WO2021059705A1 - リチウムイオン二次電池用負極およびリチウムイオン二次電池 - Google Patents
リチウムイオン二次電池用負極およびリチウムイオン二次電池 Download PDFInfo
- Publication number
- WO2021059705A1 WO2021059705A1 PCT/JP2020/028213 JP2020028213W WO2021059705A1 WO 2021059705 A1 WO2021059705 A1 WO 2021059705A1 JP 2020028213 W JP2020028213 W JP 2020028213W WO 2021059705 A1 WO2021059705 A1 WO 2021059705A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- negative electrode
- layer
- ion secondary
- secondary battery
- lithium ion
- 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
- 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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
-
- 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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M4/362—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
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/40—Alloys based on alkali metals
- H01M4/405—Alloys based on lithium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present disclosure relates to a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery.
- a lithium ion secondary battery which includes a positive electrode, a negative electrode, and an electrolytic solution and charges and discharges by moving lithium ions between the positive electrode and the negative electrode is widely used.
- Patent Document 1 proposes a lithium ion secondary battery in which a fluorine-containing group is modified on the surface of a negative electrode to improve the affinity with an electrolytic solution.
- lithium-ion secondary batteries have a problem of deterioration in charge / discharge cycle characteristics.
- an object of the present disclosure is to provide a negative electrode for a lithium ion secondary battery and a lithium ion secondary battery capable of improving the charge / discharge cycle characteristics of the lithium ion secondary battery.
- the negative electrode for a lithium ion secondary battery which is one aspect of the present disclosure, includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, and the negative electrode mixture layer is the negative electrode collector.
- the first layer arranged on the electric body and the second layer arranged on the first layer are included, and the second layer contains graphite particles A having a particle internal void ratio of 10% or less.
- the first layer contains graphite particles B having a particle internal void ratio of more than 10%, and the water contact angle of the second layer is 50 ° or less.
- the lithium ion secondary battery according to one aspect of the present disclosure includes the negative electrode for the lithium ion secondary battery.
- the negative electrode for a lithium ion secondary battery which is one aspect of the present disclosure, includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, and the negative electrode mixture layer is the negative electrode collector.
- the first layer arranged on the electric body and the second layer arranged on the first layer are included, and the second layer contains graphite particles A having a particle internal void ratio of 10% or less.
- the first layer contains graphite particles B having a particle internal void ratio of more than 10%, and the water contact angle of the second layer is 50 ° or less.
- graphite particles A having a particle internal porosity of 10% or less are arranged in the second layer on the surface side of the negative electrode, and the water contact angle of the second layer is set to 50 ° or less.
- the pressure loss when the electrolytic solution flows into the negative electrode is reduced.
- the electrolytic solution easily permeates into the negative electrode, and the lithium ion resistance is reduced, so that the charge / discharge cycle characteristics of the lithium ion secondary battery are improved.
- the surface side of the negative electrode is a surface facing the separator and the positive electrode.
- the graphite particles B having a particle internal void ratio of more than 10% are easily crushed during the production of the negative electrode, the adhesiveness between the negative electrode current collector and the graphite particles B is high.
- the particles of the negative electrode active material can be separated from the negative electrode current collector. Since it is suppressed, the charge / discharge cycle characteristics of the lithium ion secondary battery are improved.
- number (1) to numerical value (2) means a numerical value (1) or more and a numerical value (2) or less.
- FIG. 1 is a cross-sectional view of a lithium ion secondary battery which is an example of the embodiment.
- the lithium ion secondary battery 10 shown in FIG. 1 is arranged above and below the wound electrode body 14, the electrolytic solution, and the electrode body 14, in which the positive electrode 11 and the negative electrode 12 are wound around the separator 13.
- the insulating plates 18 and 19 and the battery case 15 for accommodating the above members are provided.
- the battery case 15 is composed of a bottomed cylindrical case body 16 and a sealing body 17 that closes an opening of the case body 16.
- the winding type electrode body 14 instead of the winding type electrode body 14, another form of an electrode body such as a laminated type electrode body in which positive electrodes and negative electrodes are alternately laminated via a separator may be applied.
- examples of the battery case 15 include a metal case such as a cylinder, a square, a coin, and a button, and a resin case (laminated battery) formed by laminating a resin sheet.
- the case body 16 is, for example, a bottomed cylindrical metal container.
- a gasket 28 is provided between the case body 16 and the sealing body 17 to ensure the airtightness inside the battery.
- the case body 16 has, for example, an overhanging portion 22 that supports the sealing body 17 with a part of the side surface overhanging inward.
- the overhanging portion 22 is preferably formed in an annular shape along the circumferential direction of the case body 16, and the sealing body 17 is supported on the upper surface thereof.
- the sealing body 17 has a structure in which a filter 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are laminated in this order from the electrode body 14 side.
- Each member constituting the sealing body 17 has, for example, a disk shape or a ring shape, and each member except the insulating member 25 is electrically connected to each other.
- the lower valve body 24 and the upper valve body 26 are connected to each other at the central portion thereof, and an insulating member 25 is interposed between the peripheral portions thereof.
- the lower valve body 24 When the internal pressure of the lithium ion secondary battery 10 rises due to heat generated by an internal short circuit or the like, for example, the lower valve body 24 is deformed and broken so as to push the upper valve body 26 toward the cap 27 side, and the lower valve body 24 and the upper valve body are broken. The current path between 26 is cut off. When the internal pressure further rises, the upper valve body 26 breaks and gas is discharged from the opening of the cap 27.
- the positive electrode lead 20 attached to the positive electrode 11 extends to the sealing body 17 side through the through hole of the insulating plate 18, and the negative electrode lead 21 attached to the negative electrode 12 is the insulating plate. It extends to the bottom side of the case body 16 through the outside of 19.
- the positive electrode lead 20 is connected to the lower surface of the filter 23, which is the bottom plate of the sealing body 17, by welding or the like, and the cap 27, which is the top plate of the sealing body 17 electrically connected to the filter 23, serves as the positive electrode terminal.
- the negative electrode lead 21 is connected to the inner surface of the bottom of the case body 16 by welding or the like, and the case body 16 serves as a negative electrode terminal.
- the positive electrode 11, the negative electrode 12, the separator 13, and the electrolytic solution constituting the lithium ion secondary battery 10 will be described in detail.
- the positive electrode 11 includes a positive electrode current collector and a positive electrode mixture layer formed on the positive electrode current collector.
- a metal foil stable in the potential range of the positive electrode such as aluminum or an aluminum alloy, a film in which the metal is arranged on the surface layer, or the like can be used.
- the positive electrode mixture layer includes, for example, a positive electrode active material, a binder, and a conductive material.
