WO2010150377A1 - Lithium ion secondary battery, and vehicle - Google Patents

Lithium ion secondary battery, and vehicle Download PDF

Info

Publication number
WO2010150377A1
WO2010150377A1 PCT/JP2009/061586 JP2009061586W WO2010150377A1 WO 2010150377 A1 WO2010150377 A1 WO 2010150377A1 JP 2009061586 W JP2009061586 W JP 2009061586W WO 2010150377 A1 WO2010150377 A1 WO 2010150377A1
Authority
WO
WIPO (PCT)
Prior art keywords
power generation
lithium ion
ion secondary
secondary battery
aqueous electrolyte
Prior art date
Application number
PCT/JP2009/061586
Other languages
French (fr)
Japanese (ja)
Inventor
英輝 萩原
Original Assignee
トヨタ自動車株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by トヨタ自動車株式会社 filed Critical トヨタ自動車株式会社
Priority to PCT/JP2009/061586 priority Critical patent/WO2010150377A1/en
Publication of WO2010150377A1 publication Critical patent/WO2010150377A1/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present invention relates to a lithium ion secondary battery and a vehicle equipped with the lithium ion secondary battery.
  • Lithium ion secondary batteries are attracting attention as power sources for portable devices and as driving power sources for vehicles such as electric vehicles and hybrid vehicles.
  • a lithium ion secondary battery an electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound into a flat shape, the active material coating part of the positive electrode plate, the active material coating part of the negative electrode plate, and the separator
  • a lithium ion secondary battery has been proposed that includes an electrode body having a power generation unit that overlaps with a nonaqueous electrolyte solution that is a non-aqueous electrolyte solution containing Li salt and is included in the power generation unit (for example, (See Patent Documents 1 to 3).
  • the power generation unit includes an upper end side power generation arc-shaped portion that forms the upper end portion of the power generation unit, and a lower end side power generation arc-shaped portion that forms the lower end portion of the power generation unit.
  • the power generation flat portion is located between the upper end side power generation arc-shaped portion and the lower end side power generation arc-shaped portion.
  • the power generation flat portion refers to a portion of the power generation portion in which the positive electrode plate, the negative electrode plate, and the separator are stacked in the thickness direction of the electrode body.
  • the upper end side power generation arc-shaped portion is positioned on the upper end side in the vertical direction of the power generation unit when the lithium ion secondary battery is used (the upper end portion in the vertical direction is formed), and the positive electrode plate, the negative electrode plate, and the separator have an arc shape.
  • the lower end side power generation arc-shaped portion is located on the lower end side in the vertical direction of the power generation unit when the lithium ion secondary battery is used (the lower end portion in the vertical direction is formed), and the positive electrode plate, the negative electrode plate, and the separator have an arc shape. The part that overlaps.
  • the Li ion concentration (Li salt concentration) of the nonaqueous electrolytic solution may be biased in the power generation unit with the use (charge / discharge). .
  • the Li ion concentration of the non-aqueous electrolyte contained in both ends of the power generation flat portion increases, while power generation flatness
  • the Li ion concentration of the non-aqueous electrolyte contained in the central part of the part is lowered, and the Li ion concentration of the non-aqueous electrolyte is biased at the power generation flat part.
  • the Li ion concentration of the non-aqueous electrolyte contained in both ends of the power generation flat portion decreases, while the central portion of the power generation flat portion
  • the Li ion concentration of the non-aqueous electrolyte contained in the battery rises, and the Li ion concentration of the non-aqueous electrolyte is biased at the power generation flat portion.
  • the Li ion concentration of the nonaqueous electrolytic solution is biased in the power generation flat portion.
  • the internal resistance of the lithium ion secondary battery is increased.
  • the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is greatly reduced in a part of the power generation flat portion, the internal resistance of the lithium ion secondary battery is greatly increased. For this reason, the output of the lithium ion secondary battery may be greatly reduced.
  • the present invention has been made in view of such a situation, and an object thereof is to provide a lithium ion secondary battery and a vehicle that can suppress an increase in internal resistance of the battery.
  • One aspect of the present invention is an electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound into a flat shape, and the active material coating portion of the positive electrode plate, the active material coating portion of the negative electrode plate, and the separator
  • a lithium ion secondary battery comprising: an electrode body having a power generation unit that overlaps with a non-aqueous electrolyte containing a Li salt, and the non-aqueous electrolyte included in the power generation unit
  • the power generation unit includes: The upper end side power generation arc-shaped portion that forms the upper end portion of the power generation unit, the lower end side power generation arc shape portion that forms the lower end of the power generation unit, and the power generation located between the upper end side power generation arc shape portion and the lower end side power generation arc shape portion
  • the concentration of the Li salt in the non-aqueous electrolyte contained in the upper power generation arc-shaped portion is the flatness of the non-aqueous electrolyte contained in the power generation
  • the Li salt concentration (Li ion concentration) of the non-aqueous electrolyte contained in the upper end side power generation arc-shaped portion is set to the power generation flat portion and the lower end side power generation arc shape portion (that is, the upper end side). It was made higher than the Li salt concentration of the non-aqueous electrolyte contained in the other part of the power generation unit excluding the side power generation arc-shaped part). Thereby, even when Li ion (Li salt) in the non-aqueous electrolyte decreases in a part of the power generation flat portion by repeatedly performing high-rate charging or discharging, it flows down from the upper end side power generation arc-shaped portion. Li ions can be supplied to a site where Li ions are reduced by a non-aqueous electrolyte having a high Li ion concentration (Li salt concentration).
  • the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is possible to prevent the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte from greatly decreasing in a part of the power generation flat portion. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion (concentration difference between the portion where the Li ion concentration is high and the portion where it is low) can be reduced. Therefore, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
  • the power generation flat part is a part of the power generation part in which the active material coating part of the positive electrode plate, the active material coating part of the negative electrode plate, and the separator are laminated in the thickness direction of the electrode body.
  • the upper end side power generation arc-shaped part is located on the upper end side in the vertical direction of the power generation part when the lithium ion secondary battery is used (the upper end part in the vertical direction is formed), and the active material coating part and the negative electrode plate of the positive electrode plate
  • the active material coating portion and the separator overlap each other in an arc shape.
  • the lower end side power generation arc-shaped part is located on the lower end side in the vertical direction of the power generation part when using the lithium ion secondary battery (the lower end part in the vertical direction is formed), and the active material coating part and the negative electrode plate of the positive electrode plate The active material coating portion and the separator overlap each other in an arc shape.
  • the concentration of the Li salt in the non-aqueous electrolyte contained in the upper end side power generation arc-shaped portion is included in the power generation flat portion and the lower end side power generation arc shape portion.
  • a lithium ion secondary battery that is made 0.2 mol / L or more higher than the concentration of the Li salt in the non-aqueous electrolyte is preferable.
  • the concentration of the Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is changed to the power generation flat portion and the lower-end side power generation. It is necessary to make it higher than a certain level than the concentration of Li salt in the non-aqueous electrolyte contained in the arcuate portion.
  • the concentration of Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is set to the Li salt of the non-aqueous electrolyte contained in the power-generation flat portion and the lower-end power generation arc-shaped portion. It is higher than the salt concentration by 0.2 mol / L or more.
  • the Li ion concentration (Li salt concentration) of the nonaqueous electrolytic solution is possible to prevent the Li ion concentration (Li salt concentration) of the nonaqueous electrolytic solution from greatly decreasing in a part of the power generation flat portion. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion (concentration difference between the portion where the Li ion concentration is high and the portion where it is low) can be reduced. Therefore, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
  • any one of the above lithium ion secondary batteries may be a lithium ion secondary battery that is charged or discharged at 10 C or higher.
  • the Li salt concentration (Li ion concentration) of the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is set to the power generation flat portion and the lower-end power generation arc-shaped portion (that is, The Li salt concentration of the non-aqueous electrolyte contained in the other part of the power generation unit excluding the upper end side power generation arc-shaped part) is set higher. For this reason, even when charging or discharging is performed at a high rate of 10 C or higher, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
  • 1C is a current value that allows constant current discharge of a battery with 100% SOC to SOC 0% in one hour. Therefore, 10 C corresponds to a current value that can discharge a battery with 100% SOC to SOC 0% in 6 minutes.
  • SOC is an abbreviation for State (Of Charge (charging state, charging rate).
  • another aspect of the present invention is a vehicle in which any one of the above lithium ion secondary batteries is mounted as a driving power source for the vehicle.
  • the vehicle described above is equipped with one of the lithium ion secondary batteries as a power source for driving the vehicle.
  • the lithium ion secondary battery is a lithium ion secondary battery that can suppress an increase in internal resistance of the battery. For this reason, in the above-described vehicle, an increase in the internal resistance of the lithium ion secondary battery, which is a driving power source, can be suppressed, so that a decrease in the output of the driving power source (lithium ion secondary battery) can be suppressed. . Therefore, in the above-described vehicle, it is possible to suppress a decrease in traveling performance.
  • a lithium ion secondary battery mounted as a driving power source for an electric vehicle or a hybrid vehicle is often charged or discharged at a high rate, so that the internal resistance tends to increase.
  • an increase in the internal resistance of the lithium ion secondary battery that is a driving power source can be suppressed, so that a decrease in the output of the driving power source can also be suppressed for electric vehicles and hybrid vehicles. .
  • the fall of driving performance can be suppressed.
  • FIG. 1 is a schematic view of a vehicle (hybrid vehicle) according to an embodiment. It is a longitudinal cross-sectional view of the lithium ion secondary battery concerning embodiment. It is a perspective view of the electrode body of the lithium ion secondary battery concerning embodiment. It is a longitudinal cross-sectional view of the electric power generation part of the same electrode body. It is the elements on larger scale of the electric power generation part, and is equivalent to the B section enlarged view of FIG. It is a figure which shows the fluctuation
  • the vehicle 1 includes a vehicle body 2, an engine 3, a front motor 4, a rear motor 5, an assembled battery 10, and a cable 7, and the engine 3, the front motor 4, the rear motor 5, and the like. It is a hybrid car that is driven in combination. Specifically, the vehicle 1 is configured to be able to travel using the engine 3, the front motor 4, and the rear motor 5 by known means using the assembled battery 10 as a driving power source for the front motor 4 and the rear motor 5. ing.
  • the assembled battery 10 is attached to the vehicle body 2 of the vehicle 1 and is connected to the front motor 4 and the rear motor 5 by a cable 7.
  • This assembled battery 10 has a plurality (for example, 100) of lithium ion secondary batteries 100 electrically connected in series. Charging / discharging of the lithium ion secondary battery 100 constituting the assembled battery 10 is controlled by a control device (not shown).
  • the lithium ion secondary battery 100 is discharged at 10 C or higher when sudden acceleration or the like is performed.
  • the lithium ion secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode external terminal 121, and a negative electrode external terminal 131.
  • the battery case 110 is a hard case having a metal rectangular housing part 111 and a metal lid part 112 forming a rectangular parallelepiped housing space.
  • An electrode body 150 and the like are housed inside the battery case 110 (the square housing portion 111).
  • FIG. 2 is a vertical cross-sectional view of the lithium ion secondary battery 100 in a posture during use. Therefore, as will be described later, the lithium ion secondary battery 100 uses the power generation unit 160 of the electrode body 150 with the upper end side power generation arc-shaped portion 161 on the upper side in the vertical direction and the lower end side power generation arc-shaped portion 163 on the lower side in the vertical direction. (Charging / discharging is performed).
  • the electrode body 150 is an oblong cross section, and is a flat wound body in which a sheet-like positive electrode plate 155, a negative electrode plate 156, and a separator 157 are wound into a flat shape (see FIGS. 3 and 4).
  • the positive electrode plate 155 has a positive electrode current collecting member 151 made of an aluminum foil and a positive electrode mixture 152 (a mixture containing the positive electrode active material 153) applied on the surface thereof (see FIG. 5).
  • the negative electrode plate 156 has a negative electrode current collecting member 158 made of copper foil and a negative electrode mixture 159 (a mixture containing the negative electrode active material 154) coated on the surface thereof (see FIG. 5).
  • the electrode body 150 includes a power generation unit 160, a positive electrode winding unit 150d, and a negative electrode winding unit 150c.
  • the positive electrode winding part 150d is adjacent to one side (right side in FIG. 2) of the power generation part 160 in the axial direction X (left and right direction in FIG. 2) of the electrode body 150, and the surface of the positive electrode current collecting member 151 in the positive electrode plate 155. This is a portion where only the positive electrode active material uncoated portion 155b where the positive electrode mixture 152 is not coated overlaps.
  • the negative electrode winding part 150c is adjacent to the other side (left side in FIG. 2) of the power generation part 160 in the axial direction X (left and right direction in FIG. 2) of the electrode body 150, and the surface of the negative electrode current collecting member 158 in the negative electrode plate 156 This is a portion where only the negative electrode active material uncoated portion 156b where the negative electrode mixture 159 is not coated overlaps.
  • the positive electrode winding unit 150d is electrically connected to the positive electrode external terminal 121 through the positive electrode current collector 122 (see FIG. 2).
  • the negative electrode winding unit 150 c is electrically connected to the negative electrode external terminal 131 through the negative electrode current collector 132.
  • the positive electrode external terminal 121 and the positive electrode current collector 122 are integrally formed to constitute the positive electrode current collector terminal member 120. Further, the negative electrode external terminal 131 and the negative electrode current collector 132 are integrally formed to constitute the negative electrode current collector terminal member 130.
  • the power generation unit 160 includes a positive electrode active material coating unit 155c in which the positive electrode mixture 152 is coated on the surface of the positive electrode current collecting member 151 in the positive electrode plate 155 and a negative electrode current collecting member 158 in the negative electrode plate 156. This is a portion where the negative electrode active material coating part 156c coated with the negative electrode mixture 159 and the separator 157 overlap (see FIGS. 4 and 5).
  • the power generation unit 160 includes an upper end power generation arc-shaped portion 161 that forms the upper end of the power generation unit 160, a lower end side power generation arc-shaped portion 163 that forms the lower end of the power generation unit 160, and an upper end side power generation arc-shaped portion 161 and a lower end side power generation arc-shaped portion. And a power generation flat part 162 located between the two parts (see FIGS. 2 to 4).
  • the positive electrode active material coating portion 155c, the negative electrode active material coating portion 156c, and the separator 157 in the power generation portion 160 form a planar shape, and the thickness direction of the electrode body 150 (the left-right direction in FIG. 4). It is the part laminated
  • the upper end side power generation arc-shaped portion 161 is located on the upper end side in the vertical direction (Y direction, vertical direction in FIGS. 2 and 4) of the power generation unit 160 when the lithium ion secondary battery 100 is used (see FIG. 2).
  • the positive electrode active material coating part 155c, the negative electrode active material coating part 156c, and the separator 157 overlap each other in an arc shape.
  • the lower end side power generation arc-shaped part 163 is located on the lower end side in the vertical direction (Y direction, vertical direction in FIGS. 2 and 4) of the power generation unit 160 when the lithium ion secondary battery 100 is used (see FIG. 2).
  • the positive electrode active material coating part 155c, the negative electrode active material coating part 156c, and the separator 157 overlap each other in an arc shape.
  • lithium nickelate is used as the positive electrode active material 153.
  • natural graphite is used as the negative electrode active material 154.
  • a polypropylene / polyethylene / polypropylene three-layer structure composite porous sheet is used as the separator 157.
  • the non-aqueous electrolyte containing Li salt is contained in the power generation unit 160.
  • the power generation unit 160 contains two types of non-aqueous electrolytes (first non-aqueous electrolyte 140B and second non-aqueous electrolyte 140C) having different Li salt concentrations.
  • first non-aqueous electrolyte 140B is included in the upper end side power generation arc-shaped portion 161
  • the second non-aqueous electrolyte 140C is included in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163 (FIG. 2). FIG. 4).
  • the concentration of the Li salt in the first nonaqueous electrolyte solution 140B is set higher than the concentration of the Li salt in the second nonaqueous electrolyte solution 140C.
  • the concentration of the Li salt in the first nonaqueous electrolytic solution 140B is 1.2 mol / L
  • the concentration of the Li salt in the second nonaqueous electrolytic solution 140C is 1.0 mol / L.
  • the concentration of the Li salt in the nonaqueous electrolyte solution 140B included in the upper end side power generation arc-shaped portion 161 is set to be equal to that of the nonaqueous electrolyte solution 140C included in the power generation flat portion 162 and the lower end side power generation arc shape portion 163. It is higher than the concentration of Li salt.
  • a lithium ion secondary battery mounted as a driving power source for a hybrid vehicle is often charged or discharged at a high rate (for example, 10 C or more).
  • a high rate for example, 10 C or more.
  • Li ions (Li salts) in the non-aqueous electrolyte decrease in part of the power generation flat portion.
  • the Li ion concentration of the non-aqueous electrolyte is biased in the power generation flat portion, and the internal resistance of the lithium ion secondary battery is increased.
  • Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is greatly reduced in a part of the power generation flat portion, the internal resistance of the lithium ion secondary battery is greatly increased (see the comparison form in FIG. 6).
  • the lithium ion secondary battery including the positive electrode plate, the negative electrode plate, and the electrode body obtained by winding the separator in a flat shape is repeatedly subjected to high-rate charging or discharging, and the upper end side power generation arc shape It was found that a part of the non-aqueous electrolyte contained in the part flows down to the power generation flat part. This phenomenon is considered to occur as follows. By repeatedly performing high-rate charging or discharging on the lithium ion secondary battery, the upper end side power generation arc-shaped portion repeatedly expands and contracts.
  • the concentration of the Li salt of the non-aqueous electrolyte 140B included in the upper end side power generation arc-shaped portion 161 is changed to the power generation flat portion 162 and the lower end side power generation.
  • the concentration is higher than the concentration of Li salt in the non-aqueous electrolyte solution 140C contained in the arc-shaped portion 163.
  • Li-ion (Li salt) in the non-aqueous electrolyte 140C decreases in a part of the power generation flat portion 162 by repeatedly performing high-rate charging or discharging, the upper-end-side power generation arc-shaped portion 161 Li ion can be efficiently supplied to the site where the Li ions are decreased by the non-aqueous electrolyte solution 140B having a high Li ion concentration (Li salt concentration) that has flowed down.
  • the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is greatly decreasing in a part of the power generation flat portion 162. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion 162 (concentration difference between the portion where the Li ion concentration is high and the portion where the Li ion concentration is low) can be reduced. For this reason, the raise of the internal resistance of the lithium ion secondary battery 100 can be suppressed (refer embodiment of FIG. 6). Thereby, about the vehicle 1 which is a hybrid vehicle, since the output fall of the drive power supply (assembled battery 10 which connected the some lithium ion secondary battery 100 in series) can be suppressed, the fall of driving performance is suppressed. Can do.
  • non-aqueous electrolytes 140B and 140C six fluorides, which are Li salts, are mixed in a non-aqueous solvent in which EC (ethylene carbonate), DMC (dimethyl carbonate), and EMC (ethyl methyl carbonate) are mixed.
  • EC ethylene carbonate
  • DMC dimethyl carbonate
  • EMC ethyl methyl carbonate
  • a nonaqueous electrolytic solution in which lithium phosphate (LiPF 6 ) is dissolved is used.
  • the concentration of Li salt (LiPF 6 ) is set to 1.2 mol / L.
  • the concentration of Li salt (LiPF 6 ) is 1.0 mol / L.
  • 1C is a current value that allows constant current discharge of a battery with 100% SOC to SOC 0% in one hour. Therefore, 20 C corresponds to a current value that can discharge a battery with 100% SOC to SOC 0% in 3 minutes.
  • SOC is an abbreviation for State (Of Charge (charging state, charging rate).
  • the lithium ion secondary battery of the comparative form from which only a nonaqueous electrolyte solution differs was prepared.
  • the comparative lithium ion secondary battery only the second non-aqueous electrolyte 140C is used as the non-aqueous electrolyte. Therefore, in the lithium ion secondary battery of the comparative form, not only the power generation flat portion and the lower end side power generation arc-shaped portion but also the upper end side power generation arc-shaped portion contains the non-aqueous electrolyte 140C.
  • the entire power generation unit contains the non-aqueous electrolyte solution 140C having a concentration of Li salt (LiPF 6 ) of 1.0 mol / L.
  • LiPF 6 Li salt
  • the lithium ion secondary battery of this comparative form was also charged and discharged for 7000 cycles in the same manner as the lithium ion secondary battery 100 of the embodiment.
  • each internal resistance value is expressed as a relative value, where the initial value of the internal resistance of the lithium ion secondary battery 100 of the embodiment (IV resistance value before cycle charge / discharge) is 1.
  • the IV resistance value was calculated as follows. First, the battery voltage (terminal voltage VA) is measured for each lithium ion secondary battery. Thereafter, each lithium ion secondary battery is discharged at a constant current of 1 C for 10 seconds, and the battery voltage after discharge (terminal voltage VB) is measured. The voltage difference between terminals before and after constant current discharge (VA-VB) was divided by the discharge current value to obtain an IV resistance value.
  • the lithium ion secondary battery 100 of the embodiment and the lithium ion secondary battery of the comparative embodiment had the same internal resistance initial value (IV resistance value before performing cycle charge / discharge). .
  • the internal resistance of the lithium ion secondary battery of the comparative example was larger than the internal resistance of the lithium ion secondary battery 100 of the exemplary embodiment.
  • the internal resistance greatly increased after the start of cycle charge / discharge.
  • the internal resistance reached the maximum and increased to 4.7 times the initial value.
  • the internal resistance increased after the start of cycle charge / discharge, but the rate of increase was considerably smaller than that of the comparative lithium ion secondary battery. became.
  • the internal resistance reached the maximum, which was 2.6 times the initial value.
  • the lithium ion secondary battery 100 of the embodiment was about 1 ⁇ 2 of the internal resistance of the lithium ion secondary battery of the comparative form. From this result, it can be said that in the lithium ion secondary battery 100 of the embodiment, an increase in the internal resistance was greatly suppressed as compared with the lithium ion secondary battery of the comparative form.
  • the internal resistance of the lithium ion secondary battery 100 of the embodiment and the lithium ion secondary battery of the comparative example both decreased, and became substantially constant after 5000 cycles. Specifically, in the lithium ion secondary battery of the comparative form, the internal resistance showed a value about 2.1 times the initial value after 5000 cycles. On the other hand, in the lithium ion secondary battery 100 of the embodiment, the internal resistance showed a value 1.5 times the initial value after 5000 cycles.
  • the lithium ion secondary battery 100 of the embodiment Comparing the internal resistance after 5000 cycles, the lithium ion secondary battery 100 of the embodiment was about 2/3 of the internal resistance of the comparative lithium ion secondary battery. Also from this result, it can be said that the lithium ion secondary battery 100 of the embodiment was able to suppress an increase in internal resistance as compared with the lithium ion secondary battery of the comparative form. From the above results, it can be said that the lithium ion secondary battery 100 of the embodiment is a lithium ion secondary battery that can suppress an increase in internal resistance.
  • the reason why the increase in internal resistance can be suppressed in the lithium ion secondary battery 100 of the embodiment is considered as follows.
  • the high-rate discharge (20C discharge) is repeatedly performed in the cycle charge / discharge test described above, when the electrode body 150 is viewed in the axial direction (X direction) (see FIG. 2), both ends in the axial direction of the power generation flat portion 162 A part of the Li ions of the non-aqueous electrolyte 140C included in the parts 162c and 162d moves to the axially central part 162b of the power generation flat part 162.
  • Li ion (Li salt) of the non-aqueous electrolyte 140C contained in the axial direction both ends 162c and 162d of the power generation flat portion 162 decreases.
  • the Li ion (Li salt) of the nonaqueous electrolyte 140C contained in the axial end portions 162c and 162d of the power generation flat portion 162 is reduced. The amount of reduction increases.
  • the concentration of the Li salt of the first non-aqueous electrolyte 140B included in the upper end side power generation arc-shaped portion 161 is set to the power generation flat portion 162 and the lower end side power generation arc shape.
  • the concentration of Li salt in the second non-aqueous electrolyte solution 140 ⁇ / b> C included in the portion 163 is set higher.
  • the concentration of the Li salt in the first non-aqueous electrolyte solution 140B included in the upper end side power generation arc-shaped portion 161 is set to the second non-aqueous electrolyte solution included in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163. It is 0.2 mol / L or more higher than the concentration of the 140C Li salt.
  • the non-aqueous electrolyte solution 140B having a high concentration (Li salt concentration) can efficiently supply Li ions to both axial ends 162c and 162d (sites where Li ions decrease) of the power generation flat portion 162.
  • the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte from greatly decreasing at both axial ends 162c and 162d of the power generation flat portion 162. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion 162 (concentration difference between the portion where the Li ion concentration is high and the portion where the Li ion concentration is low) can be reduced. Thereby, it is considered that an increase in internal resistance of the lithium ion secondary battery 100 can be suppressed.
  • the Li salt concentration of the non-aqueous electrolyte in the upper-end power generation arc-shaped portion is equal to the Li salt concentration of the non-aqueous electrolyte in the power generation flat portion.
  • the amount of Li ions supplied to the power generation flat portion by the non-aqueous electrolyte flowing down from the upper end side power generation arc portion is considerably reduced. Therefore, as shown in FIG. 6, it is considered that the internal resistance of the comparative lithium ion secondary battery is considerably larger than that of the lithium ion secondary battery 100 of the embodiment.
  • a method for manufacturing the lithium ion secondary battery 100 will be described.
  • a positive electrode plate 155 in which a positive electrode mixture 152 is coated on the surface of a strip-shaped positive electrode current collecting member 151 is prepared.
  • a negative electrode plate 156 in which a negative electrode mixture 159 is coated on the surface of a strip-shaped negative electrode current collecting member 158 is prepared.
  • a negative electrode plate 156, a separator 157, a positive electrode plate 155, and a separator 157 are laminated in this order.
  • the positive electrode active material uncoated portion 155b of the positive electrode plate 155 and the negative electrode active material uncoated portion 156b of the negative electrode plate 156 are oriented so that they face each other in the width direction (left-right direction in FIG. 9).
  • Stacking is performed so that the active material uncoated portion 155 b does not overlap the separator 157 and the negative electrode plate 156, and the negative electrode active material uncoated portion 156 b does not overlap the separator 157 and the positive electrode plate 155.
  • the laminated negative electrode plate 156, separator 157, positive electrode plate 155, and separator 157 are wound into a flat shape to form the electrode body 150 (see FIG. 3).
  • the positive electrode winding part 150 d of the electrode body 150 and the positive electrode current collector part 122 of the positive electrode current collector terminal member 120 are welded.
  • the negative electrode winding portion 150 c of the electrode body 150 and the negative electrode current collector portion 132 of the negative electrode current collector terminal member 130 are welded.
  • the electrode body 150 to which the positive current collecting terminal member 120 and the negative current collecting terminal member 130 are welded is accommodated in the rectangular accommodating portion 111 and the opening of the rectangular accommodating portion 111 is closed by the lid portion 112.
  • the lid portion 112 and the square housing portion 111 are welded.
  • the electrode housing body 101 in which the electrode body 150 is housed in the battery case 110 is completed (see FIG. 10).
  • a through hole 112 b that penetrates the lid 112 is formed at the center of the lid 112.
  • a through-hole 111b that penetrates the bottom 111c is formed at the center of the bottom 111c of the rectangular accommodating portion 111.
  • a non-aqueous electrolyte is injected into the battery case 110 (specifically, inside the power generation unit 160 of the electrode body 150).
  • the electrode container 101 is turned upside down (the power generation portion 160 of the electrode body 150 has the upper end side power generation arc-shaped portion 161 on the lower side in the vertical direction.
  • the nonaqueous electrolyte solution 140B is injected into the battery case 110 through the through hole 112b of the lid portion 112.
  • the injection amount of the non-aqueous electrolyte 140B is set to an amount in which the non-aqueous electrolyte 140B is contained in the entire upper end side power generation arc-shaped portion 161.
  • the concentration of Li salt in the nonaqueous electrolyte 140B (LiPF 6) is adjusted to 1.2 mol / L.
  • the through hole 112 b of the lid portion 112 is temporarily sealed with a sealing member 114.
  • the gas G in the battery case 110 is discharged to the outside through the through hole 111b formed in the bottom 111c of the rectangular accommodating part 111, and the inside of the battery case 110 is depressurized ( (See FIG. 12).
  • the set pressure of the vacuum pump (not shown) is 90 kPa, and the pressure in the battery case 110 is reduced by the vacuum pump for 5 seconds.
  • the non-aqueous electrolyte solution 140 ⁇ / b> B can be contained in the upper end side power generation arc-shaped portion 161.
  • the vertical direction of the electrode housing 101 is returned to the original state (for the power generation unit 160 of the electrode body 150, the upper end side power generation arc-shaped portion 161 is vertically upward and the lower end side power generation arc shape is The part 163 is set to the lower side in the vertical direction).
  • the nonaqueous electrolytic solution 140C is injected into the battery case 110 through the through hole 111b of the rectangular accommodating portion 111.
  • the injection amount of the non-aqueous electrolyte 140C is an amount in which the non-aqueous electrolyte 140C is contained in the entire power generation flat portion 162 and the lower end side power generation arc-shaped portion 163.
  • the concentration of the non-aqueous electrolyte Li salt 140C (LiPF 6) is adjusted to 1.0 mol / L.
  • the through hole 111 b of the rectangular accommodating portion 111 is sealed with a sealing member 113.
  • the temporary sealing of the through hole 112b of the lid 112 is released (the sealing member 114 is removed), and the gas in the battery case 110 is passed through the through hole 112b of the lid 112 using a vacuum pump (not shown).
  • G is discharged to the outside, and the inside of the battery case 110 is depressurized (see FIG. 16).
  • the set pressure of the vacuum pump (not shown) is set to 90 kPa, and the pressure in the battery case 110 is reduced by the vacuum pump for 25 seconds.
  • the non-aqueous electrolyte solution 140 ⁇ / b> B can be contained in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163. Thereafter, the through hole 112 b of the lid portion 112 is sealed with the sealing member 114. Thereby, the lithium ion secondary battery 100 (refer FIG. 2) of this embodiment is completed.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)

