に塗布・乾燥する工程を含むリチウムイオン二次電池用負極の製造方法であって、
前記リチウムイオン二次電池用負極用合材ペーストは、ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)、バインダー用材料(D’)および溶媒(E)を含有し、該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmの範囲を満たすことを特徴とする、方法。
本発明に関わる負極用合材ペーストは、ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)、バインダー用材料(D’)および溶媒(E)を含んでなる。以下、各成分について詳説する。
(ケイ素を構成元素として含む材料)
本発明の負極活物質としてのケイ素を構成元素として含む合金系材料の例には、(i)シリコン微粒子、(ii)スズ、ニッケル、銅、鉄、コバルト、マンガン、亜鉛、インジウム、銀、チタン、ゲルマニウム、ビスマス、アンチモンまたはクロムと、ケイ素との合金、(iii)ホウ素、窒素、酸素または炭素とケイ素との化合物、および(iv)ホウ素、窒素、酸素または炭素とケイ素との化合物と(ii)に例示した金属とを有するものなどが含まれる。ケイ素を構成元素として含む合金または化合物の例には、SiB4、SiB6、Mg2Si、Ni2Si、TiSi2、MoSi2、CoSi2、NiSi2、CaSi2、CrSi2、Cu5Si、FeSi2、MnSi2、NbSi2、TaSi2、VSi2、WSi2、ZnSi2、SiC、Si3N4、Si2N2O、SiOx(0.2≦x≦1.5)およびLiSiOなどが含まれる。
本発明の負極活物質としてのスズを構成元素として含む合金系材料の例には、(i)ケイ素、ニッケル、銅、鉄、コバルト、マンガン、亜鉛、インジウム、銀、チタン、ゲルマニウム、ビスマス、アンチモンまたはクロムと、スズとの合金、(ii)酸素または炭素とスズとの化合物、および(iii)酸素または炭素とスズとの化合物と(i)に例示した金属とを有するものなどが挙げられる。スズを構成元素として含む合金または化合物の例には、SnOw(0<w≦2)、SnSiO3、LiSnOおよびMg2Snなどが含まれる。
本発明に関わる負極用合材ペーストは、ケイ素またはスズを構成元素として含む合金系材料(A)の表面を被覆する炭素被膜(C)を含むことを特徴としている。このように炭素被膜(C)で被覆することによって、負極活物質を含む負極合材層中の導電ネットワークを良好に形成し、電池の負荷特性を向上することができる。合金系材料(A)の表面に炭素被膜(C)を被覆する方法としては、有機物ガス及び/又は蒸気の雰囲気下、温度800℃以上1300℃以下での熱CVD処理する方法が挙げられる。熱CVD法による場合、炭素被膜(C)の量が、合金系材料(A)に対して通常3~20質量%、好ましくは3~15質量%、より好ましくは4~10質量%となるように炭素被膜(C)を形成することができる。炭素被膜量を20質量%以下とすることで、負極用合材ペースト中の合金系材料(A)が相対的に高くなるため、高容量を維持することができる。炭素被膜量を3質量%以上とすることで、合金系材料(A)の電子伝導性を十分にして、電池容量を十分にすることができる。なお、この熱CVD処理の時間は、被覆炭素量との関係で適宜設定される。被覆対象物質である合金系材料(A)の中に酸化珪素が含まれる場合は、この処理による熱の作用で酸化珪素がケイ素-ケイ素酸化物系複合体に変化(不均化)する。
本発明に係る負極材合材ペーストの構成物質の一つである炭素粒子(B)は、黒鉛材料を含有するものである。炭素粒子(B)は、黒鉛粒子そのものであってもよいし、黒鉛粒子とその表面に存在する炭素質層とからなる粒子(すなわち、炭素被覆黒鉛粒子)であってもよいし、炭素被覆黒鉛粒子または黒鉛粒子に炭素繊維を付着させてなる粒子であってもよいが、好ましくは黒鉛粒子が用いられる。
本発明に関わる負極用合材ペーストは、導電助剤(C’)としての導電性材料を含んでもよい。このような導電性材料としては、非水二次電池内において化学変化を起こさないものであれば特に限定されず、例えば、カーボンブラック(サーマルブラック、ファーネスブラック、チャンネルブラック、ケッチェンブラック、アセチレンブラック等)、炭素繊維、金属粉(銅、ニッケル、アルミニウム、銀等の粉末)、金属繊維、ポリフェニレン誘導体等の材料を用いることができ、これらの中では炭素繊維が好ましい。