- the positive electrode mixture layer is preferably formed on both sides of the positive electrode current collector.
- a positive electrode mixture slurry containing a positive electrode active material, a binder, a conductive material, etc. is applied onto the positive electrode current collector, the coating film is dried and rolled, and the positive electrode mixture layer is formed on the positive electrode current collector. It can be manufactured by forming it on both sides.
- the positive electrode active material is composed mainly of a lithium-containing metal composite oxide.
- Metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn. , Ta, W, Ca, Sb, Pb, Bi, Ge and the like can be exemplified.
- An example of a suitable lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.
- Examples of the conductive material contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite.
- Examples of the binder contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, and polyolefins. These resins may be used in combination with carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO) and the like.
- FIG. 2 is a cross-sectional view of a negative electrode which is an example of the embodiment.
- the negative electrode 12 shown in FIG. 2 includes a negative electrode current collector 40 and a negative electrode mixture layer 42 formed on the negative electrode current collector 40.
- a foil of a metal stable in the potential range of the negative electrode such as copper or a copper alloy, a film in which the metal is arranged on the surface layer, or the like can be used.
- the negative electrode mixture layer 42 formed on the negative electrode current collector 40 includes a first layer 44 and a second layer 46.
- the first layer 44 is arranged on the negative electrode current collector 40
- the second layer 46 is arranged on the first layer 44.
- the negative electrode mixture layer 42 is preferably formed on both surfaces of the negative electrode current collector 40.
- the second layer 46 when the second layer 46 is "arranged" on the first layer 44 "above", the second layer 46 may be arranged directly on the first layer 44, or the second layer 46 and the second layer 46 and the second layer 46 may be arranged directly.
- An intermediate layer may be interposed between the layer 44 and the layer 44.
- the first layer 44 contains graphite particles B having a particle internal porosity of more than 10% as a negative electrode active material.
- the second layer 46 contains graphite particles A having a particle internal porosity of 10% or less as a negative electrode active material.
- the internal porosity of the graphite particles A may be 10% or less, preferably 1% to 5%, and more preferably 3% to 5% in terms of improving charge / discharge cycle characteristics. ..
- the internal porosity of the graphite particles B may be more than 10%, preferably 12% to 25%, more preferably 12% to 23%, in terms of being appropriately crushed by the compression step in the negative electrode production. Is.
- Graphite particles A particle internal void ratio of 10% or less is, BET specific surface area of small particles, e.g., in the range of 1.0m 2 /g ⁇ 1.6m 2 / g.
- the graphite particles B having a particle internal porosity of more than 10% are particles having a large BET specific surface area, for example, 3.0 m 2 / g to 20 m 2 / g.
- the BET specific surface area is measured according to the BET method (nitrogen adsorption method) described in JIS R1626.
- FIG. 3 is a schematic view showing a cross section of graphite particles.
- the graphite particle 30 has a closed void 34 that is not connected to the particle surface from the inside of the particle and a void 36 that is connected to the particle surface from the inside of the particle in a cross-sectional view of the graphite particle 30. ..
- the void 34 is hereinafter referred to as an internal void 34.
- the void 36 is hereinafter referred to as an external void 36.
- the internal porosity of the graphite particles is a two-dimensional value obtained from the ratio of the area of the internal voids of the graphite particles to the cross-sectional area of the graphite particles, and is specifically obtained by the following procedure.
- ⁇ Measurement method of internal porosity> The cross section of the negative electrode active material is exposed.
- Examples of the method of exposing the cross section include a method of cutting out a part of the negative electrode and processing it with an ion milling device (for example, IM4000PLUS manufactured by Hitachi High-Tech) to expose the cross section of the negative electrode mixture layer.
- an ion milling device for example, IM4000PLUS manufactured by Hitachi High-Tech
- the cross-sectional image obtained as described above is taken into a computer and binarized using image analysis software (for example, ImageJ manufactured by the American National Institutes of Health) to make the cross-sectional image of the particles in the cross-sectional image black.
- image analysis software for example, ImageJ manufactured by the American National Institutes of Health
- a binarized image obtained by converting the voids existing in the cross section of the particle into white is obtained.
- the area of the graphite particle cross section and the area of the internal voids existing in the graphite particle cross section are calculated.
- the area of the cross section of the graphite particles refers to the area of the region surrounded by the outer periphery of the graphite particles, that is, the area of the entire cross section of the graphite particles.
- the amount of graphite particles B contained in the first layer 44 is preferably larger than that of the graphite particles B contained in the second layer 46 in terms of improving charge / discharge cycle characteristics, and the total amount of graphite particles B in the negative electrode mixture layer 42. It is preferably in the range of 50% by mass to 90% by mass.
- the first layer 44 may contain graphite particles A having a particle internal void ratio of 10% or less as the negative electrode active material, but the graphite particles A in the first layer 44 can be improved in terms of improving charge / discharge cycle characteristics.
- the content is preferably 10% by mass or less with respect to the total amount of graphite particles A in the negative electrode mixture layer 42.
- the amount of graphite particles A contained in the second layer 46 is preferably larger than that of the graphite particles A contained in the first layer 44 in terms of improving charge / discharge cycle characteristics, and the total amount of graphite particles A in the negative electrode mixture layer 42. It is preferably in the range of 40% by mass to 100% by mass.
- the second layer 46 may contain graphite particles B as the negative electrode active material, but the content of the graphite particles B in the second layer 46 is in the negative electrode mixture layer 42 in terms of improving charge / discharge cycle characteristics. It is preferably 50% by mass or less with respect to the total amount of graphite particles B in the above.
- Graphite particles A and B are produced, for example, as follows.
- ⁇ Graphite particles A having an internal porosity of 10% or less> For example, coke (precursor), which is the main raw material, is crushed to a predetermined size, and the coke (precursor), which is the main raw material, is agglomerated with a binder, fired at a temperature of 2600 ° C. or higher, graphitized, and then sieved. A graphite particle A having a desired size is obtained.
- the internal porosity can be adjusted to 10% or less depending on the particle size of the precursor after pulverization, the particle size of the precursor in an agglomerated state, and the like.
- the average particle size (median diameter D50) of the precursor after pulverization is preferably in the range of 12 ⁇ m to 20 ⁇ m.
- coke precursor
- a binder aggregated with a binder
- the graphitized block-shaped molded product is pulverized and sieved to obtain graphite particles B having a desired size.
- the internal porosity can be adjusted to more than 10% depending on the amount of volatile components added to the block-shaped molded product.
- the binder When a part of the binder added to coke (precursor) volatilizes during firing, the binder can be used as a volatile component. Pitch is exemplified as such a binder.
- the graphite particles A and B used in the present embodiment are not particularly limited to natural graphite, artificial graphite and the like, but artificial graphite is preferable in terms of ease of adjusting the internal porosity and the like.