Abstract

Provided is a lithium ion secondary battery (100) comprising an electrode member (150) having a positive plate (155), a negative plate (156), and a separator (157) wound thereon in a flat shape.  The electrode member (150) includes a generating portion (160), in which a positive electrode activating substance applied portion (155c) of the positive plate (155), a negative electrode activating substance applied portion (156c) of the negative plate (156), and the separator (157) overlap.  The generating portion (160) includes an upper end generating arcuate portion (161) forming the upper end portion of the generating portion (160), a lower end generating arcuate portion (163) forming the lower end portion of the generating portion (160), and a generating flat portion (162) positioned between the upper end generating arcuate portion (161) and the lower end generating arcuate portion (163).  A first nonaqueous electrolyte (140B) contained in the upper end generating arcuate portion (161) has a larger Li salt concentration than a second nonaqueous electrolyte (140C) contained in the generating flat portion (162) and the lower end generating arcuate portion (163).

Description

リチウムイオン二次電池、及び、車両Lithium ion secondary battery and vehicle
　本発明は、リチウムイオン二次電池、及び、このリチウムイオン二次電池を搭載した車両に関する。 The present invention relates to a lithium ion secondary battery and a vehicle equipped with the lithium ion secondary battery.
　リチウムイオン二次電池は、携帯機器の電源として、また、電気自動車やハイブリッド自動車などの車両の駆動用電源として注目されている。近年、リチウムイオン二次電池として、正極板、負極板、及びセパレータを扁平形状に捲回した電極体であって、正極板の活物質塗工部と負極板の活物質塗工部とセパレータとが重なり合う発電部を有する電極体と、Ｌｉ塩を含有する非水電解液であって発電部の内部に含まれる非水電解液と、を備えるリチウムイオン二次電池が提案されている（例えば、特許文献１～３参照）。 Lithium ion secondary batteries are attracting attention as power sources for portable devices and as driving power sources for vehicles such as electric vehicles and hybrid vehicles. In recent years, as a lithium ion secondary battery, an electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound into a flat shape, the active material coating part of the positive electrode plate, the active material coating part of the negative electrode plate, and the separator A lithium ion secondary battery has been proposed that includes an electrode body having a power generation unit that overlaps with a nonaqueous electrolyte solution that is a non-aqueous electrolyte solution containing Li salt and is included in the power generation unit (for example, (See Patent Documents 1 to 3).
特開２００７－５３０５５号公報JP 2007-53055 A 特開２００７－３０５３２２号公報JP 2007-305322 A 特開２００８－１６２５０号公報JP 2008-16250 A
　特許文献１～３に記載されているリチウムイオン二次電池では、発電部が、当該発電部の上端部をなす上端側発電弧状部と、当該発電部の下端部をなす下端側発電弧状部と、上端側発電弧状部と下端側発電弧状部との間に位置する発電平坦部とからなっている。ここで、発電平坦部とは、発電部のうち、正極板と負極板とセパレータとが平面状をなして電極体の厚み方向に積層された部位をいう。また、上端側発電弧状部とは、リチウムイオン二次電池の使用時において、発電部の鉛直方向上端側に位置し（鉛直方向上端部をなし）、正極板と負極板とセパレータとが弧状をなして重なる部位をいう。また、下端側発電弧状部とは、リチウムイオン二次電池の使用時において、発電部の鉛直方向下端側に位置し（鉛直方向下端部をなし）、正極板と負極板とセパレータとが弧状をなして重なる部位をいう。 In the lithium ion secondary batteries described in Patent Documents 1 to 3, the power generation unit includes an upper end side power generation arc-shaped portion that forms the upper end portion of the power generation unit, and a lower end side power generation arc-shaped portion that forms the lower end portion of the power generation unit. The power generation flat portion is located between the upper end side power generation arc-shaped portion and the lower end side power generation arc-shaped portion. Here, the power generation flat portion refers to a portion of the power generation portion in which the positive electrode plate, the negative electrode plate, and the separator are stacked in the thickness direction of the electrode body. In addition, the upper end side power generation arc-shaped portion is positioned on the upper end side in the vertical direction of the power generation unit when the lithium ion secondary battery is used (the upper end portion in the vertical direction is formed), and the positive electrode plate, the negative electrode plate, and the separator have an arc shape. The part that overlaps. The lower end side power generation arc-shaped portion is located on the lower end side in the vertical direction of the power generation unit when the lithium ion secondary battery is used (the lower end portion in the vertical direction is formed), and the positive electrode plate, the negative electrode plate, and the separator have an arc shape. The part that overlaps.
　ところで、特許文献１～３のリチウムイオン二次電池では、その使用（充放電）に伴って、発電部において、非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）に偏りが生じることがあった。具体的には、例えば、ハイレートの充電を繰り返すと、電極体をその軸線方向について見たとき、発電平坦部の両端部に含まれる非水電解液のＬｉイオン濃度が上昇し、一方、発電平坦部の中央部に含まれる非水電解液のＬｉイオン濃度が低下し、発電平坦部において非水電解液のＬｉイオン濃度に偏りが生じてしまう。反対に、ハイレートの放電を繰り返すと、電極体をその軸線方向について見たとき、発電平坦部の両端部に含まれる非水電解液のＬｉイオン濃度が低下し、一方、発電平坦部の中央部に含まれる非水電解液のＬｉイオン濃度が上昇し、発電平坦部において非水電解液のＬｉイオン濃度に偏りが生じてしまう。このように、リチウムイオン二次電池についてハイレートの充電または放電を繰り返し行うと、発電平坦部において、非水電解液のＬｉイオン濃度に偏りが生じてしまう。 By the way, in the lithium ion secondary batteries of Patent Documents 1 to 3, the Li ion concentration (Li salt concentration) of the nonaqueous electrolytic solution may be biased in the power generation unit with the use (charge / discharge). . Specifically, for example, when high-rate charging is repeated, when the electrode body is viewed in the axial direction, the Li ion concentration of the non-aqueous electrolyte contained in both ends of the power generation flat portion increases, while power generation flatness The Li ion concentration of the non-aqueous electrolyte contained in the central part of the part is lowered, and the Li ion concentration of the non-aqueous electrolyte is biased at the power generation flat part. On the other hand, when high-rate discharge is repeated, when the electrode body is viewed in the axial direction, the Li ion concentration of the non-aqueous electrolyte contained in both ends of the power generation flat portion decreases, while the central portion of the power generation flat portion The Li ion concentration of the non-aqueous electrolyte contained in the battery rises, and the Li ion concentration of the non-aqueous electrolyte is biased at the power generation flat portion. As described above, when the high-rate charging or discharging is repeatedly performed on the lithium ion secondary battery, the Li ion concentration of the nonaqueous electrolytic solution is biased in the power generation flat portion.
　上述のように、発電平坦部において非水電解液のＬｉイオン濃度に偏りが生じると、リチウムイオン二次電池の内部抵抗が上昇してしまう。特に、発電平坦部の一部において非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下すると、リチウムイオン二次電池の内部抵抗が大きく上昇してしまう。このために、リチウムイオン二次電池の出力が大きく低下してしまうことがあった。 As described above, when the Li ion concentration of the non-aqueous electrolyte is uneven in the power generation flat part, the internal resistance of the lithium ion secondary battery is increased. In particular, when the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is greatly reduced in a part of the power generation flat portion, the internal resistance of the lithium ion secondary battery is greatly increased. For this reason, the output of the lithium ion secondary battery may be greatly reduced.
　本発明は、かかる現状に鑑みてなされたものであって、電池の内部抵抗の上昇を抑制することができるリチウムイオン二次電池、及び車両を提供することを目的とする。 The present invention has been made in view of such a situation, and an object thereof is to provide a lithium ion secondary battery and a vehicle that can suppress an increase in internal resistance of the battery.
　本発明の一態様は、正極板、負極板、及びセパレータを扁平形状に捲回した電極体であって、上記正極板の活物質塗工部と上記負極板の活物質塗工部と上記セパレータとが重なり合う発電部を有する電極体と、Ｌｉ塩を含有する非水電解液であって、上記発電部に含まれる非水電解液と、を備えるリチウムイオン二次電池において、上記発電部は、当該発電部の上端部をなす上端側発電弧状部と、当該発電部の下端部をなす下端側発電弧状部と、上記上端側発電弧状部と上記下端側発電弧状部との間に位置する発電平坦部と、からなり、上記上端側発電弧状部に含まれる上記非水電解液の上記Ｌｉ塩の濃度は、上記発電平坦部及び上記下端側発電弧状部に含まれる上記非水電解液の上記Ｌｉ塩の濃度よりも高くされてなるリチウムイオン二次電池である。 One aspect of the present invention is an electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound into a flat shape, and the active material coating portion of the positive electrode plate, the active material coating portion of the negative electrode plate, and the separator In a lithium ion secondary battery comprising: an electrode body having a power generation unit that overlaps with a non-aqueous electrolyte containing a Li salt, and the non-aqueous electrolyte included in the power generation unit, the power generation unit includes: The upper end side power generation arc-shaped portion that forms the upper end portion of the power generation unit, the lower end side power generation arc shape portion that forms the lower end of the power generation unit, and the power generation located between the upper end side power generation arc shape portion and the lower end side power generation arc shape portion And the concentration of the Li salt in the non-aqueous electrolyte contained in the upper power generation arc-shaped portion is the flatness of the non-aqueous electrolyte contained in the power generation flat portion and the lower power generation arc-shaped portion. Lithium ion bismuth higher than the concentration of Li salt It is a battery.
　本願発明者の研究調査により、正極板、負極板、及びセパレータを扁平形状に捲回した電極体を備えるリチウムイオン二次電池について、ハイレートの充電または放電を繰り返し行うと、上端側発電弧状部に含まれている非水電解液の一部が、発電平坦部に流れ落ちることが判明した。この現象は、次のようにして起こると考えられる。リチウムイオン二次電池についてハイレートの充電または放電を繰り返し行うことで、上端側発電弧状部が膨張と収縮を繰り返す。これ（膨張と収縮によるポンプ効果）により、上端側発電弧状部に含まれている非水電解液の一部が上端側発電弧状部から押し出され、重力によって、上端側発電弧状部の下方に位置する発電平坦部に流れ落ちると考えられる。 According to the research conducted by the inventor of the present application, when a high-rate charge or discharge is repeated for a lithium ion secondary battery including an electrode body in which a positive electrode plate, a negative electrode plate, and a separator are wound in a flat shape, It was found that a part of the non-aqueous electrolyte contained flows down to the power generation flat part. This phenomenon is considered to occur as follows. By repeatedly charging or discharging the lithium ion secondary battery at a high rate, the upper end side power generation arc-shaped portion repeatedly expands and contracts. Due to this (pump effect due to expansion and contraction), a part of the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is pushed out of the upper-end-side power generation arc-shaped portion, and is positioned below the upper-end-side power generation arc-shaped portion by gravity. It is thought that it flows down to the power generation flat part.
　そこで、上述のように、リチウムイオン二次電池について、上端側発電弧状部に含まれる非水電解液のＬｉ塩濃度（Ｌｉイオン濃度）を、発電平坦部及び下端側発電弧状部（すなわち、上端側発電弧状部を除いた発電部の他の部位）に含まれる非水電解液のＬｉ塩濃度よりも高くした。これにより、ハイレートの充電または放電を繰り返し行うことで、発電平坦部の一部において非水電解液中のＬｉイオン（Ｌｉ塩）が減少してゆく場合でも、上端側発電弧状部から流れ落ちてきたＬｉイオン濃度（Ｌｉ塩濃度）の高い非水電解液によって、Ｌｉイオンが減少してゆく部位にＬｉイオンを供給することができる。 Therefore, as described above, for the lithium ion secondary battery, the Li salt concentration (Li ion concentration) of the non-aqueous electrolyte contained in the upper end side power generation arc-shaped portion is set to the power generation flat portion and the lower end side power generation arc shape portion (that is, the upper end side). It was made higher than the Li salt concentration of the non-aqueous electrolyte contained in the other part of the power generation unit excluding the side power generation arc-shaped part). Thereby, even when Li ion (Li salt) in the non-aqueous electrolyte decreases in a part of the power generation flat portion by repeatedly performing high-rate charging or discharging, it flows down from the upper end side power generation arc-shaped portion. Li ions can be supplied to a site where Li ions are reduced by a non-aqueous electrolyte having a high Li ion concentration (Li salt concentration).
　これにより、発電平坦部の一部において非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下することを防止できる。さらには、発電平坦部における非水電解液のＬｉイオン濃度の偏りの程度（Ｌｉイオン濃度が高い部位と低い部位との濃度差）を小さくすることができる。従って、リチウムイオン二次電池の内部抵抗の上昇を抑制することができる。 Thereby, it is possible to prevent the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte from greatly decreasing in a part of the power generation flat portion. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion (concentration difference between the portion where the Li ion concentration is high and the portion where it is low) can be reduced. Therefore, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