バインダー用材料(D’)は、合金系材料(A)および炭素粒子(B)からなる負極活物質及び導電助剤(C’)を集電体に固定するための結着剤として用いられる。バインダー用材料(D’)の使用量は、合金系材料(A)、炭素粒子(B)、導電助剤(C’)およびバインダー用材料(D’)の合計量に対して0.5~50質量%が好ましい、バインダー用材料(D’)の使用量を0.5質量%以上とすることで電極の成形性をより高くし、50質量%以下とすることで電極のエネルギー密度を十分にすることができる。なお、バインダー用材料(D’)としては、ポリフッ化ビニリデン(PVDF)、ポリテトラフルオロエチレン(PTFE)等のフッ素系ポリマー、スチレンブタジエンゴム(SBR)等のゴム、ポリイミド、ポリイミドの前駆体、ポリアミドイミド等のイミド系ポリマー、アルコキシシリル基含有樹脂などを例示することができる。また、これらの中でも結着性に優れたポリイミド、ポリイミドの前駆体およびポリアミドイミドが好ましい。
リチウムイオン二次電池用負極用合材ペーストは、リチウムイオン二次電池用電極バインダー用材料(D’)もしくはこれを含むワニスと、負極活物質構成成分である合金系材料(A)と、炭素粒子(B)と、必要に応じて炭素被膜(C)、導電助剤(C’)、溶剤(E)、および必要に応じて添加される各種添加剤等を混合し、撹拌ないし混錬して製造し得る。各原料の混合方法としては、以下の2つの方法が挙げられるが、これに限定されない。
i)リチウムイオン二次電池用電極バインダー用材料(D’)を含むワニスに、導電助剤(C’)を添加して混練する。得られた混練物に、活物質および溶媒を加えて負極用合材ペーストとする。
ii)リチウムイオン二次電池用電極バインダー用材料(D’)を含むワニスに、導電助剤(C’)を添加し、さらに、活物質を添加して混練する。得られた混練物に溶媒を加えて撹拌して負極用合材ペーストとする。
上記攪拌は、攪拌羽根等を用いた通常撹拌や、自転・公転ミキサー等を用いた撹拌であればよい。混練操作は、混練機などを用いることができる。
本発明のリチウムイオン二次電池用負極は、集電体と負極活物質層との積層体である。リチウムイオン二次電池用負極は、シート状電極であってもよい。
負極活物質層は、前述のリチウムイオン二次電池用負極用合材ペーストの硬化物である。つまり、負極活物質である合金系材料(A)と、炭素粒子(B)と、それを結着するバインダー(D)とを含み、さらにその他の成分(導電助剤(C’)など)を任意に含む。なお、バインダー(D)は、負極用合材ペーストに含まれるバインダー用材料(D’)を乾燥により硬化させてなる。バインダー(D)は、好ましくは、ポリイミド、ポリイミドの前駆体およびポリアミドイミドから選択されるバインダー用材料(D’)の加熱によって得られるポリイミドまたはポリアミドイミドである。なお、負極活物質層における合金系材料(A)、炭素被膜(C)、炭素粒子(B)およびその他の成分(導電助剤(C’)など)の量比は、上記負極用合材ペーストにおける各成分の量比とほぼ同一となる。
負極の集電体の材質は、ケイ素及び/又はケイ素合金、スズおよびその合金、ケイ素-銅合金、銅、ニッケル、ステンレス鋼、ニッケルメッキ鋼等の金属材料や、カーボンクロス、カーボンペーパー等の炭素材料などでありうる。
負極の集電体の形状は、金属材料の場合、金属箔、金属円柱、金属コイル、金属板、金属薄膜等が、炭素材料の場合、炭素板、炭素薄膜、炭素円柱等でありうる。集電体の厚みは、特に制限はないが、例えば通常5μm~30μmであり、好ましくは6~20μmである。さらに、集電体表面は、化学処理もしくは物理処理によって、表面を粗化してあってもよいし、表面にカーボンブラック、アセチレンブラックなどの導電材を塗布したものであってもよい。
負極(シート)は、前述の負極用合材ペーストを集電体に塗布し、それを乾燥させて負極活物質層とすることで得られる。塗布した負極用合材ペーストを乾燥させると、溶媒(E)が除去され、バインダー用材料(D’)が集電体と接着しつつ硬化して、負極活物質層と集電体との積層体を形成することができる。負極用合材ペーストの塗布は、例えばスクリーン印刷、ロールコート、スリットコート等の方法で行い得る。負極用合材ペーストをパターン状に塗布することで、メッシュ状の活物質層が形成されうる。
本発明のリチウムイオン二次電池の基本構成は、従来公知のリチウムイオン二次電池と同様である。通常のリチウムイオン二次電池は、リチウムイオンを吸蔵・放出可能な一対の電極(負極と正極)、セパレータ、および電解質を備える。
