WO2012077176A1 - リチウムイオン二次電池及びリチウムイオン二次電池の製造方法 - Google Patents
リチウムイオン二次電池及びリチウムイオン二次電池の製造方法 Download PDFInfo
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- WO2012077176A1 WO2012077176A1 PCT/JP2010/071844 JP2010071844W WO2012077176A1 WO 2012077176 A1 WO2012077176 A1 WO 2012077176A1 JP 2010071844 W JP2010071844 W JP 2010071844W WO 2012077176 A1 WO2012077176 A1 WO 2012077176A1
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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
- H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
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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
- H01M4/364—Composites as mixtures
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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
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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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
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
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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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- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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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
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49108—Electric battery cell making
- Y10T29/49115—Electric battery cell making including coating or impregnating
Definitions
- the present invention relates to a lithium ion secondary battery using a negative electrode active material layer including a plurality of types of negative electrode active material particles, and a method of manufacturing such a lithium ion secondary battery.
- a chargeable / dischargeable lithium ion secondary battery (hereinafter also simply referred to as a battery) has been used as a power source for driving portable electronic devices such as hybrid cars, notebook computers, and video camcorders.
- Patent Document 1 uses two types of carbonaceous materials (negative electrode active material particles) of graphite and low-temperature fired carbon as a negative electrode material (negative electrode active material layer) of a negative electrode (negative electrode plate).
- a lithium ion secondary battery was disclosed.
- the present inventors have a battery A (comparative battery C1 described later) using only graphite as the negative electrode active material particles of the negative electrode plate, and a battery B (described later) using only low-temperature fired coke as the negative electrode active material particles of the negative electrode plate.
- the battery characteristics of the comparative battery C2) and the battery C (comparative battery C3 described later) using the negative electrode active material layer in which the low-temperature fired coke which is graphite and amorphous carbon are uniformly mixed were investigated.
- the internal resistance of the battery in the initial stage decreases in the order of battery A, battery C, and battery B.
- the low-temperature fired coke used for the negative electrode active material particles is amorphous and has lower electronic conductivity than graphite. Therefore, the battery A that does not use the low-temperature fired coke for the negative electrode active material particles has the lowest internal resistance among the batteries A to C, and the internal resistance of the battery B that uses only the low-temperature fired coke for the negative electrode active material particles is the highest. Probably higher.
- Lithium deposition is likely to occur when discharged. Therefore, it is considered that the battery B that does not use graphite has the highest capacity maintenance rate among the batteries A to C, and the capacity maintenance rate of the battery A that uses only graphite as the negative electrode active material particles is the lowest.
- the battery C in which graphite and low-temperature fired coke were uniformly mixed as the negative electrode active material particles showed intermediate characteristics between the battery A and the battery B in any of the internal resistance and capacity retention rate. That is, the internal resistance cannot be lowered as much as the battery using only the graphite for the negative electrode active material particles, while the capacity retention after the low-temperature pulse cycle test is as low as the battery using only the low-temperature fired coke for the negative electrode active material particles. Can't be high. That is, in the battery C in which the negative electrode active material layer is uniformly mixed with graphite and low-temperature fired coke, both of the advantages of the battery A (low internal resistance) and the advantages of the battery B (high capacity retention rate) are sufficiently obtained. I can't.
- the present invention has been made in view of such knowledge, and in a battery using graphite and amorphous carbon as negative electrode active material particles, low internal resistance and high capacity maintenance ratio after a low-temperature pulse cycle test are obtained. Provide both batteries. Moreover, it aims at providing the manufacturing method of such a battery.
- One embodiment of the present invention is a negative electrode plate having a negative electrode current collector plate and a negative electrode active material layer including negative electrode active material particles and formed on the negative electrode current collector plate, and a separator on the negative electrode plate.
- a negative electrode active material particle comprising at least first particles made of graphite and second particles made of amorphous carbon, and The negative electrode active material layer is formed on the negative electrode current collector plate side in the layer thickness direction of the negative electrode active material layer as compared to the ratio of the first particles to the whole of the negative electrode active material particles contained in the negative electrode active material layer.
- the ratio of the first particles occupying the whole of the negative electrode active material particles contained in this part is high, compared with the ratio of the second particles occupying the whole of the negative electrode active material particles contained in the negative electrode active material layer.
- the layer thickness of the negative electrode active material layer At the site of direction surface side is the negative electrode active lithium ion secondary battery the ratio of the second particles to the total material particles formed by high contained in this site.
- the battery described above has a low internal resistance and a capacity after a pulse cycle test at a low temperature as compared with a battery in which graphite and amorphous carbon are uniformly mixed in the entire negative electrode active material layer (the battery C described above).
- the maintenance rate can be increased.
- amorphous carbon is easier to exchange lithium ions than graphite, and can suppress the deposition of metallic lithium on its surface during charging and discharging. Therefore, by increasing the ratio of amorphous carbon (second particles) in the negative electrode active material particles at the portion of the negative electrode active material layer that faces the positive electrode plate at the surface, Even during high-rate charging, lithium ions can be easily taken into the negative electrode active material particles (amorphous carbon). Thus, it is considered that lithium deposition on the negative electrode active material layer can be suppressed and a decrease in capacity retention after a low-temperature pulse cycle test can be prevented.
- graphite has higher electronic conductivity than amorphous carbon. For this reason, if the ratio of the graphite (first particles) in the negative electrode active material particles is increased in the portion of the negative electrode active material layer in contact with the negative electrode current collector plate, the first particles (graphite) and the negative electrode current collector plate are increased. It is considered that electrons can be easily exchanged between the two and the internal resistance can be lowered.
- the graphite forming the first particles includes, for example, natural graphite such as flaky graphite, massive graphite, earthy graphite, and artificial graphite. Moreover, the spheroidized graphite which spheroidized natural graphite and artificial graphite is mentioned.
- Examples of the amorphous carbon forming the second particles include low-temperature calcined coke and hard carbon (non-graphitizable carbon).
- the negative electrode active material layer includes a plurality of layers stacked in the layer thickness direction, the first layer located closest to the negative electrode current collector plate, and The negative electrode active material particles in the first layer include the second particles, and the negative electrode active material particles in the second layer include the second particles.
- a lithium ion secondary battery is preferable.
- the negative electrode active material particles in the first layer described above consist of first particles
- the negative electrode active material particles in the second layer consist of second particles.