　なお、発電平坦部とは、発電部のうち、正極板の活物質塗工部と負極板の活物質塗工部とセパレータとが平面状をなして電極体の厚み方向に積層された部位をいう。また、上端側発電弧状部とは、リチウムイオン二次電池の使用時において、発電部の鉛直方向上端側に位置し（鉛直方向上端部をなし）、正極板の活物質塗工部と負極板の活物質塗工部とセパレータとが弧状をなして重なる部位をいう。また、下端側発電弧状部とは、リチウムイオン二次電池の使用時において、発電部の鉛直方向下端側に位置し（鉛直方向下端部をなし）、正極板の活物質塗工部と負極板の活物質塗工部とセパレータとが弧状をなして重なる部位をいう。 The power generation flat part is a part of the power generation part in which the active material coating part of the positive electrode plate, the active material coating part of the negative electrode plate, and the separator are laminated in the thickness direction of the electrode body. Say. In addition, the upper end side power generation arc-shaped part is located on the upper end side in the vertical direction of the power generation part when the lithium ion secondary battery is used (the upper end part in the vertical direction is formed), and the active material coating part and the negative electrode plate of the positive electrode plate The active material coating portion and the separator overlap each other in an arc shape. In addition, the lower end side power generation arc-shaped part is located on the lower end side in the vertical direction of the power generation part when using the lithium ion secondary battery (the lower end part in the vertical direction is formed), and the active material coating part and the negative electrode plate of the positive electrode plate The active material coating portion and the separator overlap each other in an arc shape.
　さらに、上記のリチウムイオン二次電池であって、前記上端側発電弧状部に含まれる前記非水電解液の前記Ｌｉ塩の濃度は、前記発電平坦部及び前記下端側発電弧状部に含まれる前記非水電解液の前記Ｌｉ塩の濃度よりも、０．２ｍｏｌ／Ｌ以上高くされてなるリチウムイオン二次電池とすると良い。 Furthermore, in the above lithium ion secondary battery, the concentration of the Li salt in the non-aqueous electrolyte contained in the upper end side power generation arc-shaped portion is included in the power generation flat portion and the lower end side power generation arc shape portion. A lithium ion secondary battery that is made 0.2 mol / L or more higher than the concentration of the Li salt in the non-aqueous electrolyte is preferable.
　充電または放電の電流値を大きくする（ハイレートにする）ほど、発電平坦部の一部における非水電解液中のＬｉイオン（Ｌｉ塩）の減少量は大きくなる。従って、従来のリチウムイオン二次電池について、例えば、２０Ｃ程度の極めて大きい電流値（ハイレート）で充電または放電を繰り返し行った場合（例えば、電池電圧が上限電圧値から下限電圧値に至るまで２０Ｃのハイレートで放電を行い、その後、電池電圧が上限電圧値に至るまで１Ｃで充電を行う充放電サイクルを繰り返し行った場合）には、リチウムイオン二次電池の内部抵抗が大きく上昇してしまう（例えば、初期値の約５倍にまで上昇することがある）。従って、このような場合でもリチウムイオン二次電池の内部抵抗の上昇を抑制するためには、上端側発電弧状部に含まれる非水電解液のＬｉ塩の濃度を、発電平坦部及び下端側発電弧状部に含まれる非水電解液のＬｉ塩の濃度よりも、ある程度以上高くする必要がある。 As the current value of charging or discharging is increased (higher rate), the amount of reduction of Li ions (Li salt) in the non-aqueous electrolyte in a part of the power generation flat portion increases. Therefore, when a conventional lithium ion secondary battery is repeatedly charged or discharged at an extremely large current value (high rate) of, for example, about 20 C (for example, 20 C until the battery voltage reaches the lower limit voltage value from the upper limit voltage value). When the battery is discharged at a high rate and then repeatedly charged and discharged at 1C until the battery voltage reaches the upper limit voltage value, the internal resistance of the lithium ion secondary battery is greatly increased (for example, May increase to about 5 times the initial value). Therefore, even in such a case, in order to suppress an increase in the internal resistance of the lithium ion secondary battery, the concentration of the Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is changed to the power generation flat portion and the lower-end side power generation. It is necessary to make it higher than a certain level than the concentration of Li salt in the non-aqueous electrolyte contained in the arcuate portion.
　これに対し、上述のリチウムイオン二次電池では、上端側発電弧状部に含まれる非水電解液のＬｉ塩の濃度を、発電平坦部及び下端側発電弧状部に含まれる非水電解液のＬｉ塩の濃度よりも、０．２ｍｏｌ／Ｌ以上高くしている。これにより、２０Ｃ程度の極めて高い電流値（ハイレート）で充電または放電を繰り返し行った場合でも、上端側発電弧状部から流れ落ちてくる非水電解液によって、発電平坦部のＬｉイオンが減少してゆく部位に、Ｌｉイオンを効率よく供給することができる。これにより、発電平坦部の一部において非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下することを防止できる。さらには、発電平坦部における非水電解液のＬｉイオン濃度の偏りの程度（Ｌｉイオン濃度が高い部位と低い部位との濃度差）を小さくすることができる。従って、リチウムイオン二次電池の内部抵抗の上昇を抑制することができる。 On the other hand, in the above-described lithium ion secondary battery, the concentration of Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is set to the Li salt of the non-aqueous electrolyte contained in the power-generation flat portion and the lower-end power generation arc-shaped portion. It is higher than the salt concentration by 0.2 mol / L or more. Thereby, even when charging or discharging is repeatedly performed at an extremely high current value (high rate) of about 20 C, Li ions in the power generation flat portion are reduced by the nonaqueous electrolyte flowing down from the upper end side power generation arc-shaped portion. Li ions can be efficiently supplied to the site. Thereby, it is possible to prevent the Li ion concentration (Li salt concentration) of the nonaqueous electrolytic solution from greatly decreasing in a part of the power generation flat portion. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion (concentration difference between the portion where the Li ion concentration is high and the portion where it is low) can be reduced. Therefore, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
　さらに、上記いずれかのリチウムイオン二次電池であって、前記リチウムイオン二次電池は、１０Ｃ以上で充電または放電が行われるリチウムイオン二次電池とすると良い。 Furthermore, any one of the above lithium ion secondary batteries may be a lithium ion secondary battery that is charged or discharged at 10 C or higher.
　上述のリチウムイオン二次電池では、１０Ｃ以上で充電または放電が行われる。１０Ｃ以上のハイレートで充電または放電が行われる場合は、特に、リチウムイオン二次電池の内部抵抗が上昇し易くなる。
　しかしながら、前述のように、当該リチウムイオン二次電池について、上端側発電弧状部に含まれる非水電解液のＬｉ塩濃度（Ｌｉイオン濃度）を、発電平坦部及び下端側発電弧状部（すなわち、上端側発電弧状部を除いた発電部の他の部位）に含まれる非水電解液のＬｉ塩濃度よりも高くしている。このため、１０Ｃ以上のハイレートで充電または放電が行われる場合でも、リチウムイオン二次電池の内部抵抗の上昇を抑制することができる。 In the above-described lithium ion secondary battery, charging or discharging is performed at 10 C or more. In particular, when charging or discharging is performed at a high rate of 10 C or higher, the internal resistance of the lithium ion secondary battery is likely to increase.
However, as described above, for the lithium ion secondary battery, the Li salt concentration (Li ion concentration) of the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is set to the power generation flat portion and the lower-end power generation arc-shaped portion (that is, The Li salt concentration of the non-aqueous electrolyte contained in the other part of the power generation unit excluding the upper end side power generation arc-shaped part) is set higher. For this reason, even when charging or discharging is performed at a high rate of 10 C or higher, an increase in internal resistance of the lithium ion secondary battery can be suppressed.
　なお、１Ｃは、ＳＯＣ１００％の電池を１時間でＳＯＣ０％まで定電流放電できる電流値である。従って、１０Ｃは、ＳＯＣ１００％の電池を６分でＳＯＣ０％まで放電できる電流値に相当する。ＳＯＣは、State Of Charge（充電状態、充電率）の略である。 Note that 1C is a current value that allows constant current discharge of a battery with 100% SOC to SOC 0% in one hour. Therefore, 10 C corresponds to a current value that can discharge a battery with 100% SOC to SOC 0% in 6 minutes. SOC is an abbreviation for State （Of Charge (charging state, charging rate).
　また、本発明の他の態様は、車両であって、上記いずれかのリチウムイオン二次電池を、当該車両の駆動用電源として搭載してなる車両である。 Further, another aspect of the present invention is a vehicle in which any one of the above lithium ion secondary batteries is mounted as a driving power source for the vehicle.
　上述の車両は、前記いずれかのリチウムイオン二次電池を、当該車両の駆動用電源として搭載している。前述のように、前記のリチウムイオン二次電池は、当該電池の内部抵抗の上昇を抑制することができるリチウムイオン二次電池である。このため、上述の車両では、駆動用電源であるリチウムイオン二次電池の内部抵抗の上昇を抑制することができるので、駆動用電源（リチウムイオン二次電池）の出力低下を抑制することができる。従って、上述の車両では、走行性能の低下を抑制することができる。 The vehicle described above is equipped with one of the lithium ion secondary batteries as a power source for driving the vehicle. As described above, the lithium ion secondary battery is a lithium ion secondary battery that can suppress an increase in internal resistance of the battery. For this reason, in the above-described vehicle, an increase in the internal resistance of the lithium ion secondary battery, which is a driving power source, can be suppressed, so that a decrease in the output of the driving power source (lithium ion secondary battery) can be suppressed. . Therefore, in the above-described vehicle, it is possible to suppress a decrease in traveling performance.
　特に、電気自動車やハイブリッド自動車の駆動用電源として搭載されたリチウムイオン二次電池は、ハイレートで充電または放電が行われることが多いので、内部抵抗が上昇し易い環境にある。しかしながら、上述のように、駆動用電源であるリチウムイオン二次電池の内部抵抗の上昇を抑制することができるので、電気自動車やハイブリッド自動車についても、駆動用電源の出力低下を抑制することができる。このため、電気自動車やハイブリッド自動車についても、走行性能の低下を抑制することができる。 Especially, a lithium ion secondary battery mounted as a driving power source for an electric vehicle or a hybrid vehicle is often charged or discharged at a high rate, so that the internal resistance tends to increase. However, as described above, an increase in the internal resistance of the lithium ion secondary battery that is a driving power source can be suppressed, so that a decrease in the output of the driving power source can also be suppressed for electric vehicles and hybrid vehicles. . For this reason, also about an electric vehicle and a hybrid vehicle, the fall of driving performance can be suppressed.
実施形態にかかる車両（ハイブリッド自動車）の概略図である。1 is a schematic view of a vehicle (hybrid vehicle) according to an embodiment. 実施形態にかかるリチウムイオン二次電池の縦断面図である。It is a longitudinal cross-sectional view of the lithium ion secondary battery concerning embodiment. 実施形態にかかるリチウムイオン二次電池の電極体の斜視図である。It is a perspective view of the electrode body of the lithium ion secondary battery concerning embodiment. 同電極体の発電部の縦断面図である。It is a longitudinal cross-sectional view of the electric power generation part of the same electrode body. 同発電部の部分拡大断面図であり、図４のＢ部拡大図に相当する。It is the elements on larger scale of the electric power generation part, and is equivalent to the B section enlarged view of FIG. サイクル充放電に伴うリチウムイオン二次電池の内部抵抗の変動を示す図である。It is a figure which shows the fluctuation | variation of the internal resistance of the lithium ion secondary battery accompanying cycle charging / discharging. 実施形態にかかるリチウムイオン二次電池の正極板を示す図である。It is a figure which shows the positive electrode plate of the lithium ion secondary battery concerning embodiment. 実施形態にかかるリチウムイオン二次電池の負極板を示す図である。It is a figure which shows the negative electrode plate of the lithium ion secondary battery concerning embodiment. 正極板、負極板、及び、セパレータを積層して、捲回する工程を説明する図である。It is a figure explaining the process of laminating | stacking and winding a positive electrode plate, a negative electrode plate, and a separator. 電極収容体の縦断面図である。It is a longitudinal cross-sectional view of an electrode container. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment. 実施形態にかかる電解液注入方法を説明する図である。It is a figure explaining the electrolyte solution injection method concerning an embodiment.
　次に、本発明の実施形態について、図面を参照しつつ説明する。
　本実施形態にかかる車両１は、図１に示すように、車体２、エンジン３、フロントモータ４、リヤモータ５、組電池１０、及びケーブル７を有し、エンジン３とフロントモータ４及びリヤモータ５との併用で駆動するハイブリッド自動車である。具体的には、この車両１は、組電池１０をフロントモータ４及びリヤモータ５の駆動用電源として、公知の手段により、エンジン３とフロントモータ４及びリヤモータ５とを用いて走行できるように構成されている。 Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the vehicle 1 according to the present embodiment includes a vehicle body 2, an engine 3, a front motor 4, a rear motor 5, an assembled battery 10, and a cable 7, and the engine 3, the front motor 4, the rear motor 5, and the like. It is a hybrid car that is driven in combination. Specifically, the vehicle 1 is configured to be able to travel using the engine 3, the front motor 4, and the rear motor 5 by known means using the assembled battery 10 as a driving power source for the front motor 4 and the rear motor 5. ing.
　このうち、組電池１０は、車両１の車体２に取り付けられており、ケーブル７によりフロントモータ４及びリヤモータ５に接続されている。この組電池１０は、電気的に直列に接続された複数（例えば、１００個）のリチウムイオン二次電池１００を有している。組電池１０を構成するリチウムイオン二次電池１００は、図示しない制御装置により、充放電が制御される。ハイブリッド自動車である車両１では、急加速等する場合、１０Ｃ以上でリチウムイオン二次電池１００の放電が行われる。 Among these, the assembled battery 10 is attached to the vehicle body 2 of the vehicle 1 and is connected to the front motor 4 and the rear motor 5 by a cable 7. This assembled battery 10 has a plurality (for example, 100) of lithium ion secondary batteries 100 electrically connected in series. Charging / discharging of the lithium ion secondary battery 100 constituting the assembled battery 10 is controlled by a control device (not shown). In the vehicle 1 which is a hybrid vehicle, the lithium ion secondary battery 100 is discharged at 10 C or higher when sudden acceleration or the like is performed.
　リチウムイオン二次電池１００は、図２に示すように、直方体形状の電池ケース１１０と、正極外部端子１２１と、負極外部端子１３１とを備える、角形密閉式のリチウムイオン二次電池である。このうち、電池ケース１１０は、直方体形状の収容空間をなす金属製の角形収容部１１１と金属製の蓋部１１２とを有するハードケースである。電池ケース１１０（角形収容部１１１）の内部には、電極体１５０などが収容されている。 As shown in FIG. 2, the lithium ion secondary battery 100 is a rectangular sealed lithium ion secondary battery including a rectangular parallelepiped battery case 110, a positive electrode external terminal 121, and a negative electrode external terminal 131. Among these, the battery case 110 is a hard case having a metal rectangular housing part 111 and a metal lid part 112 forming a rectangular parallelepiped housing space. An electrode body 150 and the like are housed inside the battery case 110 (the square housing portion 111).