本発明のリチウムイオン二次電池における負極は、前述の負極である。
[2] 正極
正極は、集電体と、正極活物質層とが積層された積層体とし得る。正極の集電体の材質としては、通常、アルミニウム、ステンレス鋼、ニッケルメッキ、チタン、タンタル等の金属材料や、カーボンクロス、カーボンペーパー等の炭素材料が用いられる。中でも金属材料が好ましく、アルミニウムが特に好ましい。集電体の形状としては、金属材料の場合、金属箔、金属円柱、金属コイル、金属板、金属薄膜、エキスパンドメタル、パンチメタル、発泡メタル等が、炭素材料の場合、炭素板、炭素薄膜、炭素円柱等が挙げられる。中でも、金属薄膜が、現在工業化製品に使用されているため好ましい。なお、薄膜は適宜メッシュ状に形成しても良い。
正極と負極との間に、通常、セパレータを配置する。それにより、電極間の短絡を防止する。セパレータは、通常、多孔膜や不織布などの多孔性体である。セパレータの空孔率は、電子やイオンの透過性、セパレータの素材などに応じて適宜設定されるが、一般的に30~80%であることが望ましい。
電解液は、溶媒と、それに溶解された電解質塩とを含んでいる。溶媒は、例えば、以下で説明する非水溶媒(有機溶媒)のいずれか1種類または2種類以上である。前記非水溶媒として、炭酸エチレン、炭酸プロピレン、炭酸ブチレン、炭酸ジメチル、炭酸ジエル、炭酸エチルメチル、炭酸メチルプロピル、γ-ブチロラクトン、γ-バレロラクトン、1,2-ジメトキシエタンまたはテトラヒドロフランが挙げられる。前記非水溶媒の他の例として、2-メチルテトラヒドロフラン、テトラヒドロピラン、1,3-ジオキソラン、4-メチル-1,3-ジオキソラン、1,3-ジオキサンまたは1,4-ジオキサンが挙げられる。前記非水溶媒の他の例として、酢酸メチル、酢酸エチル、プロピオン酸メチル、プロピオン酸エチル、酪酸メチル、イソ酪酸メチル、トリメチル酢酸メチルまたはトリメチル酢酸エチルが挙げられる。前記非水溶媒の他の例として、アセトニトリル、グルタロニトリル、アジポニトリル、メトキシアセトニトリル、3-メトキシプロピオニトリル、N,N-ジメチルホルムアミド、N-メチルピロリジノンまたはN-メチルオキサゾリジノンが挙げられる。前記非水溶媒の他の例として、N,N’-ジメチルイミダゾリジノン、ニトロメタン、ニトロエタン、スルホラン、燐酸トリメチルまたはジメチルスルホキシドが挙げられる。
電解質塩は、例えば、以下で説明するリチウム塩のいずれか1種類または2種類以上である。ただし、電解質塩は、リチウム塩以外の他の塩(例えばリチウム塩以外の軽金属塩)でもよい。
本発明のリチウムイオン二次電池の形態は特に制限されない。リチウムイオン二次電池の形態の例としては、シート電極及びセパレータをスパイラル状にしたシリンダータイプ、ペレット電極及びセパレータを組み合わせたインサイドアウト構造のシリンダータイプ、ペレット電極及びセパレータを積層したコインタイプ等が挙げられる。また、これらの形態の電池を任意の外装ケースに収めることにより、コイン型、円筒型、角型、パウチ型等の任意の形状としてもよい。
本発明のリチウムイオン二次電池は、電池作製後20時間以上、好ましくは24時間以上48時間以下でエージングした後、初回充電を開始するとよい。
エージングとは、組み立てた電池を所定温度、所定時間で放置することを意味する。
エージング時間は、20時間以上、好ましくは24時間以上48時間以下である。本時間でエージングを行うことで、電池のサイクル寿命が向上する。エージング時間が20時間未満または、48時間より長くなると、電池のサイクル寿命が向上しない。
NMP:N-メチル-2-ピロリドン
p-PD:p-フェニレンジアミン
m-BP:4,4’-ビス(3-アミノフェノキシ)ビフェニル
BPDA:3,3’,4,4’-ビフェニルテトラカルボン酸二無水物
また、本実施例においては以下の方法で各種の物性を測定した。
炭素粒子の全細孔容積と平均細孔直径の算出は、液体温度下(77K)での窒素ガス吸着法を用いて、吸着等温線を測定することにより行った。測定には、日本ベル株式会社製のBELSORP-maxを使用し、測定前の前処理には、日本ベル株式会社製のBELPREP-vacIIにて、真空加熱脱気を行った。
なお、全細孔容積は得られた吸着等温線の相対圧0.99での吸着量から算出した。また、平均細孔径は、全細孔容積と、同じく吸着等温線から求めたBET比表面積により算出した。