- the surface spacing (d 002 ) of the (002) planes of the graphite particles A and B used in the present embodiment by the X-ray wide-angle diffraction method is preferably, for example, 0.3354 nm or more, and is 0.3357 nm or more. Is more preferable, and it is preferably less than 0.340 nm, and more preferably 0.338 nm or less.
- the crystallite size (Lc (002)) of the graphite particles A and B used in the present embodiment determined by the X-ray diffraction method is, for example, preferably 5 nm or more, and more preferably 10 nm or more. Further, it is preferably 300 nm or less, and more preferably 200 nm or less.
- the average particle size of the graphite particles A and B is not particularly limited, but is, for example, 1 ⁇ m to 30 ⁇ m.
- the average particle size means a volume average particle size (Dv50) at which the integrated volume value is 50% in the particle size distribution measured by the laser diffraction / scattering method.
- the water contact angle of the second layer 46 may be 50 ° or less, but preferably 40 ° or less, in terms of facilitating the penetration of the electrolytic solution into the negative electrode 12 and improving the charge / discharge cycle characteristics. More preferably, it is 35 ° or less.
- the water contact angle of the second layer 46 changes depending on, for example, the volume ratio of the graphite particles A in the second layer 46, the packing density of the negative electrode mixture layer 42 (or the filling density of the second layer 46), and the like.
- the volume ratio of the graphite particles A in the second layer 46 to the total volume of the second layer 46 is preferably 29% by volume or more in terms of making the water contact angle of the second layer 46 50 ° or less. , 50% by volume or more is more preferable.
- the filling density of the negative electrode mixture layer 42 (or the filling density of the second layer 46) is such that the water contact angle of the second layer 46 is 50 ° or less, for example, 1.50 g / cm 3 to 1.
- the range of 65 g / cm 3 is preferable, and the range of 1.4 g / cm 3 to 1.5 g / cm 3 is more preferable.
- the negative electrode mixture layer 42 may contain an alloying material as the negative electrode active material. By including the alloying material, it is possible to increase the capacity of the lithium ion secondary battery.
- the alloying material may be contained in the first layer 44 and the second layer 46 in the same amount or in a larger amount in either of them, but suppresses deterioration of the charge / discharge cycle characteristics of the lithium ion secondary battery.
- the second layer 46 contains more than the first layer 44, and the content of the alloying material in the second layer 46 is the total amount of the alloying material in the negative electrode mixture layer 42. On the other hand, it is preferably in the range of 75% by mass to 100% by mass.
- the content of the alloying material is the total amount of the negative electrode active material in the negative electrode mixture layer 42. It is preferably 15% by mass or less.
- the lower limit of the content of the alloying material is 5% by mass or more with respect to the total amount of the negative electrode active material in the negative electrode mixture layer 42 in terms of increasing the capacity of the lithium ion secondary battery. It is preferably 8% by mass or more, and more preferably 8% by mass or more.
- the alloying material is composed of an element that alloys with lithium, a compound that contains an element that alloys with lithium, or both.
- the element that alloys with lithium that can be applied to the negative electrode active material include Al, Ga, In, Si, Ge, Sn, Pb, As, Sb, and Bi. Among them, Si and Sn are preferable, and Si is particularly preferable, from the viewpoint of increasing the capacity.
- Si-containing compound examples include a silicon oxide phase, a Si-containing compound dispersed in the silicon oxide phase, a lithium silicate phase, and a Si-containing compound dispersed in the lithium silicate phase.
- the silicon oxide phase and the compound containing Si dispersed in the silicon oxide phase are hereinafter referred to as “SiO”.
- the lithium silicate phase and the compound containing Si dispersed in the lithium silicate phase are hereinafter referred to as “LSX”.
- a conductive layer made of a highly conductive material may be formed on the surface of the SiO and LSX particles.
- An example of a suitable conductive layer is a carbon coating made of a carbon material.
- the carbon film is composed of, for example, carbon black, acetylene black, ketjen black, graphite, and a mixture of two or more of these.
- Examples of the method of carbon-coating the particle surfaces of SiO and LSX include a CVD method using acetylene, methane, etc., a method of mixing coal pitch, petroleum pitch, phenol resin, etc. with SiO, LSX particles, and performing heat treatment. it can.
- a carbon film may be formed by fixing carbon powder such as carbon black to the particle surface using a binder.
- a suitable SiO has a sea-island structure in which fine Si particles are substantially uniformly dispersed in an amorphous silicon oxide phase, and is represented by the general formula SiO x (0.5 ⁇ x ⁇ 1.6).
- the content of Si particles is preferably 35 to 75% by mass with respect to the total mass of SiO, from the viewpoint of achieving both battery capacity and cycle characteristics.
- the average particle size of the Si particles dispersed in the silicon oxide phase is generally 500 nm or less, preferably 200 nm or less, and more preferably 50 nm or less before charging / discharging. After charging and discharging, 400 nm or less is preferable, and 100 nm or less is more preferable. By making the Si particles finer, the volume change during charging and discharging becomes smaller and the cycle characteristics are improved.
- the average particle size of the Si particles is measured by observing the cross section of SiO using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and specifically, the longest diameter of 100 Si particles. Obtained as an average value.
- the silicon oxide phase is composed of, for example, a set of particles finer than Si particles.
- a suitable LSX has a sea-island structure in which fine Si particles are substantially uniformly dispersed in a lithium silicate phase represented by the general formula Li 2z SiO (2 + z) (0 ⁇ z ⁇ 2).
- the content of Si particles is preferably 35 to 75% by mass with respect to the total mass of LSX, as in the case of SiO.
- the average particle size of the Si particles is generally 500 nm or less, preferably 200 nm or less, and more preferably 50 nm or less before charging / discharging.
- the lithium silicate phase is composed of, for example, an aggregate of particles finer than Si particles.
- SiO can be produced by the following steps. (1) Si and silicon oxide are mixed at a weight ratio of, for example, 20:80 to 95: 5 to prepare a mixture. (2) At least before or after the preparation of the above mixture, Si and silicon oxide are pulverized into fine particles by, for example, a ball mill. (3) The pulverized mixture is heat-treated at 600 to 1000 ° C., for example, in an inert atmosphere.
- LSX can be produced by using lithium silicate instead of silicon oxide.
- the negative electrode mixture layer 42 preferably contains a binder.
- the binder is, for example, a fluororesin such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, polyolefin, polyacrylic acid (hereinafter referred to as PAA) or a salt thereof. , Styrene butadiene rubber, carboxymethyl cellulose (hereinafter, CMC) or a salt thereof and the like.