　なお、図２では、電極体１５０の軸線方向をＸで表している。また、鉛直方向をＹで表している。他の図面においても同様である。また、図２は、リチウムイオン二次電池１００の使用時における姿勢での縦断面図である。従って、リチウムイオン二次電池１００は、後述するように、電極体１５０の発電部１６０について、上端側発電弧状部１６１を鉛直方向上側に、下端側発電弧状部１６３を鉛直方向下側にして使用される（充放電が行われる）。 In FIG. 2, the axial direction of the electrode body 150 is represented by X. The vertical direction is indicated by Y. The same applies to other drawings. FIG. 2 is a vertical cross-sectional view of the lithium ion secondary battery 100 in a posture during use. Therefore, as will be described later, the lithium ion secondary battery 100 uses the power generation unit 160 of the electrode body 150 with the upper end side power generation arc-shaped portion 161 on the upper side in the vertical direction and the lower end side power generation arc-shaped portion 163 on the lower side in the vertical direction. (Charging / discharging is performed).
　電極体１５０は、断面長円状をなし、シート状の正極板１５５、負極板１５６、及びセパレータ１５７を扁平形状に捲回した扁平型の捲回体である（図３，図４参照）。正極板１５５は、アルミニウム箔からなる正極集電部材１５１と、その表面に塗工された正極合剤１５２（正極活物質１５３を含む合剤）を有している（図５参照）。負極板１５６は、銅箔からなる負極集電部材１５８と、その表面に塗工された負極合剤１５９（負極活物質１５４を含む合剤）を有している（図５参照）。 The electrode body 150 is an oblong cross section, and is a flat wound body in which a sheet-like positive electrode plate 155, a negative electrode plate 156, and a separator 157 are wound into a flat shape (see FIGS. 3 and 4). The positive electrode plate 155 has a positive electrode current collecting member 151 made of an aluminum foil and a positive electrode mixture 152 (a mixture containing the positive electrode active material 153) applied on the surface thereof (see FIG. 5). The negative electrode plate 156 has a negative electrode current collecting member 158 made of copper foil and a negative electrode mixture 159 (a mixture containing the negative electrode active material 154) coated on the surface thereof (see FIG. 5).
　この電極体１５０は、図２及び図３に示すように、発電部１６０と正極捲回部１５０ｄと負極捲回部１５０ｃとにより構成される。 2 and 3, the electrode body 150 includes a power generation unit 160, a positive electrode winding unit 150d, and a negative electrode winding unit 150c.
　正極捲回部１５０ｄは、電極体１５０の軸線方向Ｘ（図２において左右方向）について発電部１６０の一方側（図２において右側）に隣り合い、正極板１５５のうち正極集電部材１５１の表面に正極合剤１５２が塗工されていない正極活物質未塗工部１５５ｂのみが重なり合う部位である。
　負極捲回部１５０ｃは、電極体１５０の軸線方向Ｘ（図２において左右方向）について発電部１６０の他方側（図２において左側）に隣り合い、負極板１５６のうち負極集電部材１５８の表面に負極合剤１５９が塗工されていない負極活物質未塗工部１５６ｂのみが重なり合う部位である。 The positive electrode winding part 150d is adjacent to one side (right side in FIG. 2) of the power generation part 160 in the axial direction X (left and right direction in FIG. 2) of the electrode body 150, and the surface of the positive electrode current collecting member 151 in the positive electrode plate 155. This is a portion where only the positive electrode active material uncoated portion 155b where the positive electrode mixture 152 is not coated overlaps.
The negative electrode winding part 150c is adjacent to the other side (left side in FIG. 2) of the power generation part 160 in the axial direction X (left and right direction in FIG. 2) of the electrode body 150, and the surface of the negative electrode current collecting member 158 in the negative electrode plate 156 This is a portion where only the negative electrode active material uncoated portion 156b where the negative electrode mixture 159 is not coated overlaps.
　正極捲回部１５０ｄは、正極集電部１２２を通じて、正極外部端子１２１に電気的に接続されている（図２参照）。負極捲回部１５０ｃは、負極集電部１３２を通じて、負極外部端子１３１に電気的に接続されている。なお、正極外部端子１２１と正極集電部１２２とは一体に形成され、正極集電端子部材１２０を構成している。また、負極外部端子１３１と負極集電部１３２とは一体に形成され、負極集電端子部材１３０を構成している。 The positive electrode winding unit 150d is electrically connected to the positive electrode external terminal 121 through the positive electrode current collector 122 (see FIG. 2). The negative electrode winding unit 150 c is electrically connected to the negative electrode external terminal 131 through the negative electrode current collector 132. The positive electrode external terminal 121 and the positive electrode current collector 122 are integrally formed to constitute the positive electrode current collector terminal member 120. Further, the negative electrode external terminal 131 and the negative electrode current collector 132 are integrally formed to constitute the negative electrode current collector terminal member 130.
　発電部１６０は、正極板１５５のうち正極集電部材１５１の表面に正極合剤１５２が塗工されている正極活物質塗工部１５５ｃと、負極板１５６のうち負極集電部材１５８の表面に負極合剤１５９が塗工されている負極活物質塗工部１５６ｃと、セパレータ１５７とが重なり合う部位である（図４，図５参照）。この発電部１６０は、発電部１６０の上端部をなす上端側発電弧状部１６１と、発電部１６０の下端部をなす下端側発電弧状部１６３と、上端側発電弧状部１６１と下端側発電弧状部１６３との間に位置する発電平坦部１６２とからなる（図２～図４参照）。 The power generation unit 160 includes a positive electrode active material coating unit 155c in which the positive electrode mixture 152 is coated on the surface of the positive electrode current collecting member 151 in the positive electrode plate 155 and a negative electrode current collecting member 158 in the negative electrode plate 156. This is a portion where the negative electrode active material coating part 156c coated with the negative electrode mixture 159 and the separator 157 overlap (see FIGS. 4 and 5). The power generation unit 160 includes an upper end power generation arc-shaped portion 161 that forms the upper end of the power generation unit 160, a lower end side power generation arc-shaped portion 163 that forms the lower end of the power generation unit 160, and an upper end side power generation arc-shaped portion 161 and a lower end side power generation arc-shaped portion. And a power generation flat part 162 located between the two parts (see FIGS. 2 to 4).
　発電平坦部１６２は、発電部１６０のうち、正極活物質塗工部１５５ｃと負極活物質塗工部１５６ｃとセパレータ１５７とが平面状をなして電極体１５０の厚み方向（図４において左右方向）に積層された部位である。また、上端側発電弧状部１６１は、リチウムイオン二次電池１００の使用時において、発電部１６０の鉛直方向（Ｙ方向、図２，図４において上下方向）上端側に位置し（図２参照）、正極活物質塗工部１５５ｃと負極活物質塗工部１５６ｃとセパレータ１５７とが弧状をなして重なる部位である。また、下端側発電弧状部１６３は、リチウムイオン二次電池１００の使用時において、発電部１６０の鉛直方向（Ｙ方向、図２，図４において上下方向）下端側に位置し（図２参照）、正極活物質塗工部１５５ｃと負極活物質塗工部１５６ｃとセパレータ１５７とが弧状をなして重なる部位である。 In the power generation flat portion 162, the positive electrode active material coating portion 155c, the negative electrode active material coating portion 156c, and the separator 157 in the power generation portion 160 form a planar shape, and the thickness direction of the electrode body 150 (the left-right direction in FIG. 4). It is the part laminated | stacked on. Further, the upper end side power generation arc-shaped portion 161 is located on the upper end side in the vertical direction (Y direction, vertical direction in FIGS. 2 and 4) of the power generation unit 160 when the lithium ion secondary battery 100 is used (see FIG. 2). The positive electrode active material coating part 155c, the negative electrode active material coating part 156c, and the separator 157 overlap each other in an arc shape. Moreover, the lower end side power generation arc-shaped part 163 is located on the lower end side in the vertical direction (Y direction, vertical direction in FIGS. 2 and 4) of the power generation unit 160 when the lithium ion secondary battery 100 is used (see FIG. 2). The positive electrode active material coating part 155c, the negative electrode active material coating part 156c, and the separator 157 overlap each other in an arc shape.
　なお、本実施形態では、正極活物質１５３としてニッケル酸リチウムを用いている。また、負極活物質１５４として、天然黒鉛を用いている。また、セパレータ１５７として、ポリプロピレン／ポリエチレン／ポリプロピレン３層構造複合体多孔質シートを用いている。 In this embodiment, lithium nickelate is used as the positive electrode active material 153. Further, natural graphite is used as the negative electrode active material 154. In addition, a polypropylene / polyethylene / polypropylene three-layer structure composite porous sheet is used as the separator 157.
　また、発電部１６０の内部には、Ｌｉ塩を含有する非水電解液が含まれている。但し、本実施形態では、発電部１６０の内部に、Ｌｉ塩の濃度が異なる２種類の非水電解液（第１非水電解液１４０Ｂと第２非水電解液１４０Ｃ）を含有させている。具体的には、上端側発電弧状部１６１に第１非水電解液１４０Ｂを含有させ、発電平坦部１６２及び下端側発電弧状部１６３に第２非水電解液１４０Ｃを含有させている（図２，図４参照）。 Moreover, the non-aqueous electrolyte containing Li salt is contained in the power generation unit 160. However, in the present embodiment, the power generation unit 160 contains two types of non-aqueous electrolytes (first non-aqueous electrolyte 140B and second non-aqueous electrolyte 140C) having different Li salt concentrations. Specifically, the first non-aqueous electrolyte 140B is included in the upper end side power generation arc-shaped portion 161, and the second non-aqueous electrolyte 140C is included in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163 (FIG. 2). FIG. 4).
　本実施形態では、第１非水電解液１４０ＢのＬｉ塩の濃度を、第２非水電解液１４０ＣのＬｉ塩の濃度よりも高くしている。具体的には、第１非水電解液１４０ＢのＬｉ塩の濃度を１．２ｍｏｌ／Ｌとし、第２非水電解液１４０ＣのＬｉ塩濃度を１．０ｍｏｌ／Ｌとしている。このように、本実施形態では、上端側発電弧状部１６１に含まれる非水電解液１４０ＢのＬｉ塩の濃度を、発電平坦部１６２及び下端側発電弧状部１６３に含まれる非水電解液１４０ＣのＬｉ塩の濃度よりも高くしている。 In the present embodiment, the concentration of the Li salt in the first nonaqueous electrolyte solution 140B is set higher than the concentration of the Li salt in the second nonaqueous electrolyte solution 140C. Specifically, the concentration of the Li salt in the first nonaqueous electrolytic solution 140B is 1.2 mol / L, and the concentration of the Li salt in the second nonaqueous electrolytic solution 140C is 1.0 mol / L. As described above, in this embodiment, the concentration of the Li salt in the nonaqueous electrolyte solution 140B included in the upper end side power generation arc-shaped portion 161 is set to be equal to that of the nonaqueous electrolyte solution 140C included in the power generation flat portion 162 and the lower end side power generation arc shape portion 163. It is higher than the concentration of Li salt.
　ところで、ハイブリッド自動車の駆動用電源として搭載されたリチウムイオン二次電池は、ハイレート（例えば、１０Ｃ以上）で充電または放電が行われることが多い。リチウムイオン二次電池について、ハイレートの充電または放電を繰り返し行うと、発電平坦部の一部において非水電解液中のＬｉイオン（Ｌｉ塩）が減少してゆく。これにより、発電平坦部において非水電解液のＬｉイオン濃度に偏りが生じ、リチウムイオン二次電池の内部抵抗が上昇する。特に、発電平坦部の一部において非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下すると、リチウムイオン二次電池の内部抵抗が大きく上昇する（図６の比較形態を参照）。 Incidentally, a lithium ion secondary battery mounted as a driving power source for a hybrid vehicle is often charged or discharged at a high rate (for example, 10 C or more). When lithium ion secondary batteries are repeatedly charged or discharged at a high rate, Li ions (Li salts) in the non-aqueous electrolyte decrease in part of the power generation flat portion. As a result, the Li ion concentration of the non-aqueous electrolyte is biased in the power generation flat portion, and the internal resistance of the lithium ion secondary battery is increased. In particular, when the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte is greatly reduced in a part of the power generation flat portion, the internal resistance of the lithium ion secondary battery is greatly increased (see the comparison form in FIG. 6).
　また、本願発明者の研究調査により、正極板、負極板、及びセパレータを扁平形状に捲回した電極体を備えるリチウムイオン二次電池について、ハイレートの充電または放電を繰り返し行うと、上端側発電弧状部に含まれている非水電解液の一部が、発電平坦部に流れ落ちることが判明した。この現象は、次のようにして起こると考えられる。リチウムイオン二次電池についてハイレートの充電または放電を繰り返し行うことで、上端側発電弧状部が膨張と収縮を繰り返す。これ（膨張と収縮によるポンプ効果）により、上端側発電弧状部に含まれている非水電解液の一部が上端側発電弧状部から押し出され、重力によって、上端側発電弧状部の下方に位置する発電平坦部に流れ落ちると考えられる。 Further, according to the research of the present inventor, the lithium ion secondary battery including the positive electrode plate, the negative electrode plate, and the electrode body obtained by winding the separator in a flat shape is repeatedly subjected to high-rate charging or discharging, and the upper end side power generation arc shape It was found that a part of the non-aqueous electrolyte contained in the part flows down to the power generation flat part. This phenomenon is considered to occur as follows. By repeatedly performing high-rate charging or discharging on the lithium ion secondary battery, the upper end side power generation arc-shaped portion repeatedly expands and contracts. Due to this (pumping effect due to expansion and contraction), a part of the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is pushed out of the upper-end-side power generation arc-shaped portion and is positioned below the upper-end-side power generation arc-shaped portion by gravity. It is thought that it flows down to the power generation flat part.
　これに対し、本実施形態のリチウムイオン二次電池１００では、上述のように、上端側発電弧状部１６１に含まれる非水電解液１４０ＢのＬｉ塩の濃度を、発電平坦部１６２及び下端側発電弧状部１６３に含まれる非水電解液１４０ＣのＬｉ塩の濃度よりも高くしている。これにより、ハイレートの充電または放電が繰り返し行われることで、発電平坦部１６２の一部において非水電解液１４０Ｃ中のＬｉイオン（Ｌｉ塩）が減少してゆく場合でも、上端側発電弧状部１６１から流れ落ちてきたＬｉイオン濃度（Ｌｉ塩濃度）の高い非水電解液１４０Ｂによって、Ｌｉイオンが減少してゆく部位にＬｉイオンを効率よく供給することができる。 On the other hand, in the lithium ion secondary battery 100 of the present embodiment, as described above, the concentration of the Li salt of the non-aqueous electrolyte 140B included in the upper end side power generation arc-shaped portion 161 is changed to the power generation flat portion 162 and the lower end side power generation. The concentration is higher than the concentration of Li salt in the non-aqueous electrolyte solution 140C contained in the arc-shaped portion 163. Thereby, even when Li-ion (Li salt) in the non-aqueous electrolyte 140C decreases in a part of the power generation flat portion 162 by repeatedly performing high-rate charging or discharging, the upper-end-side power generation arc-shaped portion 161 Li ion can be efficiently supplied to the site where the Li ions are decreased by the non-aqueous electrolyte solution 140B having a high Li ion concentration (Li salt concentration) that has flowed down.