平均粒径(D50)の算出は、レーザー回析法により粒度分布を測定し、体積分布の積算値が50%に相当する粒子径を算出することにより行った。
平均繊維径は、SEM画像解析より求めた。
アスペクト比は、SEM画像解析で求めた繊維径で繊維長より算出した。
<電極バインダー樹脂組成物の調製>
撹拌機および窒素導入管を備えた容器に、32.44g(0.3mol)のp-PDと、36.84gのm-BP(0.1mol)と、溶媒として532.7gのNMPとを装入し、溶液の温度を50℃に昇温してp-PDおよびm-BPが溶解するまで撹拌した。溶液の温度を室温まで下げた後、115.33g(0.392mol)のBPDAを約30分かけて投入し、228.3gのNMPをさらに加えて、20時間攪拌して電極バインダー樹脂組成物Aを得た。得られた電極バインダー樹脂組成物は、固形分濃度が18質量%であり、対数粘度は0.89dl/gであった。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、NMPを加えてさらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
93質量部のLiCo1/3Ni1/3Mn1/3O2に、3質量部のポリフッ化ビニリデンをN-メチル-2-ピロリドンに溶解させた溶液と4質量部の導電助剤(電気化学製、デンカブラック)を加えて混合し、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練し正極合材ペーストを得た。このペーストを厚み20μmのアルミニウム箔上に、乾燥後の正極合材質量が単位面積当たり19mg/cm2となるように均一に塗布し、乾燥して正極合材層を形成した後、ローラープレス機により常温プレスして正極を得た。
上記負極を含む電池の電池特性評価を行うためコインセルを作製した。電極には、直径14.5mmΦの負極と、直径13mmΦの正極を用いた。電解液には、エチレンカーボネート(炭酸エチレン)とメチルエチルカーボネート(炭酸メチルエチル)の混合溶媒(体積比3:7混合)にLiPF6を1mol/lの濃度で溶解したものを用い、セパレータに直径16mmΦ、膜厚25μmのポリプロピレン多孔質膜を使用した。
上記セルを25℃にて24時間放置後、測定温度25℃、0.05Cで4.2Vになるまで充電した。その後、0.05Cで2.3Vまで放電するのにかかった時間と、負極活物質の質量から、初回放電容量(単位:mAh/g)を算出した。2サイクル目以降、1Cで4.2Vになるまで充電し、さらに4.2V定電圧で、0.05Cになるまで充電した。その後、1Cで2.3Vまで放電するのにかかった時間と、負極活物質の質量から、2サイクル目以降の放電容量を算出した。上記条件で充放電を繰り返し行い、以下の(式1)にて、100サイクル時の放電容量維持率を算出した。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、SMG-N-HP1-10)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
実施例1で作製したセルを、25℃にて12時間放置後、実施例1と同様の方法で電池評価を行った。結果を表1に示した。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(電気化学製、デンカブラック)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、さらに混練を行い電極ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(ライオン製、ケッチェンブラック)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、さらに混練を行い電極ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、混練を行い電極ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1059、平均粒径5μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(電気化学製、デンカブラック)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(日立化成株式会社製、SMG-N-HP1-10)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(China Steel Chemical社製、SMGP)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