- PTFE polytetrafluoroethylene
- PVDF polyvinylidene fluoride
- PAN polyacrylonitrile
- PAA polyimide
- PAA polyacrylic acid
- CMC carboxymethyl cellulose
- the content of the binder in the negative electrode mixture layer 42 is, for example, preferably 0.5% by mass to 10% by mass, more preferably 1% by mass to 5% by mass, based on the total amount of the negative electrode mixture layer 42.
- styrene-butadiene rubber is a substance that affects the water contact angle of the second layer 46
- the water contact angle of the second layer 46 is set to 50 ° or less. In terms of points, it is preferable that the first layer 44 contains more than the second layer 46.
- the negative electrode mixture layer 42 preferably contains fibrous carbon. Since the fibrous carbon is contained, a good conductive path is formed in the negative electrode mixture layer 42, and the charge / discharge cycle characteristics can be improved more effectively.
- the fibrous carbon may be contained in the first layer 44 and the second layer 46 in the same amount, or may be contained in a large amount in either of them. However, when the alloying material is contained more in the second layer 46 than in the first layer 44, the fibrous carbon is more than the first layer 44 in that it maintains a conductive path to the alloying material. It is preferable that the two layers 46 contain a large amount.
- fibrous carbon examples include carbon nanotubes (CNT) and carbon nanofibers.
- the CNTs may be not only single-walled CNTs, but also double-walled CNTs, multi-walled CNTs, and mixtures thereof. Further, the CNT may be a vapor-grown carbon fiber.
- the fibrous carbon has, for example, a diameter of 2 nm to 20 ⁇ m and a total length of 0.03 ⁇ m to 500 ⁇ m.
- the content of fibrous carbon in the negative electrode mixture layer 42 is, for example, preferably 0.01% by mass to 5% by mass, more preferably 0.5% by mass to 3% by mass, based on the total amount of the negative electrode mixture layer 42. preferable.
- the thickness of the negative electrode mixture layer 42 is, for example, 30 ⁇ m to 100 ⁇ m or 50 ⁇ m to 80 ⁇ m on one side of the negative electrode current collector 40.
- the thicknesses of the first layer 44 and the second layer 46 may be the same or different from each other, but the thickness of the second layer 46 is easy to obtain the effect of improving the charge / discharge cycle characteristics. Is preferably 1/3 or more, more preferably 1/3 to 1/2 with respect to the thickness of the negative electrode mixture layer 42.
- an intermediate layer may be provided between the first layer 44 and the second layer 46.
- the intermediate layer may contain the above-mentioned graphite particles A, graphite particles B, and an alloying material, or may contain other conventionally known negative electrode active materials and the like.
- the intermediate layer may be designed within a range that does not impair the effects of the present disclosure.
- the negative electrode 12 is manufactured by, for example, the following method.
- a first negative electrode mixture slurry for the first layer 44 containing graphite particles B, a binder, and the like is prepared.
- a second negative electrode mixture slurry for the second layer 46 containing graphite particles A, a binder and the like is prepared.
- the first negative electrode mixture slurry is applied onto the negative electrode current collector 40, and the coating film is dried to form the first layer 44 on the negative electrode current collector 40.
- the second negative electrode mixture slurry is applied onto the first layer 44, the coating film is dried to form the second layer 46 on the first layer 44, and then the first layer 44 and the second layer 46 are formed. Compress. In this way, the negative electrode 12 in which the negative electrode mixture layer 42 including the first layer 44 and the second layer 46 is formed on the negative electrode current collector 40 is obtained.
- a porous sheet having ion permeability and insulating property is used as the separator 13.
- the porous sheet include a microporous thin film, a woven fabric, and a non-woven fabric.
- olefin resin such as polyethylene, polypropylene, a copolymer containing at least one of ethylene and propylene, cellulose and the like are suitable.
- the separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.
- the electrolytic solution contains a solvent and an electrolyte salt.
- the electrolyte salt for example, lithium salts such as LiBF 4 and LiPF 6 are used.
- Solvents include, for example, esters such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propionate (MP), and ethers. , Nitriles, amides, and mixed solvents of two or more of these are used.
- the non-aqueous solvent may contain a halogen substituent in which at least a part of hydrogen in these solvents is replaced with a halogen atom such as fluorine.
- halogen substituent examples include a fluorinated cyclic carbonate such as fluoroethylene carbonate (FEC), a fluorinated chain carbonate, and a fluorinated chain carboxylic acid ester such as methyl fluoropropionate (FMP).
- FEC fluoroethylene carbonate
- FMP fluorinated chain carboxylic acid ester
- Lithium cobalt oxide as the positive electrode active material is mixed so as to be 90 parts by mass, graphite as the conductive material is 5 parts by mass, and polyvinylidene fluoride powder as the binder is 5 parts by mass, and further, N-methyl-2-pyrrolidone is added.
- An appropriate amount of (NMP) was added to prepare a positive electrode mixture slurry. This slurry is applied to both sides of a current collector made of aluminum foil (thickness 15 ⁇ m) by the doctor blade method, the coating film is dried, and then the coating film is compressed by a rolling roller to form positive electrodes on both sides of the positive electrode current collector. A positive electrode on which the active material layer was formed was produced.
- the first negative electrode mixture slurry was applied to both sides of the negative electrode current collector made of copper foil, and the coating film was dried to form the first layer on both sides of the negative electrode current collector.
- the second negative electrode mixture slurry was applied onto the first layer formed on both sides of the negative electrode current collector, and the coating film was dried to form the second layer.
- the coating film was rolled using a roller to prepare a negative electrode in which negative electrode mixture layers including the first layer and the second layer were formed on both sides of the negative electrode current collector.
- the density of the negative electrode mixture layer is 1.6 g / cc, and the thickness ratio of the second layer: the first layer is 1: 1.
- the water contact angle of the second layer of the prepared negative electrode was measured and found to be 31 °. Since the measurement method is as described above, it will be omitted.
- the internal porosities of the graphite particles A and B were measured and found to be 5% and 22%, respectively.
- the following examples and comparative examples also had the same particle internal porosity. Since the measurement method is as described above, it will be omitted.
- the volume ratio of the graphite particles A in the second layer was 86% by volume, and the volume ratio of the Si compound in the second layer was 14% by volume with respect to the total volume of the second layer. Since the graphite particles used and the Si compound are equivalent, the mass of the graphite particles and the Si compound material charged into the negative electrode mixture slurry directly corresponds to the volume of the graphite particles and the Si compound material. That is, the above volume% is synonymous with mass%.
- Electrolytic solution 1% by mass of vinylene carbonate (VC) was added to a mixed solvent in which ethylene carbonate (EC), fluorinated ethylene carbonate (FEC), and diethyl carbonate (DEC) were mixed at a volume ratio of 27: 3: 70.