　これにより、発電平坦部１６２の一部において非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下することを防止できる。さらには、発電平坦部１６２における非水電解液のＬｉイオン濃度の偏りの程度（Ｌｉイオン濃度が高い部位と低い部位との濃度差）を小さくすることができる。このため、リチウムイオン二次電池１００の内部抵抗の上昇を抑制することができる（図６の実施形態を参照）。これにより、ハイブリッド自動車である車両１について、駆動用電源（複数のリチウムイオン二次電池１００を直列接続した組電池１０）の出力低下を抑制することができるので、走行性能の低下を抑制することができる。 Thereby, it is possible to prevent the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte from greatly decreasing in a part of the power generation flat portion 162. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion 162 (concentration difference between the portion where the Li ion concentration is high and the portion where the Li ion concentration is low) can be reduced. For this reason, the raise of the internal resistance of the lithium ion secondary battery 100 can be suppressed (refer embodiment of FIG. 6). Thereby, about the vehicle 1 which is a hybrid vehicle, since the output fall of the drive power supply (assembled battery 10 which connected the some lithium ion secondary battery 100 in series) can be suppressed, the fall of driving performance is suppressed. Can do.
　なお、本実施形態では、非水電解液１４０Ｂ，１４０Ｃとして、ＥＣ（エチレンカーボネート）とＤＭＣ（ジメチルカーボネート）とＥＭＣ（エチルメチルカーボネート）とを混合した非水溶媒中に、Ｌｉ塩である六フッ化燐酸リチウム（ＬｉＰＦ６）を溶解した非水電解液を用いている。但し、第１非水電解液１４０Ｂでは、Ｌｉ塩（ＬｉＰＦ６）の濃度を１．２ｍｏｌ／Ｌとしている。一方、第２非水電解液１４０Ｃでは、Ｌｉ塩（ＬｉＰＦ６）の濃度を１．０ｍｏｌ／Ｌとしている。 In the present embodiment, as the non-aqueous electrolytes 140B and 140C, six fluorides, which are Li salts, are mixed in a non-aqueous solvent in which EC (ethylene carbonate), DMC (dimethyl carbonate), and EMC (ethyl methyl carbonate) are mixed. A nonaqueous electrolytic solution in which lithium phosphate (LiPF 6 ) is dissolved is used. However, in the first non-aqueous electrolyte solution 140B, the concentration of Li salt (LiPF 6 ) is set to 1.2 mol / L. On the other hand, in the second nonaqueous electrolytic solution 140C, the concentration of Li salt (LiPF 6 ) is 1.0 mol / L.
（サイクル充放電試験）
　本実施形態のリチウムイオン二次電池１００について、充放電サイクル試験を行った。具体的には、まず、リチウムイオン二次電池１００の電池電圧が下限電圧値（具体的には、２．０Ｖ）に達するまで（換言すれば、リチウムイオン二次電池１００がＳＯＣ０％に達するまで）、２０Ｃ（ハイレート）の定電流で放電を行う。その後、電池電圧が上限電圧値（具体的には、４．１Ｖ）に達するまで（換言すれば、リチウムイオン二次電池１００がＳＯＣ１００％に達するまで）、１Ｃの定電流で充電を行った。この充放電サイクルを１サイクルとして、リチウムイオン二次電池１００について、７０００サイクルの充放電を行った。 (Cycle charge / discharge test)
A charge / discharge cycle test was performed on the lithium ion secondary battery 100 of the present embodiment. Specifically, first, until the battery voltage of the lithium ion secondary battery 100 reaches the lower limit voltage value (specifically, 2.0 V) (in other words, until the lithium ion secondary battery 100 reaches SOC 0%). ), Discharge at a constant current of 20 C (high rate). Thereafter, the battery was charged with a constant current of 1 C until the battery voltage reached an upper limit voltage value (specifically, 4.1 V) (in other words, until the lithium ion secondary battery 100 reached 100% SOC). With this charge / discharge cycle as one cycle, the lithium ion secondary battery 100 was charged / discharged for 7000 cycles.
　なお、１Ｃは、ＳＯＣ１００％の電池を１時間でＳＯＣ０％まで定電流放電できる電流値である。従って、２０Ｃは、ＳＯＣ１００％の電池を３分でＳＯＣ０％まで放電できる電流値に相当する。ＳＯＣは、State Of Charge（充電状態、充電率）の略である。 Note that 1C is a current value that allows constant current discharge of a battery with 100% SOC to SOC 0% in one hour. Therefore, 20 C corresponds to a current value that can discharge a battery with 100% SOC to SOC 0% in 3 minutes. SOC is an abbreviation for State （Of Charge (charging state, charging rate).
　また、実施形態のリチウムイオン二次電池１００と比較して、非水電解液のみが異なる比較形態のリチウムイオン二次電池を用意した。具体的には、比較形態のリチウムイオン二次電池では、非水電解液として、第２非水電解液１４０Ｃのみを用いている。従って、、比較形態のリチウムイオン二次電池では、発電平坦部及び下端側発電弧状部のみならず、上端側発電弧状部にも、非水電解液１４０Ｃを含有させている。すなわち、比較形態のリチウムイオン二次電池では、発電部全体に、Ｌｉ塩（ＬｉＰＦ６）の濃度が１．０ｍｏｌ／Ｌである非水電解液１４０Ｃを含有させている。この比較形態のリチウムイオン二次電池についても、実施形態のリチウムイオン二次電池１００と同様にして、７０００サイクルの充放電を行った。 Moreover, compared with the lithium ion secondary battery 100 of embodiment, the lithium ion secondary battery of the comparative form from which only a nonaqueous electrolyte solution differs was prepared. Specifically, in the comparative lithium ion secondary battery, only the second non-aqueous electrolyte 140C is used as the non-aqueous electrolyte. Therefore, in the lithium ion secondary battery of the comparative form, not only the power generation flat portion and the lower end side power generation arc-shaped portion but also the upper end side power generation arc-shaped portion contains the non-aqueous electrolyte 140C. That is, in the comparative lithium ion secondary battery, the entire power generation unit contains the non-aqueous electrolyte solution 140C having a concentration of Li salt (LiPF 6 ) of 1.0 mol / L. The lithium ion secondary battery of this comparative form was also charged and discharged for 7000 cycles in the same manner as the lithium ion secondary battery 100 of the embodiment.
　本サイクル充放電試験では、２００サイクル毎に、実施形態のリチウムイオン二次電池１００と比較形態のリチウムイオン二次電池について、内部抵抗値（具体的には、ＩＶ抵抗値）を測定した。この結果を図６に示す。なお、図６では、実施形態のリチウムイオン二次電池１００の内部抵抗の初期値（サイクル充放電を行う前のＩＶ抵抗値）を１として、各内部抵抗値を相対値で表している。 In this cycle charge / discharge test, the internal resistance value (specifically, the IV resistance value) of the lithium ion secondary battery 100 of the embodiment and the lithium ion secondary battery of the comparative example was measured every 200 cycles. The result is shown in FIG. In FIG. 6, each internal resistance value is expressed as a relative value, where the initial value of the internal resistance of the lithium ion secondary battery 100 of the embodiment (IV resistance value before cycle charge / discharge) is 1.
　なお、ＩＶ抵抗値は、次のようにして算出した。まず、各リチウムイオン二次電池について、電池電圧（端子間電圧ＶＡ）を測定する。その後、各リチウムイオン二次電池について、１Ｃの定電流で１０秒間放電させ、放電後の電池電圧（端子間電圧ＶＢ）を測定する。そして、定電流放電前後の端子間電圧差（ＶＡ－ＶＢ）を、放電電流値で除して、ＩＶ抵抗値を得た。 The IV resistance value was calculated as follows. First, the battery voltage (terminal voltage VA) is measured for each lithium ion secondary battery. Thereafter, each lithium ion secondary battery is discharged at a constant current of 1 C for 10 seconds, and the battery voltage after discharge (terminal voltage VB) is measured. The voltage difference between terminals before and after constant current discharge (VA-VB) was divided by the discharge current value to obtain an IV resistance value.
　図６に示すように、実施形態のリチウムイオン二次電池１００と比較形態のリチウムイオン二次電池とは、内部抵抗の初期値（サイクル充放電を行う前のＩＶ抵抗値）が同等であった。しかしながら、サイクル充放電を行うと、比較形態のリチウムイオン二次電池のほうが、実施形態のリチウムイオン二次電池１００の内部抵抗よりも大きくなった。 As shown in FIG. 6, the lithium ion secondary battery 100 of the embodiment and the lithium ion secondary battery of the comparative embodiment had the same internal resistance initial value (IV resistance value before performing cycle charge / discharge). . However, when cycle charging / discharging was performed, the internal resistance of the lithium ion secondary battery of the comparative example was larger than the internal resistance of the lithium ion secondary battery 100 of the exemplary embodiment.
　具体的には、比較形態のリチウムイオン二次電池では、サイクル充放電を開始してから内部抵抗が大きく上昇していった。そして、１８００サイクルの充放電を行った時点で内部抵抗が最大となり、初期値の４．７倍にまで上昇した。
　これに対し、実施形態のリチウムイオン二次電池１００では、サイクル充放電を開始してから内部抵抗は上昇していったが、その上昇率は、比較形態のリチウムイオン二次電池よりもかなり小さくなった。そして、１８００サイクルの充放電を行った時点で内部抵抗が最大となり、初期値の２．６倍になった。 Specifically, in the lithium ion secondary battery of the comparative form, the internal resistance greatly increased after the start of cycle charge / discharge. When 1800 cycles of charging / discharging were performed, the internal resistance reached the maximum and increased to 4.7 times the initial value.
In contrast, in the lithium ion secondary battery 100 of the embodiment, the internal resistance increased after the start of cycle charge / discharge, but the rate of increase was considerably smaller than that of the comparative lithium ion secondary battery. became. When 1800 cycles of charging / discharging were performed, the internal resistance reached the maximum, which was 2.6 times the initial value.
　内部抵抗の最大値を比較すると、実施形態のリチウムイオン二次電池１００では、比較形態のリチウムイオン二次電池の内部抵抗の約１／２となった。この結果より、実施形態のリチウムイオン二次電池１００では、比較形態のリチウムイオン二次電池に比べて、内部抵抗の上昇を大きく抑制することができたといえる。 Comparing the maximum value of the internal resistance, the lithium ion secondary battery 100 of the embodiment was about ½ of the internal resistance of the lithium ion secondary battery of the comparative form. From this result, it can be said that in the lithium ion secondary battery 100 of the embodiment, an increase in the internal resistance was greatly suppressed as compared with the lithium ion secondary battery of the comparative form.
　１８００サイクル以降、実施形態のリチウムイオン二次電池１００と比較形態のリチウムイオン二次電池は、共に、内部抵抗が低下してゆき、５０００サイクル以降は、ほぼ一定値となった。具体的には、比較形態のリチウムイオン二次電池では、５０００サイクル以降は、内部抵抗が初期値の約２．１倍の値を示した。これに対し、実施形態のリチウムイオン二次電池１００では、５０００サイクル以降は、内部抵抗が初期値の１．５倍の値を示した。 After 1800 cycles, the internal resistance of the lithium ion secondary battery 100 of the embodiment and the lithium ion secondary battery of the comparative example both decreased, and became substantially constant after 5000 cycles. Specifically, in the lithium ion secondary battery of the comparative form, the internal resistance showed a value about 2.1 times the initial value after 5000 cycles. On the other hand, in the lithium ion secondary battery 100 of the embodiment, the internal resistance showed a value 1.5 times the initial value after 5000 cycles.
　５０００サイクル以降の内部抵抗を比較すると、実施形態のリチウムイオン二次電池１００では、比較形態のリチウムイオン二次電池の内部抵抗の約２／３となった。この結果からも、実施形態のリチウムイオン二次電池１００では、比較形態のリチウムイオン二次電池に比べて、内部抵抗の上昇を抑制することができたといえる。
　以上の結果より、実施形態のリチウムイオン二次電池１００は、内部抵抗の上昇を抑制することができるリチウムイオン二次電池であるといえる。 Comparing the internal resistance after 5000 cycles, the lithium ion secondary battery 100 of the embodiment was about 2/3 of the internal resistance of the comparative lithium ion secondary battery. Also from this result, it can be said that the lithium ion secondary battery 100 of the embodiment was able to suppress an increase in internal resistance as compared with the lithium ion secondary battery of the comparative form.
From the above results, it can be said that the lithium ion secondary battery 100 of the embodiment is a lithium ion secondary battery that can suppress an increase in internal resistance.
　実施形態のリチウムイオン二次電池１００において内部抵抗の上昇を抑制することができた理由は、以下のように考えている。
　前述のサイクル充放電試験において、ハイレートの放電（２０Ｃの放電）を繰り返し行うと、電極体１５０をその軸線方向（Ｘ方向）に見たとき（図２参照）、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄに含まれる非水電解液１４０ＣのＬｉイオンの一部が、発電平坦部１６２の軸線方向中央部１６２ｂに移動してゆく。これにより、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄに含まれる非水電解液１４０ＣのＬｉイオン（Ｌｉ塩）が減少してゆく。特に、前述のサイクル充放電試験では、２０Ｃのハイレートで放電を繰り返し行っているので、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄに含まれる非水電解液１４０ＣのＬｉイオン（Ｌｉ塩）の減少量は大きくなる。 The reason why the increase in internal resistance can be suppressed in the lithium ion secondary battery 100 of the embodiment is considered as follows.
When the high-rate discharge (20C discharge) is repeatedly performed in the cycle charge / discharge test described above, when the electrode body 150 is viewed in the axial direction (X direction) (see FIG. 2), both ends in the axial direction of the power generation flat portion 162 A part of the Li ions of the non-aqueous electrolyte 140C included in the parts 162c and 162d moves to the axially central part 162b of the power generation flat part 162. Thereby, Li ion (Li salt) of the non-aqueous electrolyte 140C contained in the axial direction both ends 162c and 162d of the power generation flat portion 162 decreases. In particular, in the above-described cycle charge / discharge test, since discharge is repeatedly performed at a high rate of 20C, the Li ion (Li salt) of the nonaqueous electrolyte 140C contained in the axial end portions 162c and 162d of the power generation flat portion 162 is reduced. The amount of reduction increases.
　しかしながら、実施形態のリチウムイオン二次電池１００では、前述のように、上端側発電弧状部１６１に含まれる第１非水電解液１４０ＢのＬｉ塩の濃度を、発電平坦部１６２及び下端側発電弧状部１６３に含まれる第２非水電解液１４０ＣのＬｉ塩の濃度よりも高くしている。特に、本実施形態では、上端側発電弧状部１６１に含まれる第１非水電解液１４０ＢのＬｉ塩の濃度を、発電平坦部１６２及び下端側発電弧状部１６３に含まれる第２非水電解液１４０ＣのＬｉ塩の濃度よりも、０．２ｍｏｌ／Ｌ以上高くしている。 However, in the lithium ion secondary battery 100 of the embodiment, as described above, the concentration of the Li salt of the first non-aqueous electrolyte 140B included in the upper end side power generation arc-shaped portion 161 is set to the power generation flat portion 162 and the lower end side power generation arc shape. The concentration of Li salt in the second non-aqueous electrolyte solution 140 </ b> C included in the portion 163 is set higher. In particular, in the present embodiment, the concentration of the Li salt in the first non-aqueous electrolyte solution 140B included in the upper end side power generation arc-shaped portion 161 is set to the second non-aqueous electrolyte solution included in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163. It is 0.2 mol / L or more higher than the concentration of the 140C Li salt.