この電極ペーストを、集電体としての銅箔(日本製箔社製圧延銅箔、厚さ:18μm)にアプリケータを用いて塗布し、窒素雰囲気下で350℃、10分間熱処理を行って硬化させて負極を作製した。乾燥後の負極合材質量は単位面積当たり4.4mg/cm2であった。得られた負極を用いて、実施例と同様の方法でコインセルを作成し、電池評価を行った。結果を表1に示した。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されたケイ素酸化物(信越化学工業製、KSC-1064、平均粒径5μm)、炭素粒子(住友ベークライト製、ハードカーボン)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
10質量部のポリイミドを含む電極バインダー樹脂組成物Aと、3質量部の導電助剤(昭和電工製、VGCF-H)を、電池用コンパウンド攪拌機(プライミクス社製、T.K.ハイビスミックス モデル2P-03)を用いて混練した。得られたペーストに、炭素被膜で被覆されていないケイ素酸化物(アルドリッチ製、一酸化ケイ素、平均粒径10μm)、炭素粒子(日立化成株式会社製、MAGD-20)を合計87質量部添加し、さらに混練を行い負極用合材ペーストを調製した。活物質であるケイ素酸化物と炭素粒子の質量比率は30:70とした。
Claims (15)
- ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)およびバインダー(D)を含有する負極活物質層と、集電体と、の積層体を含むリチウムイオン二次電池用負極であって、
該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmであることを特徴とするリチウムイオン二次電池用負極。 - 前記負極活物質層における、前記合金系材料(A)と前記炭素被膜(C)の合計を100質量%としたときの、前記炭素被膜(C)の割合が、3~20質量%である請求項1に記載のリチウムイオン二次電池用負極。
- 前記合金系材料(A)がSiOx(0.5≦x≦1.5)で表されるケイ素酸化物である請求項1または2に記載のリチウムイオン二次電池用負極。
- 前記炭素粒子(B)の平均粒子径D50(B)が、前記合金系材料(A)の平均粒子径D50(A)の2.0~8.0倍である請求項1~3のいずれか1項に記載のリチウムイオン二次電池用負極。
- 前記負極活物質層における、前記合金系材料(A)と前記炭素粒子(B)の合計を100質量%としたときの、合金系材料(A)の含有率が、10~60質量%である請求項1~4のいずれか1項に記載のリチウムイオン二次電池用負極。
- 前記炭素粒子(B)が、扁平状の黒鉛材料が集合または結合してなる請求項1~5のいずれか1項に記載のリチウムイオン二次電池用負極。
- 前記バインダー(D)が、ポリイミドまたはポリアミドイミドである請求項1~6のいずれか1項に記載のリチウムイオン二次電池用負極。
- さらに、導電助剤(C’)を含む請求項1~7のいずれか1項に記載のリチウムイオン二次電池用負極。
- 前記導電助剤(C’)が、アスペクト比が10~1000である炭素繊維を含む請求項8に記載のリチウムイオン二次電池用負極。
- 前記炭素繊維の繊維径が2~1000nmである請求項9に記載のリチウムイオン二次電池用負極。
- 前記炭素繊維が、気相法炭素繊維である請求項9または10に記載のリチウムイオン二次電池用負極。
- 請求項1~11のいずれか1項に記載のリチウムイオン二次電池用負極を含むリチウムイオン二次電池。
- ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)、バインダー用材料(D’)および溶媒(E)を含有するリチウムイオン二次電池用負極用合材ペーストであって、
該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmの範囲を満たすことを特徴とするリチウムイオン二次電池用負極用合材ペースト。 - 前記バインダー用材料(D’)が、ポリイミド、ポリイミドの前駆体およびポリアミドイミドからなる群から選ばれる少なくとも1つであり、前記溶媒(E)が、N-メチル―2-ピロリドンまたはN,N-ジメチルアセトアミドである請求項13に記載のリチウムイオン二次電池用負極用合材ペースト。