- the internal resistance of the battery can be made substantially the same as that of the battery using only graphite as the negative electrode active material particles of the negative electrode plate (the above-mentioned battery A), and the capacity retention rate is not as that of the negative electrode active material particles of the negative electrode plate. It can be made substantially the same as a battery using only crystalline carbon (the battery B described above).
- the negative electrode active material layer may be a lithium ion secondary battery including the first layer and the second layer.
- the negative electrode active material layer is composed of the first layer and the second layer, the negative electrode active material layer has a simple layer structure in which no other layer is interposed between the first layer and the second layer. Therefore, the battery can be easily manufactured.
- any one of the lithium ion secondary batteries described above may be used, wherein the density of the first layer is 1.2 to 1.6 g / cm 3 .
- the density of the first layer is 1.2 to 1.6 g / cm 3 . It has been found that a battery has a higher capacity retention rate after a constant current (2C) charge / discharge cycle test at 60 ° C., which will be described later, as compared with a battery in which the density of the first layer is outside the range.
- the capacity retention rate after a constant current charge / discharge cycle test at 60 ° C. is considered to have increased.
- the battery by suppressing the generation of SEI on the negative electrode active material particles, the battery can have a high capacity retention rate after the charge / discharge cycle test described above.
- any one of the above-described lithium ion secondary batteries may be a lithium ion secondary battery in which the density of the second layer is 1.2 g / cm 3 or less.
- a battery in which the density of the second layer is 1.2 g / cm 3 or less. It has been found that the capacity retention rate after a charge pulse cycle test at 0 ° C., which will be described later, is higher than that of a battery in which the density of the second layer is higher than 1.2 g / cm 3 .
- the above-described battery can increase the capacity retention rate after the above-described charge pulse cycle test. Therefore, a battery that can be used for a long period of time can be obtained even when a large current is charged and discharged at a low temperature.
- the vehicle described above is equipped with a battery that achieves both a low internal resistance and a high capacity retention rate after a low-temperature pulse cycle test, and thus can be a vehicle having stable battery performance.
- a negative electrode active material particle comprising at least a first particle made of graphite and a second particle made of amorphous carbon, wherein the negative electrode active material layer comprises: The portion of the negative electrode active material layer on the negative electrode current collector plate side in the portion of the negative electrode active material layer compared to the ratio of the first particles in the negative electrode active material particles contained in the negative electrode active material layer.
- the ratio of the first particles to the whole of the negative electrode active material particles contained in the negative electrode active material particles is high, and the ratio of the second particles to the whole of the negative electrode active material particles contained in the negative electrode active material layer is higher.
- a method of manufacturing a lithium ion secondary battery in which the ratio of the second particles in the whole of the negative electrode active material particles contained in this part is increased, and the active material paste containing the negative electrode active material particles A laminate coating process for forming a multilayer coating film applied multiple times on the negative electrode current collector plate; and a drying process for drying the multilayer coating film, wherein the multilayer coating process includes the active material applied to the upper layer.
- the active material paste applied to the upper layer in the above-described layer coating step has a higher or equal ratio of the second particles in the negative electrode active material particles contained therein, and the ratio of the first particles.
- An active material paste with low or equal is used.
- grain to the whole negative electrode active material particle is high in the site
- a battery including a negative electrode plate in which the ratio of the second particles occupying the entire negative electrode active material particles at the site is increased can be easily and reliably manufactured. Therefore, it is possible to manufacture a battery that reliably achieves both a low internal resistance and a high capacity retention rate after a low-temperature pulse cycle test.
- a negative electrode plate having a negative electrode current collector plate and a negative electrode active material layer formed on the negative electrode current collector plate, the negative electrode plate including negative electrode active material particles;
- a negative electrode active material particle comprising at least a first particle made of graphite and a second particle made of amorphous carbon, wherein the negative electrode active material layer comprises: The portion of the negative electrode active material layer on the negative electrode current collector plate side in the portion of the negative electrode active material layer compared to the ratio of the first particles in the negative electrode active material particles contained in the negative electrode active material layer.
- the ratio of the first particles to the whole of the negative electrode active material particles contained in the negative electrode active material particles is high, and the ratio of the second particles to the whole of the negative electrode active material particles contained in the negative electrode active material layer is higher.
- a method of manufacturing a lithium ion secondary battery in which the ratio of the second particles in the whole of the negative electrode active material particles contained in this part is increased, and the active material paste containing the negative electrode active material particles On the negative electrode current collector plate or on the lower negative electrode active material layer on which the already applied active material paste has been dried, the application step and the drying step on which the applied active material paste is dried are repeated alternately.
- the active material paste to be applied later has a higher or equal ratio of the second particles in the negative electrode active material particles contained in the active material paste, and an active material in which the ratio of the first particles is lower or equal. It is a manufacturing method of the lithium ion secondary battery using a paste.
- the coating step and the drying step described above are alternately repeated, and the coating step of the second particles occupying the whole of the negative electrode active material particles contained in the active material paste applied later.
- An active material paste having a high or equal ratio and a low or equal ratio of the first particles is used.
- grain to the whole negative electrode active material particle is high in the site
- a battery including a negative electrode plate in which the ratio of the second particles occupying the entire negative electrode active material particles at the site is increased can be easily and reliably manufactured. Therefore, it is possible to manufacture a battery that reliably achieves both a low internal resistance and a high capacity retention rate after a low-temperature pulse cycle test.
- FIG. 1 It is a perspective view of the battery concerning Embodiment 1, Embodiment 2, and a modification. It is a perspective view of the negative electrode plate of Embodiment 1 and a modification. It is an expanded sectional view (A section of Drawing 3) of a negative electrode plate of Embodiment 1 and a modification. It is a graph which shows the relationship between the density of the 1st layer and the 2nd capacity maintenance rate of Embodiment 1 and a modification. It is a graph which shows the relationship between the density of the 2nd layer of Embodiment 1, and a modification, and the 3rd capacity maintenance rate. It is explanatory drawing which shows a lamination
- Negative electrode Negative electrode active material layer 21F Surface 21PA First paste 21PB Second paste 22 Negative electrode active material particle 22A First particle 22B Second particle 28 Copper foil (negative electrode current collector plate) 30 Positive electrode plate 40 Separator DT Layer thickness direction L1 First layer (part on the negative electrode current collector plate side) L1B uncompressed first layer (lower negative electrode active material layer) L2 2nd layer (surface side part) PS Laminated coating film Ra first ratio (ratio of first particles in the whole negative electrode active material particles) Rb second ratio (ratio of second particles in the whole negative electrode active material particles)
- the battery 1 includes a lithium ion including an electrode body 10 formed by winding a belt-like positive electrode plate 30, a belt-like negative electrode plate 20, and a belt-like separator 40 interposed between the positive electrode plate 30 and the negative electrode plate 20. It is a secondary battery (see FIG. 1).