　これにより、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄに含まれる非水電解液１４０ＣのＬｉイオン（Ｌｉ塩）が減少していっても、上端側発電弧状部１６１から流れ落ちてきたＬｉイオン濃度（Ｌｉ塩濃度）の高い非水電解液１４０Ｂによって、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄ（Ｌｉイオンが減少してゆく部位）に、Ｌｉイオンを効率よく供給することができる。 Thereby, even if Li ion (Li salt) of the non-aqueous electrolyte 140C contained in the axial both ends 162c and 162d of the power generation flat portion 162 is decreased, Li ions that have flowed down from the upper end side power generation arc-shaped portion 161 are reduced. The non-aqueous electrolyte solution 140B having a high concentration (Li salt concentration) can efficiently supply Li ions to both axial ends 162c and 162d (sites where Li ions decrease) of the power generation flat portion 162.
　従って、発電平坦部１６２の軸線方向両端部１６２ｃ，１６２ｄにおいて非水電解液のＬｉイオン濃度（Ｌｉ塩濃度）が大きく低下することを防止できる。さらには、発電平坦部１６２における非水電解液のＬｉイオン濃度の偏りの程度（Ｌｉイオン濃度が高い部位と低い部位との濃度差）を小さくすることができる。これにより、リチウムイオン二次電池１００の内部抵抗の上昇を抑制することができると考えられる。 Therefore, it is possible to prevent the Li ion concentration (Li salt concentration) of the non-aqueous electrolyte from greatly decreasing at both axial ends 162c and 162d of the power generation flat portion 162. Furthermore, the degree of unevenness of the Li ion concentration of the non-aqueous electrolyte in the power generation flat portion 162 (concentration difference between the portion where the Li ion concentration is high and the portion where the Li ion concentration is low) can be reduced. Thereby, it is considered that an increase in internal resistance of the lithium ion secondary battery 100 can be suppressed.
　なお、比較形態のリチウムイオン二次電池でも、上端側発電弧状部から流れ落ちてきた非水電解液によって、発電平坦部の軸線方向両端部（Ｌｉイオンが減少してゆく部位）に、Ｌｉイオンが供給される。しかしながら、比較形態のリチウムイオン二次電池では、上端側発電弧状部の非水電解液のＬｉ塩濃度は、発電平坦部の非水電解液のＬｉ塩濃度と等しいため、実施形態のリチウムイオン二次電池１００に比べて、上端側発電弧状部から流れ落ちてきた非水電解液による発電平坦部へのＬｉイオンの供給量はかなり少なくなる。このため、図６に示すように、比較形態のリチウムイオン二次電池では、実施形態のリチウムイオン二次電池１００に比べて、内部抵抗がかなり大きくなったと考えられる。 Even in the lithium ion secondary battery of the comparative form, Li ions are generated at both ends in the axial direction of the power generation flat portion (sites where Li ions decrease) due to the non-aqueous electrolyte flowing down from the upper end side power generation arc-shaped portion. Supplied. However, in the lithium ion secondary battery of the comparative embodiment, the Li salt concentration of the non-aqueous electrolyte in the upper-end power generation arc-shaped portion is equal to the Li salt concentration of the non-aqueous electrolyte in the power generation flat portion. Compared to the secondary battery 100, the amount of Li ions supplied to the power generation flat portion by the non-aqueous electrolyte flowing down from the upper end side power generation arc portion is considerably reduced. Therefore, as shown in FIG. 6, it is considered that the internal resistance of the comparative lithium ion secondary battery is considerably larger than that of the lithium ion secondary battery 100 of the embodiment.
　次に、リチウムイオン二次電池１００の製造方法について説明する。
　まず、図７に示すように、帯状の正極集電部材１５１の表面に正極合剤１５２が塗工された正極板１５５を用意する。さらに、図８に示すように、帯状の負極集電部材１５８の表面に負極合剤１５９が塗工された負極板１５６を用意する。 Next, a method for manufacturing the lithium ion secondary battery 100 will be described.
First, as shown in FIG. 7, a positive electrode plate 155 in which a positive electrode mixture 152 is coated on the surface of a strip-shaped positive electrode current collecting member 151 is prepared. Further, as shown in FIG. 8, a negative electrode plate 156 in which a negative electrode mixture 159 is coated on the surface of a strip-shaped negative electrode current collecting member 158 is prepared.
　次に、図９に示すように、負極板１５６、セパレータ１５７、正極板１５５、及びセパレータ１５７を、この順に積層する。具体的には、正極板１５５の正極活物質未塗工部１５５ｂと負極板１５６の負極活物質未塗工部１５６ｂが、幅方向（図９において左右方向）で互いに背向する向きで、正極活物質未塗工部１５５ｂがセパレータ１５７及び負極板１５６と重なり合わないように、且つ、負極活物質未塗工部１５６ｂがセパレータ１５７及び正極板１５５と重なり合わないように積層する。その後、積層した負極板１５６、セパレータ１５７、正極板１５５、及びセパレータ１５７を、扁平形状に捲回して、電極体１５０を形成する（図３参照）。 Next, as shown in FIG. 9, a negative electrode plate 156, a separator 157, a positive electrode plate 155, and a separator 157 are laminated in this order. Specifically, the positive electrode active material uncoated portion 155b of the positive electrode plate 155 and the negative electrode active material uncoated portion 156b of the negative electrode plate 156 are oriented so that they face each other in the width direction (left-right direction in FIG. 9). Stacking is performed so that the active material uncoated portion 155 b does not overlap the separator 157 and the negative electrode plate 156, and the negative electrode active material uncoated portion 156 b does not overlap the separator 157 and the positive electrode plate 155. Thereafter, the laminated negative electrode plate 156, separator 157, positive electrode plate 155, and separator 157 are wound into a flat shape to form the electrode body 150 (see FIG. 3).
　次いで、電極体１５０の正極捲回部１５０ｄと正極集電端子部材１２０の正極集電部１２２とを溶接する。また、電極体１５０の負極捲回部１５０ｃと負極集電端子部材１３０の負極集電部１３２とを溶接する。その後、正極集電端子部材１２０及び負極集電端子部材１３０が溶接された電極体１５０を、角形収容部１１１内に収容すると共に、蓋部１１２で角形収容部１１１の開口を閉塞する。次いで、蓋部１１２と角形収容部１１１とを溶接する。これにより、電池ケース１１０内に電極体１５０が収容された電極収容体１０１が完成する（図１０参照）。なお、蓋部１１２の中央には、蓋部１１２を貫通する貫通孔１１２ｂが形成されている。また、角形収容部１１１の底部１１１ｃの中央には、底部１１１ｃを貫通する貫通孔１１１ｂが形成されている。 Next, the positive electrode winding part 150 d of the electrode body 150 and the positive electrode current collector part 122 of the positive electrode current collector terminal member 120 are welded. Further, the negative electrode winding portion 150 c of the electrode body 150 and the negative electrode current collector portion 132 of the negative electrode current collector terminal member 130 are welded. Thereafter, the electrode body 150 to which the positive current collecting terminal member 120 and the negative current collecting terminal member 130 are welded is accommodated in the rectangular accommodating portion 111 and the opening of the rectangular accommodating portion 111 is closed by the lid portion 112. Next, the lid portion 112 and the square housing portion 111 are welded. Thereby, the electrode housing body 101 in which the electrode body 150 is housed in the battery case 110 is completed (see FIG. 10). A through hole 112 b that penetrates the lid 112 is formed at the center of the lid 112. In addition, a through-hole 111b that penetrates the bottom 111c is formed at the center of the bottom 111c of the rectangular accommodating portion 111.
　次に、電池ケース１１０内（詳細には、電極体１５０の発電部１６０の内部）に非水電解液を注入する。具体的には、まず、図１１に示すように、電極収容体１０１の上下の向きを反対にした状態（電極体１５０の発電部１６０について、上端側発電弧状部１６１を鉛直方向下側に、下端側発電弧状部１６３を鉛直方向上側にした状態）で、蓋部１１２の貫通孔１１２ｂを通じて、非水電解液１４０Ｂを電池ケース１１０内に注入する。なお、非水電解液１４０Ｂの注入量は、上端側発電弧状部１６１の全体に非水電解液１４０Ｂが含まれる量としている。また、非水電解液１４０ＢのＬｉ塩（ＬｉＰＦ６）の濃度は、１．２ｍｏｌ／Ｌに調整している。 Next, a non-aqueous electrolyte is injected into the battery case 110 (specifically, inside the power generation unit 160 of the electrode body 150). Specifically, first, as shown in FIG. 11, the electrode container 101 is turned upside down (the power generation portion 160 of the electrode body 150 has the upper end side power generation arc-shaped portion 161 on the lower side in the vertical direction. In a state where the lower end side power generation arc-shaped portion 163 is set to the upper side in the vertical direction), the nonaqueous electrolyte solution 140B is injected into the battery case 110 through the through hole 112b of the lid portion 112. The injection amount of the non-aqueous electrolyte 140B is set to an amount in which the non-aqueous electrolyte 140B is contained in the entire upper end side power generation arc-shaped portion 161. The concentration of Li salt in the nonaqueous electrolyte 140B (LiPF 6) is adjusted to 1.2 mol / L.
　その後、図１２に示すように、蓋部１１２の貫通孔１１２ｂを、封止部材１１４により仮封止する。次いで、真空ポンプ（図示なし）を用いて、角形収容部１１１の底部１１１ｃに形成されている貫通孔１１１ｂを通じて、電池ケース１１０内のガスＧを外部に排出し、電池ケース１１０内を減圧する（図１２参照）。なお、ここでは、真空ポンプ（図示なし）の設定圧を９０ｋＰａとして、５秒間、真空ポンプによる電池ケース１１０内の減圧を行っている。これにより、図１３にドット（ドットハッチング）で示すように、上端側発電弧状部１６１の内部に非水電解液１４０Ｂを含有させることができる。 Thereafter, as shown in FIG. 12, the through hole 112 b of the lid portion 112 is temporarily sealed with a sealing member 114. Next, using a vacuum pump (not shown), the gas G in the battery case 110 is discharged to the outside through the through hole 111b formed in the bottom 111c of the rectangular accommodating part 111, and the inside of the battery case 110 is depressurized ( (See FIG. 12). Here, the set pressure of the vacuum pump (not shown) is 90 kPa, and the pressure in the battery case 110 is reduced by the vacuum pump for 5 seconds. Thereby, as shown by a dot (dot hatching) in FIG. 13, the non-aqueous electrolyte solution 140 </ b> B can be contained in the upper end side power generation arc-shaped portion 161.
　次に、図１４に示すように、電極収容体１０１の上下の向きを元の状態に戻す（電極体１５０の発電部１６０について、上端側発電弧状部１６１を鉛直方向上側に、下端側発電弧状部１６３を鉛直方向下側にする）。この状態で、角形収容部１１１の貫通孔１１１ｂを通じて、非水電解液１４０Ｃを電池ケース１１０内に注入する。なお、非水電解液１４０Ｃの注入量は、発電平坦部１６２及び下端側発電弧状部１６３の全体に非水電解液１４０Ｃが含まれる量としている。また、非水電解液１４０ＣのＬｉ塩（ＬｉＰＦ６）の濃度は、１．０ｍｏｌ／Ｌに調整している。 Next, as shown in FIG. 14, the vertical direction of the electrode housing 101 is returned to the original state (for the power generation unit 160 of the electrode body 150, the upper end side power generation arc-shaped portion 161 is vertically upward and the lower end side power generation arc shape is The part 163 is set to the lower side in the vertical direction). In this state, the nonaqueous electrolytic solution 140C is injected into the battery case 110 through the through hole 111b of the rectangular accommodating portion 111. The injection amount of the non-aqueous electrolyte 140C is an amount in which the non-aqueous electrolyte 140C is contained in the entire power generation flat portion 162 and the lower end side power generation arc-shaped portion 163. The concentration of the non-aqueous electrolyte Li salt 140C (LiPF 6) is adjusted to 1.0 mol / L.
　次いで、図１５に示すように、角形収容部１１１の貫通孔１１１ｂを、封止部材１１３により封止する。次いで、蓋部１１２の貫通孔１１２ｂの仮封止を解放し（封止部材１１４を取り外し）、真空ポンプ（図示なし）を用いて、蓋部１１２の貫通孔１１２ｂを通じて、電池ケース１１０内のガスＧを外部に排出し、電池ケース１１０内を減圧する（図１６参照）。なお、ここでは、真空ポンプ（図示なし）の設定圧を９０ｋＰａとして、２５秒間、真空ポンプによる電池ケース１１０内の減圧を行っている。これにより、図１７にドット（ドットハッチング）で示すように、発電平坦部１６２及び下端側発電弧状部１６３の内部に非水電解液１４０Ｂを含有させることができる。
　その後、蓋部１１２の貫通孔１１２ｂを、封止部材１１４により封止する。これにより、本実施形態のリチウムイオン二次電池１００（図２参照）が完成する。 Next, as shown in FIG. 15, the through hole 111 b of the rectangular accommodating portion 111 is sealed with a sealing member 113. Next, the temporary sealing of the through hole 112b of the lid 112 is released (the sealing member 114 is removed), and the gas in the battery case 110 is passed through the through hole 112b of the lid 112 using a vacuum pump (not shown). G is discharged to the outside, and the inside of the battery case 110 is depressurized (see FIG. 16). Here, the set pressure of the vacuum pump (not shown) is set to 90 kPa, and the pressure in the battery case 110 is reduced by the vacuum pump for 25 seconds. Thereby, as shown by a dot (dot hatching) in FIG. 17, the non-aqueous electrolyte solution 140 </ b> B can be contained in the power generation flat portion 162 and the lower end side power generation arc-shaped portion 163.
Thereafter, the through hole 112 b of the lid portion 112 is sealed with the sealing member 114. Thereby, the lithium ion secondary battery 100 (refer FIG. 2) of this embodiment is completed.
　以上において、本発明を実施形態に即して説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることはいうまでもない。 As mentioned above, although this invention was demonstrated according to embodiment, it cannot be overemphasized that this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change suitably and can be applied.
１　車両（ハイブリッド自動車）
１０　組電池
１００　リチウムイオン二次電池
１１０　電池ケース
１４０Ｂ　第１非水電解液
１４０Ｃ　第２非水電解液
１５０　電極体
１６０　発電部
１６１　上端側発電弧状部
１６２　発電平坦部
１６３　下端側発電弧状部
１５５　正極板
１５５ｃ　正極活物質塗工部（正極板の活物質塗工部）
１５６　負極板
１５６ｃ　負極活物質塗工部（負極板の活物質塗工部）
１５７　セパレータ 1 Vehicle (hybrid vehicle)
10 assembled battery 100 lithium ion secondary battery 110 battery case 140B first nonaqueous electrolyte 140C second nonaqueous electrolyte 150 electrode body 160 power generation unit 161 upper end side power generation arcuate portion 162 power generation flat portion 163 lower end side power generation arcuate portion 155 positive electrode Plate 155c Positive electrode active material coating part (active material coating part of positive electrode plate)
156 Negative electrode plate 156c Negative electrode active material coating part (active material coating part of negative electrode plate)
157 Separator