- リチウムイオン二次電池用負極用合材ペーストを集電体上に塗布・乾燥する工程を含むリチウムイオン二次電池用負極の製造方法であって、
前記リチウムイオン二次電池用負極用合材ペーストは、ケイ素またはスズを構成元素として含む合金系材料(A)、該合金系材料(A)の表面を被覆する炭素被膜(C)、炭素粒子(B)、バインダー用材料(D’)および溶媒(E)を含有し、該炭素粒子(B)の、窒素ガス吸着法で測定された全細孔容積および平均細孔直径が、各々1.0×10-2~1.0×10-1 cm3/g、および20~50 nmの範囲を満たすことを特徴とする、方法。
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- 2015-02-02 WO PCT/JP2015/000445 patent/WO2015118849A1/ja active Application Filing
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KR20180031769A (ko) * | 2015-09-03 | 2018-03-28 | 가부시키가이샤 히타치세이사쿠쇼 | 리튬 이온 이차 전지 |
KR102075280B1 (ko) * | 2015-09-03 | 2020-02-07 | 가부시키가이샤 히타치세이사쿠쇼 | 리튬 이온 이차 전지 |
CN108701809A (zh) * | 2016-02-17 | 2018-10-23 | 瓦克化学股份公司 | 制备Si/C复合颗粒的方法 |
CN110506350A (zh) * | 2017-04-06 | 2019-11-26 | 株式会社Lg化学 | 二次电池用负极及其制造方法 |
CN110521031A (zh) * | 2017-04-06 | 2019-11-29 | 株式会社Lg化学 | 二次电池用负极及其制造方法 |
US11495785B2 (en) | 2017-04-06 | 2022-11-08 | Lg Energy Solution, Ltd. | Negative electrode for secondary battery and method for producing same |
CN110506350B (zh) * | 2017-04-06 | 2023-02-21 | 株式会社Lg新能源 | 二次电池用负极及其制造方法 |
US11735713B2 (en) | 2017-04-06 | 2023-08-22 | Lg Energy Solution, Ltd. | Negative electrode for secondary battery, and method for producing same |
CN113991059A (zh) * | 2021-11-09 | 2022-01-28 | 河南电池研究院有限公司 | 一种锂离子电池负极极片及其制备方法 |
Also Published As
Publication number | Publication date |
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US10297817B2 (en) | 2019-05-21 |
JP6396343B2 (ja) | 2018-09-26 |
EP3104434B1 (en) | 2019-04-17 |
KR20160104718A (ko) | 2016-09-05 |
EP3104434A1 (en) | 2016-12-14 |
TWI647874B (zh) | 2019-01-11 |
CN105960724B (zh) | 2019-02-15 |
TW201535845A (zh) | 2015-09-16 |
EP3104434A4 (en) | 2017-08-16 |
US20170077501A1 (en) | 2017-03-16 |
KR101898359B1 (ko) | 2018-09-12 |
CN105960724A (zh) | 2016-09-21 |
JPWO2015118849A1 (ja) | 2017-03-23 |
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