- An electrolytic solution was prepared by dissolving LiPF 6 at a ratio of 1.2 mol / L.
- Test cell The positive electrode and the negative electrode were laminated so as to face each other via a separator, and wound around the positive electrode to prepare an electrode body. Next, the electrode body and the electrolytic solution were housed in a bottomed cylindrical battery case body, the electrolytic solution was injected, and then the opening of the battery case body was sealed with a gasket and a sealing body to prepare a test cell. ..
- Example 2 In the preparation of the second negative electrode mixture slurry, a mixture of graphite particles A in an amount of 29 parts by mass, graphite particles B in an amount of 57 parts by mass, and a Si compound in an amount of 14 parts by mass was used as the negative electrode active material.
- a test cell was prepared in the same manner as in Example 1.
- the water contact angle of the second layer in the prepared negative electrode was 50 °. Further, the volume ratio of the graphite particles A in the second layer is 29% by volume, and the volume ratio of the graphite particles B in the second layer is 57% by volume with respect to the total volume of the second layer. The volume ratio of the Si compound in the layer was 14% by volume.
- Example 3 Examples in the preparation of the second negative electrode mixture slurry, except that these were mixed so that the mass ratio of the negative electrode active material: CMC was 100: 1 (that is, styrene-butadiene rubber was not added). A test cell was prepared in the same manner as in 1. The water contact angle of the second layer in the prepared negative electrode was 28 °.
- Example 4 A test cell was prepared in the same manner as in Example 1 except that the thickness ratio of the second layer: the first layer was 1: 2. The water contact angle of the second layer in the prepared negative electrode was 31 °.
- Example 5 In the preparation of the second negative electrode mixture slurry, the same as in Example 1 except that the negative electrode active material: CMC: styrene-butadiene rubber: CNT was mixed so as to have a mass ratio of 100: 1: 1: 1. A test cell was prepared in. The water contact angle of the second layer in the prepared negative electrode was 31 °.
- ⁇ Comparative example 1> A mixture of graphite particles B in an amount of 93 parts by mass and Si compound (SiO) in an amount of 7 parts by mass is used as a negative electrode active material, and the mass ratio of negative electrode active material: CMC: styrene-butadiene rubber is 100: 1: 1. These were mixed so as to be, and an appropriate amount of water was added to prepare a negative electrode mixture slurry. Negative electrode mixture slurry is applied to both sides of the negative electrode current collector made of copper foil, the coating film is dried, and then the coating film is rolled using a roller to form negative electrode mixture layers on both sides of the negative electrode current collector. A negative electrode in which the above was formed was produced.
- Example 2 Using this negative electrode, a test cell was prepared in the same manner as in Example 1.
- the water contact angle of the negative electrode mixture layer in the prepared negative electrode was 119 °.
- the volume ratio of the Si compound in the negative electrode mixture layer to the total volume of the negative electrode mixture layer was 7% by volume.
- the water contact angle of the second layer in the prepared negative electrode was 119 °.
- the volume ratio of the graphite particles A in the first layer was 86% by volume with respect to the total volume of the first layer, and the volume ratio of the Si compound in the first layer was 14% by volume.
- the water contact angle of the second layer in the prepared negative electrode was 110 °.
- the volume ratio of the Si compound in the second layer to the total volume of the second layer was 14% by volume.
- the negative electrode active material is a mixture in which graphite particles A are 21.5 parts by mass, graphite particles B are 64.5 parts by mass, and Si compound (SiO) is 14 parts by mass.
- a test cell was prepared in the same manner as in Example 1.
- the water contact angle of the second layer in the prepared negative electrode was 103 °.
- the volume ratio of the graphite particles A in the second layer was 21.5% with respect to the total volume of the second layer, and the volume ratio of the Si compound in the second layer was 14% by volume.
- Capacity retention rate (discharge capacity in the 200th cycle / discharge capacity in the 4th cycle) x 100 Table 1 shows the evaluation results (capacity retention rate in 200 cycles) of the test cells of Examples 1 to 5 and Comparative Examples 1 to 4.
- test cells of Examples 1 to 5 had a higher capacity retention rate in the charge / discharge cycle than the test cells of Comparative Examples 1 to 4, and the charge / discharge cycle characteristics were improved.
- the second layer contains graphite particles A having a particle internal void ratio of 10% or less
- the first layer contains graphite particles B having a particle internal void ratio of more than 10%
- the second layer It can be said that the charge / discharge cycle characteristics of the lithium ion secondary battery were improved by using the negative electrode having a water contact angle of 50 ° or less.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Description
正極11は、正極集電体と、正極集電体上に形成された正極合材層とを備える。正極集電体には、アルミニウム、アルミニウム合金などの正極の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。正極合材層は、例えば正極活物質、結着材、導電材を含む。正極合材層は、正極集電体の両面に形成されることが好ましい。正極は、例えば正極活物質、結着材、導電材等を含む正極合材スラリーを正極集電体上に塗布し、塗膜を乾燥、圧延して、正極合材層を正極集電体の両面に形成することにより製造できる。
図2は、実施形態の一例である負極の断面図である。図2に示す負極12は、負極集電体40と、負極集電体40上に形成された負極合材層42とを備える。負極集電体40には、例えば、銅、銅合金などの負極の電位範囲で安定な金属の箔、当該金属を表層に配置したフィルム等を用いることができる。
(1)負極活物質の断面を露出させる。断面を露出させる方法としては、例えば、負極の一部を切り取り、イオンミリング装置(例えば、日立ハイテク社製、IM4000PLUS)で加工し、負極合材層の断面を露出させる方法が挙げられる。
(2)走査型電子顕微鏡を用いて、上記露出させた負極合材層の断面の反射電子像を撮影する。反射電子像を撮影する際の倍率は、3千倍から5千倍である。
(3)上記により得られた断面像をコンピュータに取り込み、画像解析ソフト(例えば、アメリカ国立衛生研究所製、ImageJ)を用いて二値化処理を行い、断面像内の粒子断面を黒色とし、粒子断面に存在する空隙を白色として変換した二値化処理画像を得る。
(4)二値化処理画像から、黒鉛粒子断面の面積、及び当該黒鉛粒子断面に存在する内部空隙の面積を算出する。ここで、黒鉛粒子断面の面積とは、黒鉛粒子の外周で囲まれた領域の面積、すなわち、黒鉛粒子の断面部分全ての面積を指している。また、黒鉛粒子断面に存在する空隙のうち幅が3μm以下の空隙については、画像解析上、内部空隙か外部空隙かの判別が困難となる場合があるため、幅が3μm以下の空隙は内部空隙としてもよい。そして、算出した黒鉛粒子断面の面積及び黒鉛粒子断面の内部空隙の面積から、黒鉛粒子の内部空隙率(黒鉛粒子の内部空隙率=黒鉛粒子断面の内部空隙の面積×100/黒鉛粒断面の面積)を算出する。黒鉛粒子の内部空隙率は、黒鉛粒子10個の平均値とする。
例えば、主原料となるコークス(前駆体)を所定サイズに粉砕し、それらを結着材で凝集させた状態で、2600℃以上の温度で焼成し、黒鉛化させた後、篩い分けることで、所望のサイズの黒鉛粒子Aを得る。ここで、粉砕後の前駆体の粒径や凝集させた状態の前駆体の粒径等によって、内部空隙率を10%以下に調整することができる。例えば、粉砕後の前駆体の平均粒径(メジアン径D50)は、12μm~20μmの範囲であることが好ましい。
例えば、主原料となるコークス(前駆体)を所定サイズに粉砕し、それらを結着材で凝集した後、さらにブロック状に加圧成形した状態で、2600℃以上の温度で焼成し、黒鉛化させる。黒鉛化後のブロック状の成形体を粉砕し、篩い分けることで、所望のサイズの黒鉛粒子Bを得る。ブロック状の成形体に添加される揮発成分の量によって、内部空隙率を10%超に調整することができる。
(1)Si及び酸化ケイ素を、例えば20:80~95:5の重量比で混合して混合物を作製する。
(2)少なくとも上記混合物の作製前又は作製後に、例えばボールミルによりSi及び酸化ケイ素を粉砕して微粒子化する。
(3)粉砕された混合物を、例えば不活性雰囲気中、600~1000℃で熱処理する。
セパレータ13は、イオン透過性および絶縁性を有する多孔性シートが用いられる。多孔性シートの具体例としては、微多孔薄膜、織布、不織布等が挙げられる。セパレータ13の材質としては、ポリエチレン、ポリプロピレン、エチレンおよびプロピレンの少なくとも一方を含む共重合体等のオレフィン系樹脂、セルロースなどが好適である。セパレータ13は、単層構造、積層構造のいずれであってもよい。セパレータ13の表面には、耐熱層などが形成されていてもよい。
電解液は、溶媒と、電解質塩とを含む。電解質塩には、例えば、LiBF4、LiPF6等のリチウム塩が用いられる。溶媒には、例えば、エチレンカーボネート(EC)、プロピレンカーボネート(PC)、ジメチルカーボネート(DMC)、エチルメチルカーボネート(EMC)、ジエチルカーボネート(DEC)、プロピオン酸メチル(MP)等のエステル類、エーテル類、ニトリル類、アミド類、およびこれらの2種以上の混合溶媒などが用いられる。非水溶媒は、上記これらの溶媒の水素の少なくとも一部をフッ素等のハロゲン原子で置換したハロゲン置換体を含有していてもよい。
[正極]
正極活物質としてのコバルト酸リチウムが90質量部、導電材としての黒鉛が5質量部、結着材としてのポリフッ化ビニリデン粉末が5質量部となるよう混合し、さらにN-メチル-2-ピロリドン(NMP)を適量加えて、正極合材スラリーを調製した。このスラリーをアルミニウム箔(厚さ15μm)からなる集電体の両面にドクターブレード法により塗布し、塗膜を乾燥した後、圧延ローラーにより塗膜を圧縮して、正極集電体の両面に正極活物質層が形成された正極を作製した。
コークスを平均粒径(メジアン径D50)が15μmとなるまで粉砕し、粉砕したコークスに結着材としてのピッチを添加し、コークスを平均粒径(メジアン径D50)が17μmとなるまで凝集させた。この凝集物を2800℃の温度で焼成して黒鉛化した後、250メッシュの篩いを用いて、篩い分けを行い、平均粒径(メジアン径D50)が26μmの黒鉛粒子Aを得た。
コークスを平均粒径(メジアン径D50)が15μmとなるまで粉砕し、粉砕したコークスに結着材としてのピッチを添加して凝集させた後、さらに等方的な圧力で1.6g/cm3~1.9g/cm3の密度を有するブロック状の成形体とした。このブロック状の成形体を2800℃の温度で焼成して黒鉛化した後、ブロック状の成形体を粉砕し、250メッシュの篩いを用いて、篩い分けを行い、平均粒径(メジアン径D50)が19μmの黒鉛粒子Bを得た。
黒鉛粒子Bを負極活物質として、黒鉛粒子B:CMC:スチレンブタジエンゴムの質量比が、100:1:1となるようにこれらを混合し、水を適量加えて、第1層用の第1負極合材スラリーを調整した。また、黒鉛粒子Aが86質量部、Si化合物(SiO)が14質量部となるように混合した混合物を負極活物質として、負極活物質:CMC:スチレンブタジエンゴムの質量比が、100:1:1となるようにこれらを混合し、水を適量加えて、第2層用の第2負極合材スラリーを調整した。
エチレンカーボネート(EC)と、フッ化エチレンカーボネート(FEC)と、ジエチルカーボネート(DEC)とを、27:3:70の体積比で混合した混合溶媒にビニレンカーボネート(VC)を1質量%添加し、LiPF6を1.2モル/Lの割合で溶解させて電解液を調製した。
正極と、負極とを、セパレータを介して互いに対向するように積層し、これを巻回して、電極体を作製した。次いで、電極体及び上記電解液を有底円筒形状の電池ケース本体に収容し、上記電解液を注入した後、ガスケット及び封口体により電池ケース本体の開口部を封口して、試験セルを作製した。
第2負極合材スラリーの調製において、黒鉛粒子Aが29質量部、黒鉛粒子Bが57質量部、Si化合物が14質量部となるように混合した混合物を負極活物質として用いたこと以外は、実施例1と同様に試験セルを作製した。
第2負極合材スラリーの調製において、負極活物質:CMCの質量比が、100:1となるようにこれらを混合したこと(すなわち、スチレンブタジエンゴムを添加しなかったこと)以外は、実施例1と同様に試験セルを作製した。作製した負極における第2層の水接触角は28°であった。
第2層:第1層の厚み比を1:2にしたこと以外は、実施例1と同様に試験セルを作製した。作製した負極における第2層の水接触角は31°であった。
第2負極合材スラリーの調製において、負極活物質:CMC:スチレンブタジエンゴム:CNTの質量比が、100:1:1:1となるようにこれらを混合したこと以外は、実施例1と同様に試験セルを作製した。作製した負極における第2層の水接触角は31°であった。
黒鉛粒子Bが93質量部、Si化合物(SiO)が7質量部となるように混合した混合物を負極活物質として、負極活物質:CMC:スチレンブタジエンゴムの質量比が、100:1:1となるようにこれらを混合し、水を適量加えて、負極合材スラリーを調整した。銅箔からなる負極集電体の両面に、負極合材スラリーを塗布し、塗膜を乾燥させた後、ローラーを用いて塗膜を圧延して、負極集電体の両面に負極合材層が形成された負極を作製した。この負極を用いて、実施例1と同様に試験セルを作製した。作製した負極における負極合材層の水接触角は119°であった。負極合材層の総体積に対して、負極合材層内のSi化合物の体積比率は、7体積%であった。
第1負極合材スラリーの調製において、黒鉛粒子Aが86質量部、Si化合物(SiO)が14質量部となるように混合した混合物を負極活物質としたこと、第2負極合材スラリーの調製において、黒鉛粒子Bを負極活物質としたこと以外は、実施例1と同様に試験セルを作製した。
第2負極合材スラリーの調製において、黒鉛粒子Bが86質量部、Si化合物(SiO)が14質量部となるように混合した混合物を負極活物質としたこと以外は、実施例1と同様に試験セルを作製した。
第2負極合材スラリーの調製において、黒鉛粒子Aが21.5質量部、黒鉛粒子Bが64.5質量部、Si化合物(SiO)が14質量部となるように混合した混合物を負極活物質としたこと以外は、実施例1と同様に試験セルを作製した。
試験セルを、25℃の温度環境下、0.5Cの定電流で電池電圧が4.2Vになるまで定電流で充電した後、4.2Vで電流値が1/50Cになるまで定電圧で充電した。その後、1.0Cの定電流で電池電圧が2.5Vになるまで定電流放電を行った。また、この充放電を200サイクル行い、下記の式に基づいて、充放電サイクルにおける容量維持率を求めた。
表1に、実施例1~5及び比較例1~4の試験セルについての評価結果(200サイクルにおける容量維持率)を示す。
11 正極
12 負極
13 セパレータ
14 電極体
15 電池ケース
16 ケース本体
17 封口体
18 絶縁板
18,19 絶縁板
20 正極リード
21 負極リード
22 張り出し部
23 フィルタ
24 下弁体
25 絶縁部材
26 上弁体
27 キャップ
28 ガスケット
30 黒鉛粒子
34 内部空隙
36 外部空隙
40 負極集電体
42 負極合材層
44 第1層
46 第2層
Claims (8)
- 負極集電体と、前記負極集電体上に形成された負極合材層とを備え、
前記負極合材層は、前記負極集電体上に配置された第1層と、前記第1層上に配置された第2層と、含み、
前記第2層は、粒子内部空隙率が10%以下である黒鉛粒子Aを含み、前記第1層は、粒子内部空隙率が10%超である黒鉛粒子Bを含み、
前記第2層の水接触角は50°以下である、リチウムイオン二次電池用負極。 - 前記負極合材層は、リチウムと合金化する合金化材料を含み、
前記合金化材料は、前記第1層より、前記第2層に多く含まれる、請求項1に記載のリチウムイオン二次電池用負極。 - 前記第2層の総体積に対する前記第2層内の前記黒鉛粒子Aの体積比率は、29体積%以上である、請求項1又は2に記載のリチウムイオン二次電池用負極。
- 前記負極合材層は、繊維状炭素を含み、
前記繊維状炭素は、前記第1層より、前記第2層に多く含まれる、請求項2に記載のリチウムイオン二次電池用負極。 - 前記負極合材層は、スチレンブタジエンゴムを含み、
前記スチレンブタジエンゴムは、前記第2層より、前記第1層に多く含まれる、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。 - 前記スチレンブタジエンゴムは、前記負極集電体側半分の領域に、前記負極合材層に含まれるすべての前記スチレンブタジエンゴムの90質量%以上100質量%が含まれている、請求項5に記載のリチウムイオン二次電池用負極。
- 前記第2層の厚みは、前記負極合材層の厚みに対して1/3以上である、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。
- 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を備える、リチウムイオン二次電池。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17/763,021 US20220344659A1 (en) | 2019-09-27 | 2020-07-21 | Negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
EP20869072.7A EP4037015A4 (en) | 2019-09-27 | 2020-07-21 | NEGATIVE ELECTRODE FOR SECONDARY LITHIUM-ION BATTERY AND SECONDARY LITHIUM-ION BATTERY |
CN202080066245.8A CN114424360B (zh) | 2019-09-27 | 2020-07-21 | 锂离子二次电池用负极和锂离子二次电池 |
JP2021548377A JPWO2021059705A1 (ja) | 2019-09-27 | 2020-07-21 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2019177955 | 2019-09-27 | ||
JP2019-177955 | 2019-09-27 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2021059705A1 true WO2021059705A1 (ja) | 2021-04-01 |
Family
ID=75166940
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2020/028213 WO2021059705A1 (ja) | 2019-09-27 | 2020-07-21 | リチウムイオン二次電池用負極およびリチウムイオン二次電池 |
Country Status (5)
Country | Link |
---|---|
US (1) | US20220344659A1 (ja) |
EP (1) | EP4037015A4 (ja) |
JP (1) | JPWO2021059705A1 (ja) |
CN (1) | CN114424360B (ja) |
WO (1) | WO2021059705A1 (ja) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20210202932A1 (en) * | 2019-12-26 | 2021-07-01 | Panasonic Corporation | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery |
US20210202933A1 (en) * | 2019-12-26 | 2021-07-01 | Panasonic Corporation | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery |
CN113346043A (zh) * | 2021-06-04 | 2021-09-03 | 江西安驰新能源科技有限公司 | 一种低温锂离子电池正极极片及其制备方法,锂离子电池 |
US20220216475A1 (en) * | 2019-04-24 | 2022-07-07 | Sanyo Electric Co., Ltd. | Nonaqueous electrolyte secondary battery |
WO2024106074A1 (ja) * | 2022-11-17 | 2024-05-23 | パナソニックIpマネジメント株式会社 | 非水電解質二次電池 |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH08287952A (ja) * | 1995-04-11 | 1996-11-01 | Matsushita Electric Ind Co Ltd | 非水電解液二次電池 |
JP2009064574A (ja) * | 2007-09-04 | 2009-03-26 | Nec Tokin Corp | リチウムイオン二次電池 |
JP2012094261A (ja) * | 2010-10-25 | 2012-05-17 | Panasonic Corp | 非水系二次電池用負極板およびこれを用いた非水系二次電池 |
JP2017041407A (ja) | 2015-08-21 | 2017-02-23 | 日産自動車株式会社 | リチウムイオン二次電池 |
JP2018523912A (ja) * | 2015-12-23 | 2018-08-23 | エルジー・ケム・リミテッド | リチウム二次電池用負極活物質及びこれを含むリチウム二次電池用負極 |
WO2019239652A1 (ja) * | 2018-06-15 | 2019-12-19 | 三洋電機株式会社 | 非水電解質二次電池 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4040381B2 (ja) * | 2002-07-30 | 2008-01-30 | Jfeケミカル株式会社 | 複合黒鉛質粒子およびその製造方法ならびにリチウムイオン二次電池用負極およびリチウムイオン二次電池 |
JP5458689B2 (ja) * | 2008-06-25 | 2014-04-02 | 三菱化学株式会社 | 非水系二次電池用複合黒鉛粒子、それを含有する負極材料、負極及び非水系二次電池 |
KR101057162B1 (ko) * | 2008-12-01 | 2011-08-16 | 삼성에스디아이 주식회사 | 음극활물질, 이를 구비하는 음극 및 리튬이차전지 |
JP6154380B2 (ja) * | 2012-08-06 | 2017-06-28 | 昭和電工株式会社 | リチウムイオン二次電池用負極材料 |
JP6736845B2 (ja) * | 2015-07-22 | 2020-08-05 | 三菱ケミカル株式会社 | 非水系二次電池用炭素材、及び、リチウムイオン二次電池 |
KR20170039976A (ko) * | 2015-10-02 | 2017-04-12 | 주식회사 엘지화학 | 음극 및 이를 포함하는 이차 전지 |
TWI666815B (zh) * | 2018-01-26 | 2019-07-21 | 財團法人工業技術研究院 | 水溶液鋰離子電池及用於其中的電極 |
CN111201659B (zh) * | 2018-02-28 | 2023-08-11 | 松下控股株式会社 | 非水电解质二次电池 |
-
2020
- 2020-07-21 US US17/763,021 patent/US20220344659A1/en active Pending
- 2020-07-21 EP EP20869072.7A patent/EP4037015A4/en active Pending
- 2020-07-21 JP JP2021548377A patent/JPWO2021059705A1/ja active Pending
- 2020-07-21 WO PCT/JP2020/028213 patent/WO2021059705A1/ja active Application Filing
- 2020-07-21 CN CN202080066245.8A patent/CN114424360B/zh active Active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH08287952A (ja) * | 1995-04-11 | 1996-11-01 | Matsushita Electric Ind Co Ltd | 非水電解液二次電池 |
JP2009064574A (ja) * | 2007-09-04 | 2009-03-26 | Nec Tokin Corp | リチウムイオン二次電池 |
JP2012094261A (ja) * | 2010-10-25 | 2012-05-17 | Panasonic Corp | 非水系二次電池用負極板およびこれを用いた非水系二次電池 |
JP2017041407A (ja) | 2015-08-21 | 2017-02-23 | 日産自動車株式会社 | リチウムイオン二次電池 |
JP2018523912A (ja) * | 2015-12-23 | 2018-08-23 | エルジー・ケム・リミテッド | リチウム二次電池用負極活物質及びこれを含むリチウム二次電池用負極 |
WO2019239652A1 (ja) * | 2018-06-15 | 2019-12-19 | 三洋電機株式会社 | 非水電解質二次電池 |
Non-Patent Citations (1)
Title |
---|
See also references of EP4037015A4 |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20220216475A1 (en) * | 2019-04-24 | 2022-07-07 | Sanyo Electric Co., Ltd. | Nonaqueous electrolyte secondary battery |
US20210202932A1 (en) * | 2019-12-26 | 2021-07-01 | Panasonic Corporation | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery |
US20210202933A1 (en) * | 2019-12-26 | 2021-07-01 | Panasonic Corporation | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery |
US11721802B2 (en) * | 2019-12-26 | 2023-08-08 | Panasonic Holdings Corporation | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery |
CN113346043A (zh) * | 2021-06-04 | 2021-09-03 | 江西安驰新能源科技有限公司 | 一种低温锂离子电池正极极片及其制备方法,锂离子电池 |
WO2024106074A1 (ja) * | 2022-11-17 | 2024-05-23 | パナソニックIpマネジメント株式会社 | 非水電解質二次電池 |
Also Published As
Publication number | Publication date |
---|---|
US20220344659A1 (en) | 2022-10-27 |
CN114424360A (zh) | 2022-04-29 |
JPWO2021059705A1 (ja) | 2021-04-01 |
CN114424360B (zh) | 2024-04-12 |
EP4037015A4 (en) | 2023-08-09 |
EP4037015A1 (en) | 2022-08-03 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
WO2021059706A1 (ja) | リチウムイオン二次電池用負極及びリチウムイオン二次電池 | |
WO2021059705A1 (ja) | リチウムイオン二次電池用負極およびリチウムイオン二次電池 | |
WO2019239652A1 (ja) | 非水電解質二次電池 | |
WO2021132114A1 (ja) | 非水電解質二次電池用負極、及び非水電解質二次電池 | |
JP7236658B2 (ja) | 非水電解質二次電池用負極及び非水電解質二次電池 | |
JP7336736B2 (ja) | 非水電解質二次電池 | |
JP7228786B2 (ja) | 非水電解質二次電池用負極および非水電解質二次電池 | |
WO2019239948A1 (ja) | 非水電解質二次電池 | |
CN113272993A (zh) | 非水电解质二次电池用负极和非水电解质二次电池 | |
WO2021106730A1 (ja) | 非水電解質二次電池 | |
CN114080703B (zh) | 二次电池用负极活性物质、以及二次电池 | |
WO2020213499A1 (ja) | 非水電解質二次電池用の負極、及び非水電解質二次電池 | |
US20210202933A1 (en) | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery | |
JP7325050B2 (ja) | 非水電解質二次電池用正極活物質、非水電解質二次電池、及び非水電解質二次電池用正極活物質の製造方法 | |
CN116195091A (zh) | 非水电解质二次电池 | |
EP3683865B1 (en) | Electrode and nonaqueous electrolyte battery | |
WO2023149529A1 (ja) | 非水電解質二次電池 | |
WO2024004836A1 (ja) | 非水電解質二次電池 | |
WO2023181912A1 (ja) | 非水電解質二次電池用正極および非水電解質二次電池 | |
WO2023145603A1 (ja) | 非水電解液二次電池用負極及び非水電解液二次電池 | |
US20220320490A1 (en) | Positive electrode active material for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery | |
WO2024070220A1 (ja) | 非水電解質二次電池 | |
WO2021117615A1 (ja) | 非水電解質二次電池 | |
US11721802B2 (en) | Negative electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery | |
WO2021117748A1 (ja) | 非水電解質二次電池 |
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: 20869072 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2021548377 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2020869072 Country of ref document: EP |
|
ENP | Entry into the national phase |
Ref document number: 2020869072 Country of ref document: EP Effective date: 20220428 |