Claims (4)

  1. 　正極板、負極板、及びセパレータを扁平形状に捲回した電極体であって、上記正極板の活物質塗工部と上記負極板の活物質塗工部と上記セパレータとが重なり合う発電部を有する電極体と、
    　Ｌｉ塩を含有する非水電解液であって、上記発電部に含まれる非水電解液と、を備える
    リチウムイオン二次電池において、
    　上記発電部は、当該発電部の上端部をなす上端側発電弧状部と、当該発電部の下端部をなす下端側発電弧状部と、上記上端側発電弧状部と上記下端側発電弧状部との間に位置する発電平坦部と、からなり、
    　上記上端側発電弧状部に含まれる上記非水電解液の上記Ｌｉ塩の濃度は、上記発電平坦部及び上記下端側発電弧状部に含まれる上記非水電解液の上記Ｌｉ塩の濃度よりも高くされてなる
    リチウムイオン二次電池。     An electrode body obtained by winding a positive electrode plate, a negative electrode plate, and a separator into a flat shape, and having a power generation unit in which the active material coating part of the positive electrode plate, the active material coating part of the negative electrode plate, and the separator overlap each other An electrode body;
    In a lithium ion secondary battery comprising a non-aqueous electrolyte containing a Li salt, the non-aqueous electrolyte included in the power generation unit,
    The power generation unit includes an upper end side power generation arc-shaped portion that forms an upper end portion of the power generation unit, a lower end side power generation arc-shaped portion that forms a lower end portion of the power generation unit, and the upper end side power generation arc-shaped portion and the lower end side power generation arc-shaped portion. And a power generation flat part located between,
    The concentration of the Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is higher than the concentration of the Li salt in the non-aqueous electrolyte contained in the power generation flat portion and the lower-end power generation arc-shaped portion. Lithium ion secondary battery.
  2. 請求項１に記載のリチウムイオン二次電池であって、
    　前記上端側発電弧状部に含まれる前記非水電解液の前記Ｌｉ塩の濃度は、前記発電平坦部及び前記下端側発電弧状部に含まれる前記非水電解液の前記Ｌｉ塩の濃度よりも、０．２ｍｏｌ／Ｌ以上高くされてなる
    リチウムイオン二次電池。     The lithium ion secondary battery according to claim 1,
    The concentration of the Li salt in the non-aqueous electrolyte contained in the upper-end power generation arc-shaped portion is higher than the concentration of the Li salt in the non-aqueous electrolyte contained in the power generation flat portion and the lower-end power generation arc-shaped portion. A lithium ion secondary battery made higher by 0.2 mol / L or more.
  3. 請求項１または請求項２に記載のリチウムイオン二次電池であって、
    　前記リチウムイオン二次電池は、１０Ｃ以上で充電または放電が行われる
    リチウムイオン二次電池。     The lithium ion secondary battery according to claim 1 or 2,
    The lithium ion secondary battery is a lithium ion secondary battery that is charged or discharged at 10 C or higher.
  4. 車両であって、
    　請求項１～請求項３のいずれか一項に記載のリチウムイオン二次電池を、当該車両の駆動用電源として搭載してなる
    車両。     A vehicle,
    A vehicle comprising the lithium ion secondary battery according to any one of claims 1 to 3 mounted as a driving power source for the vehicle.
PCT/JP2009/061586 2009-06-25 2009-06-25 Lithium ion secondary battery, and vehicle WO2010150377A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2009/061586 WO2010150377A1 (en) 2009-06-25 2009-06-25 Lithium ion secondary battery, and vehicle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2009/061586 WO2010150377A1 (en) 2009-06-25 2009-06-25 Lithium ion secondary battery, and vehicle