- the battery 1 includes an electrode body 10 accommodated in a battery case 80.
- the battery case 80 has a battery case body 81 and a sealing lid 82 both made of aluminum.
- the battery case main body 81 has a bottomed rectangular cylindrical shape, and an insulating film (not shown) made of resin and bent in a box shape is interposed between the battery case 80 and the electrode body 10.
- the sealing lid 82 has a rectangular plate shape, closes the opening of the battery case body 81, and is welded to the battery case body 81.
- the positive electrode terminal portion 91 ⁇ / b> A and the negative electrode terminal portion 92 ⁇ / b> A located on the distal end side penetrate the sealing lid 82, respectively, in FIG. 1.
- An insulating member 95 made of an insulating resin is interposed between the positive terminal portion 91A and the negative terminal portion 92A and the sealing lid 82 to insulate them. Further, a rectangular plate-shaped safety valve 97 is also sealed on the sealing lid 82.
- the electrode body 10 has a wound-type configuration in which the belt-like positive electrode plate 30 and the negative electrode plate 20 are wound into a flat shape via a belt-like separator 40 (see FIG. 1).
- the positive electrode plate 30 and the negative electrode plate 20 face each other with the separator 40 interposed therebetween.
- the positive electrode plate 30 and the negative electrode plate 20 of the electrode body 10 are respectively joined to a plate-like positive electrode current collector 91 or negative electrode current collector 92 bent in a crank shape (see FIG. 1).
- a strip-shaped separator 40 in which polyethylene is sandwiched between two layers of polypropylene is interposed between the positive electrode plate 30 and the negative electrode plate 20 to separate them.
- the separator 40 is entirely impregnated with an electrolytic solution (not shown).
- EC ethylene carbonate
- DMC dimethyl carbonate
- the positive electrode plate 30 includes a strip-shaped aluminum foil (not shown) and two strip-shaped positive electrode active material layers (not shown) disposed on both main surfaces of the aluminum foil.
- the positive electrode active material layer is made of a positive electrode active material particle made of LiNi 1/3 Co 1/3 Mn 1/3 O 2 , a conductive material made of carbon black, and a binder made of polyvinylidene fluoride (PVDF). Including.
- the negative electrode plate 20 extends in a strip shape in the longitudinal direction DA, and is formed of a copper foil 28 made of copper and the strip-shaped 2 formed on both main surfaces 28A and 28A of the copper foil 28. Two negative electrode active material layers 21, 21.
- the negative electrode plate 20 is opposed to the above-described positive electrode plate 30 with the separator 40 described above interposed therebetween.
- the strip-shaped negative electrode active material layer 21 extending in the longitudinal direction DA includes negative electrode active material particles 22 (first particles 22A and second particles 22B described below) and a binder (not shown) made of PVDF.
- the negative electrode active material layer 21 includes two layers (first layer L1 and second layer L2) stacked in the layer thickness direction DT.
- the first layer L1 is a lower layer
- the second layer L2 is an upper layer of the first layer L1, and the surface 21F side.
- the densities of the first layer L1 and the second layer L2 are 1.2 and 1.0 g / cm 3 , respectively.
- the first layer L1 includes first particles 22A made of natural graphite, and the second layer L2 contains second particles 22B made of low-temperature fired coke that is amorphous carbon. . That is, in the first layer L1, the ratio of the first particles 22A to the entire negative electrode active material particles 22 included in the first layer L1 (first ratio Ra) is 100%, and the first layer L1 occupies the entire negative electrode active material particles 22. The ratio of the two particles 22B (second ratio Rb) is 0%. In the second layer L2, the first ratio Ra is 0% and the second ratio Rb is 100%.
- the first particles 22A made of natural graphite have an average particle diameter of 11.2 ⁇ m and a BET specific surface area of 4.6 m 2 / g.
- the second particles 22B made of low-temperature calcined coke have an average particle size of 14.9 ⁇ m and a BET specific surface area of 5.8 m 2 / g.
- the BET specific surface areas of the first particles 22A and the second particles 22B are values measured by the method described in JIS standard K6217-2.
- the abundance ratio of the first particles 22A and the second particles 22B in the entire negative electrode active material layer 21 including the first layer L1 and the second layer L2 is 1: 1. That is, the ratio of the first particles 22A to the entire negative electrode active material particles 22 included in the negative electrode active material layer 21 is 50 wt%. Moreover, the ratio of the 2nd particle
- the first ratio of the first particles 22A in the first layer L1 is higher than the ratio (50 wt%) of the first particles 22A in the entire negative electrode active material layer 21.
- Ra (100%) is increased.
- the second ratio Rb (100%) of the second particles 22B in the second layer L2 is higher than the ratio (50 wt%) of the second particles 22B in the entire negative electrode active material layer 21.
- the inventors conducted the following investigation on the characteristics of the battery 1 according to the first embodiment described above.
- the battery capacity of a new (initial) battery 1 shortly after manufacture was measured. Specifically, first, the battery 1 is charged at a current value of 1/3 C under a temperature environment of 25 ° C. until the voltage of the battery 1 (voltage between terminals) reaches 4.1 V, and then The battery was charged for 2.5 hours while maintaining the voltage (constant current-constant voltage charging). Furthermore, under the same temperature environment of 25 ° C., constant current discharge is performed at a constant current value of 1/3 C until the voltage of the battery 1 reaches 3.0 V, and then the voltage is maintained at 3.0 V. The battery was discharged for 0 hour, and the amount of electricity discharged (charge amount) was measured (hereinafter also referred to as “battery capacity measurement”). The amount of electricity at this time is referred to as “initial battery capacity BC0” of the battery 1.
- the battery 1 was subjected to a test in which a constant current charge of 10 seconds at a current value of 30 C and a constant current discharge of 10 seconds at a current value of 30 C were alternately repeated 250 times in a temperature environment of 0 ° C. (Hereinafter also referred to as “0 ° C. pulse cycle test”).
- the battery capacity at this time is defined as “battery capacity BC1 after first test” of battery 1.
- capacitance maintenance factor) after a 0 degreeC pulse cycle test was computed (Table 1).
- the first capacity maintenance ratio is a value (percentage) obtained by dividing “battery capacity BC1 after first test” by “initial battery capacity BC0” (BC1 / BC0 ⁇ 100 (%)).
- comparative batteries C1, C2, C3, and C4 which are comparative examples of the battery 1, were prepared separately, and the battery characteristics of these batteries were measured in the same manner as the battery 1.
- the comparative battery C1 differs from the battery 1 in that a negative electrode plate having a single-layer negative electrode active material layer containing only the first particles 22A (natural graphite) is used as the negative electrode active material particles.
- Comparative battery C2 differs from battery 1 in that a negative electrode plate having a single-layer negative electrode active material layer containing only second particles 22B (low-temperature fired coke) as negative electrode active material particles was used.
- the comparative battery C3 is different from the battery 1 in that a negative electrode plate having a single negative electrode active material layer in which the first particles 22A and the second particles 22B are uniformly mixed is used.
- the comparative battery C4 includes a layer containing only the second particles 22B on the copper foil side of the negative electrode active material layer on the surface side in the layer thickness direction.
- the negative electrode active material layer in which layers each including only one particle 22A are disposed is different from the battery 1 in that a negative electrode plate is used.
- the value of the impedance of each battery was measured for the battery 1 and the comparative batteries C1, C2, C3, and C4.
- the impedance value of each battery was measured by the AC impedance method (frequency is in the range of 10 ⁇ 1 to 10 5 MHz) using an electrochemical impedance measuring device manufactured by Solartron.
- the impedance value of each battery was determined using the Cole-Cole plot arc obtained by the AC impedance method described above. That is, the distance (absolute value) from the origin of the complex plane where the Cole-Cole plot was performed to the intersection of the Cole-Cole plot and the x-axis (electric resistance) was taken as the impedance value.
- Table 1 shows the impedance values of the batteries (battery 1 and comparative batteries C1, C2, C3, C4).
- the battery 1 (98.2%) is next to the comparative battery C2 (98.4%), and the other batteries (comparative batteries C1, C3, C4). It can be seen that it is sufficiently high. Since natural graphite has anisotropy, the entrance and exit of lithium ions toward the outside is biased compared to isotropic low-temperature calcined coke. For this reason, low-temperature calcined coke is easier to exchange lithium ions than natural graphite, and can suppress the deposition of metallic lithium on its surface when charged with a large current.
- the battery battery 1, comparative battery C2 in which the second particles 22B (low-temperature calcined coke) are present on the surface side in the negative electrode active material layer is larger than the other batteries (comparative batteries C1, C3, C4). It is considered that the precipitation of metallic lithium was suppressed and the decrease in the first capacity retention rate was prevented.
- the battery 1 (76.3 m ⁇ ) is smaller than the comparative battery C1 (76.1 m ⁇ ), and compared with the other batteries (comparative batteries C2, C3, C4). It turns out that it is small enough. Compared to low-temperature calcined coke that is amorphous, natural graphite has higher electronic conductivity.
- the battery battery 1, comparative battery C1 in which the first particle 22A (natural graphite) is abundant in the negative electrode active material particles in the portion of the negative electrode active material layer located on the copper foil side (in contact with the copper foil)
- the battery battery 1, comparative battery C1 in which the first particle 22A (natural graphite) is abundant in the negative electrode active material particles in the portion of the negative electrode active material layer located on the copper foil side (in contact with the copper foil)
- it is considered that electrons can be easily transferred between the negative electrode active material layer and the copper foil 28, and the impedance value is reduced.
- the comparative battery C2 using only the second particles 22B (low-temperature calcined coke) as the negative electrode active material particles of the negative electrode active material layer can have a higher first capacity retention ratio, but the impedance value is larger than that of other batteries.
- the comparative battery C1 using only the first particles 22A (natural graphite) as the negative electrode active material particles of the negative electrode active material layer can have a smaller impedance value, but the first capacity retention rate is lower than that of other batteries.
- the comparative battery C3 using a negative electrode plate having a single negative electrode active material layer in which the first particles 22A and the second particles 22B are uniformly mixed as the negative electrode active material particles has a first capacity retention ratio and an impedance.
- both values were intermediate values between the comparative battery C1 and the comparative battery C2, and halfway characteristics were obtained. Furthermore, the negative electrode plate which has the negative electrode active material layer which has arrange
- the battery 1 according to the first embodiment has a high first capacity retention rate substantially equal to that of the comparative battery C2, and a small impedance value substantially equivalent to that of the comparative battery C1.
- the battery 1 is compared with a battery (comparative battery C3) in which graphite (first particles 22A) and amorphous carbon (second particles 22B) are uniformly mixed in the entire negative electrode active material layer. Impedance is low, and capacity retention after a low-temperature pulse cycle test can be increased.
- an impedance can be made low by including many 1st particles in the part which touches copper foil among negative electrode active material layers.
- the first capacity retention rate can be increased by including a large amount of the second particles in the portion of the negative electrode active material layer exposed on the surface.
- the first particles 22 are used as the negative electrode active material particles 22 in the first layer L1 of the negative electrode active material layer 21, and the second particles 22B are used as the negative electrode active material particles 22 in the second layer L2. .
- the impedance of the battery 1 can be set to a value that is substantially the same as that of the battery using only the first particles 22A as the negative electrode active material particles of the negative electrode plate (comparative battery C1). It can be set to the same good value as the battery (comparative battery C2) using only the second particles 22B as the negative electrode active material particles of the plate.
- the negative electrode active material layer 21 is composed of two layers of the first layer L1 and the second layer L2, the negative electrode active material layer 21 can have a simple layer structure, The battery 1 can be easily manufactured.
- the present inventors conducted the following investigation on the relationship between the density of the first layer used in the battery 1 and the battery characteristics. That is, first, similarly to the battery 1 described above, a plurality of 15 types of batteries using a negative electrode plate in which a negative electrode active material layer was composed of a first layer and a second layer were prepared. In these batteries, the density of the first layer is set to any one of five levels of 1.1, 1.2, 1.4, 1.6, and 1.7 g / cm 3 , and the density of the second layer is set. , 1.0, 1.1, 1.3 g / cm 3 . Note that the combination of the first layer and the second layer of each battery does not overlap with other batteries.
- the battery capacity was measured for each of these batteries.
- the battery capacity at this time is defined as “initial battery capacity BC0” of each battery.
- initial battery capacity BC0 the battery capacity of each battery.
- constant current charging and constant current discharging are alternately performed 1000 times at a current value of 2C so that the charging state (SOC) of each battery becomes SOC 0% and SOC 100%.
- the test was repeated (hereinafter also referred to as “60 ° C. cycle test”). Thereafter, the battery capacity measurement described above was performed again for each battery, and the battery capacity of each battery after the 60 ° C. cycle test was measured.
- the battery capacity at this time is defined as “battery capacity after second test BC2” of each battery.
- This second capacity maintenance ratio is a value (percentage) obtained by dividing “second battery capacity BC2 after test” by “initial battery capacity BC0” (BC2 / BC0 ⁇ 100 (%)).
- FIG. 4 shows a graph showing the relationship between the density of the first layer in each battery and the second capacity retention ratio (capacity retention ratio after the 60 ° C. cycle test) of each battery.
- the result of the battery having the density of the second layer of 1.0 g / cm 3 is a circle ( ⁇ )
- the result of the battery of 1.1 g / cm 3 is a square ( ⁇ )
- 1.1 g / cm 3 The results of the batteries are plotted with triangles ( ⁇ ).
- the second capacity retention rate of the battery using the first layer having a density of 1.2, 1.4 and 1.6 g / cm 3 is The second capacity retention rate of the battery using the first layer having the density of 1.2 and 1.7 g / cm 3 is considerably lower than 87%, while it is about 87%.
- the density of the first layer is 1.2 to 1.6 g / cm 3
- the first layer is appropriately pressed, there is no deterioration in electronic conductivity due to expansion and contraction, and the density Since it is difficult for the negative electrode active material layer (first layer) to crack due to being too high, it is considered that the decrease in the capacity retention rate (second capacity retention rate) after the 60 ° C. cycle test was suppressed.
- the density is by using the first layer L1 is 1.2 g / cm 3 in the range of 1.2 ⁇ 1.6g / cm 3. Therefore, even in this battery 1, by suppressing the generation of SEI on the negative electrode active material particles 22, the battery 1 has a high second capacity retention rate after the above-described 60 ° C. cycle test.
- the present inventors conducted the following investigation on the relationship between the density of the second layer used in the battery 1 and the battery characteristics. That is, first, the same batteries as those used in the 60 ° C. cycle test described above were prepared.
- Each battery was subjected to a test in which a constant current charge of 10 seconds at a current value of 30 C and a constant current discharge of 10 seconds at a current value of 30 C were alternately repeated 280 times in a temperature environment of 0 ° C. ( Hereinafter, also referred to as “0 ° C. charge pulse cycle test”). Then, the battery capacity measurement mentioned above was performed about each battery, and the battery capacity of each battery after a 0 degreeC charge pulse cycle test was measured. In addition, let the battery capacity at this time be "battery capacity BC3 after 3rd test" of each battery.
- This third capacity retention rate is a value (percentage) obtained by dividing “battery capacity BC3 after the third test” of each battery by “initial battery capacity BC0” of each battery measured before the 60 ° C. cycle test described above. Yes (BC3 / BC0 ⁇ 100 (%)).
- FIG. 5 shows a graph showing the relationship between the density of the second layer in each battery and the third capacity retention ratio (capacity retention ratio after the 0 ° C. charge pulse cycle test) of each battery.
- the third capacity retention ratio capacity retention ratio after the 0 ° C. charge pulse cycle test
- the result of the battery is plotted with a triangle ( ⁇ ), the result of the battery of 1.6 g / cm 3 is marked with ⁇ , and the result of the battery of 1.7 g / cm 3 is plotted with *.
- the third capacity retention rate of the battery using the second layer whose density is 1.0 and 1.2 g / cm 3 is 97% or more.
- the third capacity retention rate of the battery using the second layer having a density of 1.3 g / cm 3 is significantly low from 97%.
- the density is by using a second layer L2 is 1.2 g / cm 3 or less of 1.0 g / cm 3.
- capacitance maintenance factor after the above-mentioned 0 degreeC charge pulse cycle test can also be made high. Therefore, the battery 1 that can be used for a long time can be obtained even when charging and discharging a large current at a low temperature.
- the coating apparatus 100 includes an unwinding unit 101, a first coater 110, a second coater 120, a heater 130, a winding unit 102, and a plurality of auxiliary rollers 140 and 140 (see FIG. 6).
- the first coater 110 includes a metal paste holding portion 111 that stores therein a first paste 21PA, which will be described later, and the first paste 21PA held in the paste holding portion 111 on the main surface of the copper foil 28. And a discharge port 112 that discharges continuously toward 28A.
- the discharge port 112 is slit-shaped, on the main surface 28A of the copper foil 28 moving in the longitudinal direction DA, in order to discharge the first paste 21PA in a strip shape in the width direction of the copper foil 28 (in FIG. 6, It opens parallel to the depth direction.
- the second coater 120 has a metal paste holding part 121 and a discharge port 122, similar to the first coater 110.
- the paste holding part 121 stores the 2nd paste 21PB mentioned later inside.
- the discharge port 122 is slit-shaped, and the width direction of the copper foil 28 (see FIG. 5) is used to discharge the second paste 21PB in a strip shape on the first coating film PSA formed on the main surface 28A of the copper foil 28. 6 in the depth direction).
- the heater 130 heats and dries the first paste 21PA (first coating PSA) and the second paste 21PB (second coating PSB) applied to the copper foil 28.
- the copper foil 28 is warmed while moving between the two heaters 130, 130, and the first paste 21 PA (first coating film PSA) and the second paste applied to the copper foil 28 are laminated and applied.
- the paste 21PB (second coating film PSB) is gradually dried.
- the first paste 21PA (first coating film PSA) and the second paste 21PB (second coating film PSB) are completely dried, that is, the first paste 21PA (first coating film PSA).
- the solvent in the second paste 21PB (second coating film PSB) are all evaporated.
- a second paste 21PB made by kneading the second particles 22B made of low-temperature fired coke, CMC, and SBR together with a solvent is prepared in advance.
- the ratio of the first particles 22A to the entire negative electrode active material particles included in the first paste 21PA is 100%
- the ratio of the second particles 22B is 0%
- the first ratio Ra is 0%
- the second ratio Rb is 100%. Accordingly, the second paste 21PB has a higher second ratio Rb and a lower first ratio Ra than the first paste 21PA.
- the above-mentioned first paste 21PA is put into the paste holding unit 111 of the first coater 110, and the second paste 21PB is put into the paste holding unit 121 of the second coater 120, respectively. Then, the strip-shaped copper foil 28 wound around the unwinding portion 101 is moved in the longitudinal direction DA, and the first paste 21PA is applied onto the main surface 28A of the copper foil 28 by the first coater 110. As a result, a first coating film PSA made of the first paste 21PA is formed on the main surface 28A of the copper foil 28.
- a second paste 21PB is applied on the first coating film PSA by the second coater 120.
- the second coating film PSB made of the second paste 21PB is formed on the first coating film PSA.
- a laminated coating PS in which the first coating PSA and the second coating PSB are laminated is formed on the main surface 28A of the copper foil 28 (see FIG. 7).
- a drying process is performed using the heater 130 of the coating apparatus 100. That is, the laminated coating PS was dried with the heater 130 to obtain an uncompressed active material layer 21B before pressing. After this drying step, the single-side supported copper foil 28K carrying the uncompressed active material layer 21B on the main surface 28A on one side is once wound around the winding unit 102.
- the first paste 21PA and the second paste 21PB are also applied to the other main surface 28A of the above-described single-side supported copper foil 28K (copper foil 28), and the multilayer coating film is applied. PS is formed.
- the laminated coating PS is also completely dried by the heater 130.
- an active material laminate 20B before pressing in which the uncompressed active material layers 21B and 21B are laminated on both the main surfaces 28A and 28A of the copper foil 28 is produced.
- the active material laminated plate 30B before pressing is pressed by using a pressing device (not shown), and the negative electrode plate 20 formed by laminating two compressed negative electrode active material layers 21 and 21 on both sides of the copper foil 28. (See FIG. 2).
- a positive electrode plate 30 was produced. Specifically, positive electrode active material particles, a conductive material and a binder (not shown) were mixed with a solvent to produce a positive electrode paste (not shown). And the above-mentioned positive electrode paste was apply
- the electrode body 20 is formed by winding the separator 40 between the positive electrode plate 30 and the negative electrode plate 20 manufactured as described above. Further, the positive electrode current collecting member 91 and the negative electrode current collecting member 92 are welded to the positive electrode plate 30 and the negative electrode plate 20, respectively. Thereafter, the electrode body 20 is accommodated in the battery case main body 81, and the battery case main body 81 is sealed by welding with the sealing lid 82. Thereafter, an electrolytic solution is injected from a liquid injection hole (not shown), and the liquid injection hole is sealed to complete the battery 1 (see FIG. 1).
- the active material paste applied to the upper layer of the first paste 21PA in the above-described layer coating step is the second occupying the negative electrode active material particles 22 included in itself.
- a second paste 21PB in which the ratio of the particles 22B (second ratio Rb) is higher than that of the first paste 21PA and the ratio of the first particles 22A (first ratio Ra) is lower than that of the first paste 21PA is used.
- the ratio of the first particles 22A to the entire negative electrode active material particles 22 is high in the portion (first layer L1) on the layer thickness direction DT copper foil 28 side of the negative electrode active material layer 21, and the negative electrode active material
- the first ratio Ra in the first layer L1 was set to 100%.
- the second ratio Rb in the second layer L2 was set to 100%.
- the first ratio Ra in the first layer L1 and the second ratio Rb in the second layer L2 do not have to be 100%, and the first particles occupying the entire negative electrode active material particles included in the negative electrode active material layer.
- the first ratio Ra of the first layer L1 is set higher than the ratio, and the ratio of the second particles occupying the whole negative electrode active material particles contained in the negative electrode active material layer is higher than that of the second layer L2. It is preferable to increase the second ratio Rb.
- the first ratio Ra of the first layer L1 is a value higher than 50% (for example, 85 %).
- the second ratio Rb of the second layer L2 is a value higher than 50% (for example, 80%). It is also good.
- the battery 1 using the negative electrode plate 20 having the negative electrode active material layer 21 including the first layer L1 and the second layer L2 is shown.
- a plurality of three or more layers are provided. It may be composed of layers.
- the active material paste applied to the upper layer in the layer application step has a higher or equal ratio of the second particles to the negative electrode active material particles contained in itself, and the ratio of the first particles is
- a laminated coating film may be formed using an active material paste that is low or equal.
- Embodiment 1 the laminated coating process which forms a laminated coating film by apply
- an active material paste any one of the first paste and the second paste described above
- a coating process and a drying process described later are alternately performed using the coating apparatus 200 illustrated in FIG. That is, after the first application step of applying the first paste 21PA, a first drying step of drying the applied first paste 21PA is performed. Further, after the second application step of applying the second paste 21PB, a second drying step of drying the applied second paste 21PB is performed.
- the coating apparatus 200 used for the above-mentioned first coating process, first drying process, second coating process, and second drying process will be described.
- the coating apparatus 200 is similar to the first embodiment described above in that the unwinding unit 101, the first coater 110, the second coater 120, the second heater 230B, the winding unit 102, and a plurality of auxiliary rollers 140, 140 are provided. (Refer to FIG. 8).
- the coating apparatus 200 also includes a first heater 230A between the first coater 110 and the second coater 120 (see FIG. 8).
- the first heater 230A heats and dries the first paste 21PA (first coating film PSA) applied to the copper foil 28 by the first coater 110.
- first paste 21PA first coating film PSA
- the first heater 230A heats and dries the first paste 21PA (first coating film PSA) applied to the copper foil 28 by the first coater 110.
- the copper foil 28 is warmed and the first paste 21PA (first coating film PSA) applied to the copper foil 28 is dried. Gradually progresses. And when passing through the first heater 230A, the first paste 21PA (first coating film PSA) is completely dried.
- the second heater 230B heats the second paste 21PB (second coating PSB) applied on the completely dried first paste 21PA (first coating PSA). And dry.
- the first coating step is performed using such a coating apparatus 200.
- a first paste 21PA and a second paste 21PB similar to those of the first embodiment are prepared in advance. Therefore, in the second paste 21PB, the ratio of the second particles 22B to the entire anode active material particles 22 included in the second paste 21PB is higher than that of the first paste 21PA, and the ratio of the first particles 22A is the first paste 21PA. Lower than.
- the first paste 21PA is put into the paste holding unit 111 of the first coater 110, the second paste 21PB is put into the paste holding unit 121 of the second coater 120, and the strip-shaped copper foil 28 wound around the unwinding unit 101 is wound. Is moved in the longitudinal direction DA, and the first paste 21PA is applied to the main surface 28A of the copper foil 28 by the first coater 110. Thereby, the first coating film PSA made of the first paste 21PA is formed on the main surface 28A of the copper foil 28 (see FIG. 8).
- a first drying step is performed using the first heater 230A of the coating apparatus 200. That is, the first coating film PSA was dried by the first heater 230A to form an uncompressed first layer L1B (see FIG. 8).
- the copper foil 28 on which the uncompressed first layer L1B is formed is moved in the longitudinal direction DA, and the second paste 21PB is applied onto the uncompressed first layer L1B by the second coater 120 (second application step). ). That is, in the second application step, the second paste 21PB is applied onto the uncompressed first layer L1B, which is the lower negative electrode active material layer that is formed by drying the first paste 21PA that has already been applied to the copper foil 28. Thereby, the 2nd coating film PSB which consists of 2nd paste 21PB is formed in the upper layer of uncompressed 1st layer L1B (refer FIG. 8).
- a second drying process is performed using the second heater 230B of the coating apparatus 200. That is, the second coating PSB was dried by the second heater 230B to form an uncompressed second layer L2B, thereby forming an uncompressed active material layer 21B (see FIGS. 8 and 9). Thereafter, the single-side supported copper foil 28 ⁇ / b> K carrying the uncompressed active material layer 21 ⁇ / b> B on the main surface 28 ⁇ / b> A on one side is temporarily wound around the winding unit 102.
- the coating apparatus 200 is used again, and the coating process and the drying process are repeated on the other main surface 28A of the above-described single-side supported copper foil 28K (copper foil 28).
- the active material laminate 30B before pressing is pressed, and two compressed negative electrode active material layers 21 and 21 are laminated on both sides of the copper foil 28.
- a negative electrode plate 20 is obtained (see FIG. 2).
- the battery 101 is completed in the same manner as in the first embodiment (see FIG. 1).
- the coating process and the drying process were alternately performed in the order of the first coating process, the first drying process, the second coating process, and the second drying process.
- the second paste 21PB having a second ratio Rb and a lower first ratio Ra than the first paste 21PA applied in the first application step is used.
- the ratio of the first particles 22A to the entire negative electrode active material particles 22 is high in the portion (first layer L1) on the layer thickness direction DT copper foil 28 side of the negative electrode active material layer 21, and the negative electrode active material
- the battery 101 including the negative electrode plate 20 in which the ratio of the second particles 22B to the entire negative electrode active material particles 22 is increased in the layer 21 in the layer thickness direction DT surface 21F side (second layer L2) of the layer 21 is easily and It can be manufactured reliably. Therefore, it is possible to manufacture a battery 101 that reliably achieves both a low internal resistance and a high capacity retention rate after a low-temperature pulse cycle test.
- the first ratio Ra in the first layer L1 was set to 100% as in the first embodiment.
- the second ratio Rb in the second layer L2 was set to 100%.
- the first ratio Ra in the first layer L1 and the second ratio Rb in the second layer L2 do not have to be 100%, and the first particles occupying the entire negative electrode active material particles included in the negative electrode active material layer.
- the first ratio Ra of the first layer L1 is set higher than the ratio, and the ratio of the second particles occupying the whole negative electrode active material particles contained in the negative electrode active material layer is higher than that of the second layer L2. It is preferable to increase the second ratio Rb.
- the first ratio Ra of the first layer L1 is a value higher than 50% (for example, 70 %).
- the second ratio Rb of the second layer L2 is a value higher than 50% (for example, 75%). It is also good.
- the battery 101 using the negative electrode plate 20 having the negative electrode active material layer 21 composed of the first layer L1 and the second layer L2 is shown, but for example, a plurality of layers of three or more layers You may comprise.
- the active material paste to be applied later has a higher or equal ratio of the second particles to the negative electrode active material particles contained therein, and a lower ratio of the first particles.
- the active material paste is preferably applied on the negative electrode current collector plate or the lower negative electrode active material layer using the same active material paste.
- the first paste 21PA and the second paste 21PB are completely dried, respectively, but in the midway drying (first drying process), the active material paste is half-dried. It may be dry.
- a vehicle 300 according to the second embodiment includes a battery pack 310 including a plurality of the above-described batteries 1 (or batteries 101).
- vehicle 300 is a hybrid vehicle that is driven by using engine 340, front motor 320, and rear motor 330 in combination.
- the vehicle 300 includes a vehicle body 390, an engine 340, a front motor 320, a rear motor 330, a cable 350, an inverter 360, and a battery pack 310 having a rectangular box shape.
- the battery pack 310 accommodates a plurality of the batteries 1 (or batteries 101) described above.
- the vehicle 300 according to the second embodiment is equipped with the battery 1 (or the battery 101) that achieves both a low internal resistance and a high capacity retention rate after a low-temperature pulse cycle test, and thus has stable battery performance. It can be set as the vehicle 300 which has.
- the present invention has been described according to the first and second embodiments and the modified embodiments.
- the present invention is not limited to the above-described embodiments, and can be appropriately modified and applied without departing from the gist thereof. Needless to say.
- scaly graphite is used for the first particles 22A.
- natural graphite other than the scaly graphite (block graphite, earth graphite, etc.) or artificial graphite is used for the first particles. May be.
- the low-temperature firing coke is used for the second particles 22B, for example, hard carbon (non-graphitizable carbon) may be used for the second particles.
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Abstract
Description
20 負極板
21 負極活物質層
21F 表面
21PA 第1ペースト
21PB 第2ペースト
22 負極活物質粒子
22A 第1粒子
22B 第2粒子
28 銅箔(負極集電板)
30 正極板
40 セパレータ
DT 層厚方向
L1 第1層(負極集電板側の部位)
L1B 未圧縮第1層(下層負極活物質層)
L2 第2層(表面側の部位)
PS 積層塗膜
Ra 第1比率(負極活物質粒子全体に占める第1粒子の比率)
Rb 第2比率(負極活物質粒子全体に占める第2粒子の比率)
次に、本発明の実施形態1について、図面を参照しつつ説明する。まず、本実施形態1にかかる電池1について、図1を参照して説明する。この電池1は、帯状の正極板30と、帯状の負極板20と、正極板30と負極板20との間に介在させた帯状のセパレータ40とを捲回してなる電極体10を備えるリチウムイオン二次電池である(図1参照)。この電池1は、電極体10を電池ケース80に収容してなる。
次に、本発明にかかる電池の製造方法の変形形態について、図面を参照しつつ説明する。実施形態1では、第1塗膜上に第2塗膜を塗布して積層塗膜を形成する積層塗布工程と、その積層塗膜全体を一度に乾燥させる乾燥工程とを行った。これに対し、本変形形態にかかる電池101の製造方法では、活物質ペースト(前述の第1ペースト及び第2ペーストのいずれか)を塗布する塗布工程と、この塗膜工程で塗布した活物質ペーストを乾燥させる乾燥工程とを交互に繰り返す点で、上述した実施形態1とは異なる。そこで、実施形態1と異なる点を中心に説明し、実施形態1と同様の部分の説明は省略または簡略化する。なお、実施形態1と同様の部分については同様の作用効果を生じる。また、同内容のものには同番号を付して説明する。
本実施形態2にかかる車両300は、前述した電池1(又は電池101)を複数含むバッテリパック310を搭載したものである。具体的には、図10に示すように、車両300は、エンジン340、フロントモータ320及びリアモータ330を併用して駆動するハイブリッド自動車である。この車両300は、車体390、エンジン340、これに取り付けられたフロントモータ320、リアモータ330、ケーブル350、インバータ360、及び、矩形箱形状のバッテリパック310を有している。このうちバッテリパック310は、前述した電池1(又は電池101)を複数収容してなる。
Claims (7)
- 負極集電板、及び、負極活物質粒子を含み、上記負極集電板上に形成されてなる負極活物質層、を有する負極板と、
上記負極板に、セパレータを介して対向する正極板と、を備える
リチウムイオン二次電池であって、
上記負極活物質粒子は、
少なくとも、黒鉛からなる第1粒子、及び、非晶質炭素からなる第2粒子からなり、
上記負極活物質層は、
この負極活物質層に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率に比して、上記負極活物質層のうち層厚方向上記負極集電板側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率が高く、
上記負極活物質層に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率に比して、上記負極活物質層のうち上記層厚方向表面側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率が高くされてなる
リチウムイオン二次電池。 - 請求項1に記載のリチウムイオン二次電池であって、
前記負極活物質層は、
前記層厚方向に積層された複数の層からなり、
最も前記負極集電板側に位置する第1層、及び、最も前記表面側に位置する第2層を含み、
上記第1層の前記負極活物質粒子は、前記第1粒子からなり、
上記第2層の上記負極活物質粒子は、前記第2粒子からなる
リチウムイオン二次電池。 - 請求項2に記載のリチウムイオン二次電池であって、
前記負極活物質層は、
前記第1層及び前記第2層からなる
リチウムイオン二次電池。 - 請求項2又は請求項3に記載のリチウムイオン二次電池であって、
前記第1層の密度が1.2~1.6g/cm3である
リチウムイオン二次電池。 - 請求項2~請求項4のいずれか一項に記載のリチウムイオン二次電池であって、
前記第2層の密度が1.2g/cm3以下である
リチウムイオン二次電池。 - 負極集電板、及び、負極活物質粒子を含み、上記負極集電板上に形成されてなる負極活物質層、を有する負極板と、
上記負極板に、セパレータを介して対向する正極板と、を備え、
上記負極活物質粒子は、
少なくとも、黒鉛からなる第1粒子、及び、非晶質炭素からなる第2粒子からなり、
上記負極活物質層は、
この負極活物質層に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率に比して、上記負極活物質層のうち層厚方向上記負極集電板側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率が高く、
上記負極活物質層に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率に比して、上記負極活物質層のうち上記層厚方向表面側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率が高くされてなる
リチウムイオン二次電池の製造方法であって、
上記負極活物質粒子を含む活物質ペーストを、上記負極集電板上に複数回重ねて塗布した積層塗膜を形成する積層塗布工程と、
上記積層塗膜を乾燥させる乾燥工程と、を備え、
上記積層塗布工程は、
上層に塗布する上記活物質ペーストほど、自身に含む上記負極活物質粒子全体に占める上記第2粒子の比率が高いか等しく、かつ、上記第1粒子の比率が低いか等しい活物質ペーストを用いる
リチウムイオン二次電池の製造方法。 - 負極集電板、及び、負極活物質粒子を含み、上記負極集電板上に形成されてなる負極活物質層、を有する負極板と、
上記負極板に、セパレータを介して対向する正極板と、を備え、
上記負極活物質粒子は、
少なくとも、黒鉛からなる第1粒子、及び、非晶質炭素からなる第2粒子からなり、
上記負極活物質層は、
この負極活物質層に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率に比して、上記負極活物質層のうち層厚方向上記負極集電板側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第1粒子の比率が高く、
上記負極活物質層に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率に比して、上記負極活物質層のうち上記層厚方向表面側の部位において、この部位に含まれる上記負極活物質粒子全体に占める上記第2粒子の比率が高くされてなる
リチウムイオン二次電池の製造方法であって、
上記負極活物質粒子を含む活物質ペーストを、上記負極集電板上、又は、既に塗布した活物質ペーストを乾燥させた下層負極活物質層上に塗布する塗布工程と、
塗布された上記活物質ペーストを乾燥させる乾燥工程と、を交互に繰り返し、
上記塗布工程は、
後に塗布する上記活物質ペーストほど、自身に含む上記負極活物質粒子全体に占める上記第2粒子の比率が高いか等しく、かつ、上記第1粒子の比率が低いか等しい活物質ペーストを用いる
リチウムイオン二次電池の製造方法。
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