Publications (1)

Publication Number Publication Date
WO2010150377A1 true WO2010150377A1 (en) 2010-12-29

Family

ID=43386171

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2009/061586 WO2010150377A1 (en) 2009-06-25 2009-06-25 Lithium ion secondary battery, and vehicle

Country Status (1)

Country Link
WO (1) WO2010150377A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10461375B2 (en) 2017-03-17 2019-10-29 Kabushiki Kaisha Toshiba Secondary battery, battery pack, and vehicle

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003173821A (en) * 2001-09-28 2003-06-20 Tdk Corp Nonaqueous electrolyte cell
JP2005050756A (en) * 2003-07-31 2005-02-24 Nissan Motor Co Ltd Gel electrolyte battery
JP2009043546A (en) * 2007-08-08 2009-02-26 Hitachi Ltd Lithium secondary battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003173821A (en) * 2001-09-28 2003-06-20 Tdk Corp Nonaqueous electrolyte cell
JP2005050756A (en) * 2003-07-31 2005-02-24 Nissan Motor Co Ltd Gel electrolyte battery
JP2009043546A (en) * 2007-08-08 2009-02-26 Hitachi Ltd Lithium secondary battery

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10461375B2 (en) 2017-03-17 2019-10-29 Kabushiki Kaisha Toshiba Secondary battery, battery pack, and vehicle

Similar Documents

Publication Publication Date Title
JP5693902B2 (en) Nonaqueous electrolyte battery, battery pack, and automobile
US20170229743A1 (en) Nonaqueous electrolyte secondary battery
KR101763055B1 (en) Non-aqueous electrolytic secondary battery
JP6399380B2 (en) Power storage element, power storage system, and manufacturing method thereof
US20090136838A1 (en) Lithium-ion secondary battery, assembled battery, hybrid automobile, and battery system
JP2009129644A (en) Lithium ion secondary battery, battery pack, hybrid automobile, battery pack system, and charge-discharge control method
JP2011044312A (en) Nonaqueous electrolyte battery and battery pack
JP5618698B2 (en) Non-aqueous electrolyte battery
KR101707335B1 (en) Nonaqueous electrolyte secondary battery
CN108023061B (en) Secondary cell
US10101405B2 (en) Method for sorting reuseable nonaqueous electrolyte secondary battery
CN107026281B (en) Lithium ion secondary battery
JP2009037816A (en) Secondary battery and vehicle
US11721833B2 (en) Method of producing lithium ion secondary battery and negative electrode material
JP6836719B2 (en) Non-aqueous electrolyte secondary battery
JP2013084483A (en) Secondary battery and manufacturing method of the same
WO2010150377A1 (en) Lithium ion secondary battery, and vehicle
US11302905B2 (en) Negative electrode of nonaqueous lithium-ion secondary battery and nonaqueous lithium-ion secondary battery using same
JP6038560B2 (en) Non-aqueous electrolyte battery storage or transport method, battery pack storage or transport method, and non-aqueous electrolyte battery charge state maintaining method
JP2016201231A (en) Nonaqueous electrolyte secondary battery
JP6569907B2 (en) Non-aqueous electrolyte secondary battery
US9275803B2 (en) Electric storage apparatus and manufacturing method of electric storage apparatus
CN114583244B (en) Lithium ion secondary battery
WO2016035308A1 (en) Power storage device
JP2011044333A (en) Method of manufacturing lithium secondary battery

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: 09846509

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09846509

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP