WO2020021683A1 - Battery pack - Google Patents

Battery pack Download PDF

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Publication number
WO2020021683A1
WO2020021683A1 PCT/JP2018/028127 JP2018028127W WO2020021683A1 WO 2020021683 A1 WO2020021683 A1 WO 2020021683A1 JP 2018028127 W JP2018028127 W JP 2018028127W WO 2020021683 A1 WO2020021683 A1 WO 2020021683A1
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WO
WIPO (PCT)
Prior art keywords
active material
battery
cooling unit
electrode active
material layer
Prior art date
Application number
PCT/JP2018/028127
Other languages
French (fr)
Japanese (ja)
Inventor
一樹 在原
淳史 宝来
垣内　孝宏
Original Assignee
日産自動車株式会社
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 日産自動車株式会社 filed Critical 日産自動車株式会社
Priority to PCT/JP2018/028127 priority Critical patent/WO2020021683A1/en
Publication of WO2020021683A1 publication Critical patent/WO2020021683A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/61—Types of temperature control
    • H01M10/613—Cooling or keeping cold
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/64—Heating or cooling; Temperature control characterised by the shape of the cells
    • H01M10/647—Prismatic or flat cells, e.g. pouch cells
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/651—Means for temperature control structurally associated with the cells characterised by parameters specified by a numeric value or mathematical formula, e.g. ratios, sizes or concentrations
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/655—Solid structures for heat exchange or heat conduction
    • H01M10/6556—Solid parts with flow channel passages or pipes for heat exchange
    • H01M10/6557—Solid parts with flow channel passages or pipes for heat exchange arranged between the cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • 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 battery pack.
  • Patent Literature 1 discloses a structure of a battery pack that cools a battery using a cooling unit including a cooling pipe that forms a flow path of a refrigerant. Such a battery pack is configured such that the cooling pipe is brought into contact with the battery in a pressurized state in order to increase the adhesion between the cooling pipe and the battery and improve the cooling efficiency. .
  • an electrode active material layer not bound by a binder that is, formed of a non-bound material
  • a binder that is, formed of a non-bound material
  • the energy density of the battery can be improved by using the electrode arranged on the surface of the electric body.
  • the electrode active material layer is soft and easily deformed as compared with the dry electrode bound by the binder. According to the study of the present inventors, in the configuration in which the cooling pipe presses the battery as in Patent Document 1, the pressure applied to the battery is locally unevenly distributed, and the electrode active material layer may be deformed. Turned out to be. When the electrode active material layer is deformed, the contact resistance increases, the porosity changes, and the battery performance deteriorates.
  • the present invention has been made in view of the above circumstances, and has as its object to provide a battery pack capable of suppressing deformation of an electrode due to pressurization of a cooling unit.
  • a power generation element in which an electrode in which an electrode active material layer including a non-binder including an electrode active material is formed on the surface of a current collector and an electrolyte layer are laminated has flexibility.
  • a battery pack having a battery housed in an exterior body and a cooling unit.
  • the cooling unit forms an internal space for holding a refrigerant, and includes a contact surface that contacts at least a part of the surface of the battery in a pressurized direction from the stacking direction of the power generating elements. Further, the cooling unit is arranged so as to be flat along the surface direction of the contact surface and intermittently in the surface direction of the contact surface, and is recessed from a part of the flat portion toward the internal space. A plurality of recesses that define the flow path of the refrigerant in the internal space.
  • FIG. 1 is a perspective view schematically showing an overall structure of a battery pack according to one embodiment of the present invention.
  • FIG. 2 is an enlarged side view showing a portion A surrounded by a dashed line in FIG. 1.
  • FIG. 2 is a schematic cross-sectional view showing, on an enlarged scale, a part of the battery pack along the line BB in FIG. 1. It is a perspective view showing the cooling part concerning one embodiment of the present invention.
  • FIG. 5 is a perspective view in which a part of a portion C surrounded by a dashed line in FIG. 4 is cut away.
  • FIG. 6 is an enlarged partial cross-sectional view showing a portion D surrounded by a two-dot broken line in FIG. 5.
  • FIG. 5 is a perspective view in which a part of a portion C surrounded by a dashed line in FIG. 4.
  • FIG. 5 is a top view illustrating a shape of a concave portion of the cooling unit illustrated in FIG. 4.
  • FIG. 2 is a cross-sectional view illustrating the battery of FIG. 1.
  • FIG. 3 is a schematic sectional view illustrating an example of a configuration of an electrode active material layer.
  • FIG. 9 is a schematic diagram illustrating a flow of a refrigerant in a cooling unit of the battery pack according to Modification 1.
  • FIG. 11 is a cross-sectional view showing a part of a battery pack according to Modification 2 in an enlarged manner.
  • 13 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 3.
  • FIG. 15 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 4.
  • FIG. 15 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 5.
  • FIG. 5 is a top view
  • FIG. 1 is a perspective view schematically showing the overall structure of a battery pack 10 according to one embodiment of the present invention.
  • the battery pack 10 includes a plurality of stacked batteries 100, at least one cooling unit 20 that cools the batteries 100, and a pack case 30 that houses the batteries 100 and the cooling units 20.
  • the battery pack 10 has a substantially rectangular flat shape.
  • a stacking direction in which a plurality of batteries 100 are stacked is indicated by an arrow Z in the drawing
  • a longitudinal direction of the battery pack 10 is indicated by an arrow Y in the drawing
  • a lateral direction of the battery pack 10 is indicated.
  • the stacking direction of the plurality of batteries 100 matches the direction in which the cooling unit 20 is arranged with respect to the batteries 100.
  • the outer shape of the battery pack 10 is not limited to a substantially rectangular shape as shown in FIG. 1, and may be, for example, a substantially square shape having the same length in the X direction and the Y direction.
  • the pack case 30 of the present embodiment shown in FIG. 1 has an upper plate 31 and a bottom plate 32 that are arranged so as to sandwich a plurality of stacked batteries 100 and a plurality of cooling units 20.
  • the upper plate 31 and the bottom plate 32 are connected by a side plate 33 arranged on a side surface.
  • the connection method using the side plate 33 is not particularly limited, and examples thereof include mechanical fastening using bolts and nuts.
  • the top plate 31 and the bottom plate 32 are connected to each other, and press the cooling unit 20 and the battery 100 in the stacking direction. By pressing the plurality of batteries 100 and the cooling unit 20 in the stacking direction, the cooling unit 20 can be brought into close contact with the battery 100 to improve the cooling efficiency.
  • the method of pressurizing the battery 100 and the cooling unit 20 is not limited to the above-described configuration.
  • pressurization may be performed using an elastic member such as a leaf spring having elastic force.
  • the cooling unit 20 is preferably arranged between the stacked batteries 100. Thereby, the batteries 100 arranged on both sides of the cooling unit 20 can be efficiently cooled.
  • the cooling units 20 are stacked for each single battery 100, but the present invention is not limited to this configuration.
  • the cooling units 20 may be stacked for a plurality of batteries 100.
  • the battery 100 may be arranged only on one side of the cooling unit 20 and the cooling unit 20 may not be arranged between the batteries 100.
  • FIG. 3 is a schematic cross-sectional view showing an enlarged part of the battery pack 10 along the line BB in FIG.
  • the battery 100 includes a power generation element 111 in which an electrode in which an electrode active material layer including a non-binder including an electrode active material is formed on the surface of a current collector and an electrolyte layer are stacked. It is housed in a flexible exterior body 112.
  • the stacking direction of the constituent members of the power generation element 111 matches the direction in which the plurality of batteries 100 are stacked and the direction in which the cooling unit 20 is arranged for the batteries 100.
  • the direction in which the components of the power generating element 111 are stacked is also referred to as the “stacking direction of the power generating element 111”.
  • cooling unit 20 of the present embodiment forms an internal space 20A for holding refrigerant CM.
  • the cooling unit 20 is a cooling heat exchanger that cools the battery 100 by circulating a coolant CM supplied from the outside in the internal space 20A.
  • the cooling unit 20 includes a contact surface 20S that contacts at least a part of the surface 100S of the battery 100 in a pressurized state in order to improve the cooling efficiency of the battery 100.
  • the cooling unit 20 has a flat portion 21 that is flat along the surface direction of the contact surface 20S, and a plurality of concave portions 22 that are intermittently (discontinuously) arranged in the surface direction (XY directions) of the contact surface 20S. .
  • the recess 22 is recessed from a part of the flat portion 21 toward the internal space 20A, and defines a flow path for the refrigerant CM in the internal space 20A.
  • the contact surface 20S is formed by the flat surface 21S of the flat portion 21 that contacts the battery 100.
  • FIG. 4 is a perspective view showing the cooling unit 20 according to the present embodiment.
  • cooling unit 20 has a substantially rectangular parallelepiped shape.
  • the cooling unit 20 has a supply port 20i for supplying the refrigerant CM to the internal space 20A, and an outlet 20o for discharging the refrigerant CM in the internal space 20A.
  • the flow direction F of the refrigerant CM is formed in the longitudinal direction Y from the supply port 20i to the discharge port 20o.
  • the refrigerant CM discharged from the discharge port 20o is cooled by an external device (not shown) and supplied to the supply port 20i again.
  • the refrigerant CM circulates through the internal space 20A and the external device and maintains a state of being cooled to a predetermined temperature or lower.
  • the material constituting the refrigerant CM is not particularly limited, insulating oil such as silicon oil, antifreeze, or the like can be used.
  • the flow direction F of the coolant CM is not limited to the longitudinal direction Y, and may be formed in the short direction X.
  • the flow direction F of the refrigerant CM flowing through the internal space 20A of the plurality of cooling units 20 is the same direction (Y direction) as shown by an arrow F in FIG.
  • Setting the flow direction F of the refrigerant CM in the same direction in the plurality of cooling units 20 facilitates installation of a pipe or the like for supplying the refrigerant CM to the internal space 20A.
  • FIG. 5 is a perspective view showing a part C of the portion C surrounded by a dashed line in FIG.
  • FIG. 6 is an enlarged partial cross-sectional view of a portion D surrounded by a two-dot broken line in FIG.
  • the concave portion 22 is a convex portion protruding toward the internal space 20A.
  • the cooling unit 20 includes two plate-shaped cooling plates 23 and 24.
  • An internal space 20A for holding the refrigerant CM is formed between the two cooling plates 23 and 24.
  • the two cooling plates 23 and 24 are embossed plates each having a flat portion 21 and a plurality of concave portions 22.
  • the concave portions 22 of the two cooling plates 23 and 24 opposed to each other define the flow path of the refrigerant CM.
  • it is preferable that the concave portions 22 of the two adjacent cooling plates 23 and 24 are arranged so as to face each other. Thereby, the height of the flow path of the refrigerant CM in the Z direction becomes substantially equal to the total height of the two concave portions 22.
  • the outer peripheries of the two cooling plates 23 and 24 are joined by a joining portion 20w.
  • the joining method of the joining portion 20w is not particularly limited as long as the internal space 20A can be sealed, but welding, adhesion, or the like can be used.
  • the concave portions 22 of the two adjacent cooling plates 23 and 24 are not limited to the configuration in which they are arranged so as to face each other, and do not have to face each other.
  • the number of cooling plates constituting the cooling unit 20 is not limited to two, and may be three or more.
  • the cooling unit 20 is not limited to a configuration configured by a plurality of cooling plates, and may be configured by, for example, a box-shaped housing including an internal space that holds the refrigerant CM. In this case, a concave portion for partitioning and forming the coolant CM flow path can be formed on the surface of the housing.
  • the cooling unit 20 is disposed at the longitudinal end thereof in the housing 25 having an open bottom.
  • the housing 25 has a supply port 20i and a discharge port 20o.
  • the coolant CM supplied into the housing 25 from the supply port 20i flows into the internal space 20A between the cooling plates 23 and 24 via the notch 20h provided in the cooling plate 23.
  • FIG. 7 is a top view showing the shape of the recess 22 of the cooling unit 20 shown in FIG.
  • the plurality of concave portions 22 intermittently arranged in the plane direction of the flat portion 21 have a substantially circular shape having a substantially constant size, and are arranged in a staggered manner.
  • the refrigerant CM flowing in the flow direction F flows while diverging so as to avoid the plurality of recesses 22 (projections on the inner space 20A side). Thereby, since the coolant CM flows evenly to the end of the internal space 20A, the battery 100 can be uniformly cooled in the surface direction.
  • the flow path of the refrigerant CM when the flow path of the refrigerant CM is not formed in the internal space of the cooling unit by the concave portion and the entire internal space is formed as one flow path, the flow of the refrigerant CM flows in one direction in the internal space.
  • the flow becomes laminar.
  • the flow velocity of the laminar flow decreases as it approaches the wall (the surface side of the cooling unit) forming the internal space, and increases as it approaches the center of the internal space. This is because the refrigerant CM receives frictional drag from the wall. Therefore, the flow rate of the refrigerant CM varies in the internal space, and the battery 100 cannot be cooled uniformly.
  • the cross-sectional area of the flow path is large, the supply port and the discharge port of the refrigerant CM become large, so that it is difficult to prevent liquid leakage from the viewpoint of design.
  • the pressure applied to the battery 100 is locally unevenly distributed. Since the electrode of the battery 100 according to the present embodiment is formed by forming an electrode active material layer made of a non-binder that does not include a binder on the surface of the current collector, it is compared with a dry electrode bound by the binder. It is soft and easily deformed. Therefore, when the pressure applied to the battery 100 is locally unevenly distributed, the electrodes are deformed, the contact resistance is increased, and the porosity is changed, thereby lowering the battery performance.
  • the cooling unit 20 can apply a uniform surface pressure to the battery 100 by the contact surface 20S.
  • the concave portions 22 for partitioning the flow path of the refrigerant CM are intermittently arranged in the surface pressure direction, portions where the surface pressure is lost are dispersed in the surface direction. Thereby, the surface pressure distribution can be reduced and the deformation of the electrode 130 can be suppressed. Further, by reducing the surface pressure distribution and uniformly pressurizing the battery 100, the electrode reaction can be made to proceed uniformly with a constant distance between the electrodes. Thus, local deterioration of the electrode can be prevented, so that the cycle characteristics of the battery 100 can be improved.
  • the area of the contact surface 20S of the cooling unit 20 is configured to be larger than the projected area of the concave portion 22 when the stacking direction of the power generation elements 111 is set as the projection direction.
  • the lower limit of the pressing force (load applied per unit area) in the stacking direction applied from the contact surface 20S of the cooling unit 20 to the surface 100S of the battery 100 is preferably 20 kPa or more, and more than 50 kPa. Is more preferable, and 80 kPa or more is particularly preferable.
  • the upper limit of the pressing force is not particularly limited, but is preferably 500 kPa or less, more preferably 300 kPa or less, and particularly preferably 200 kPa or less. According to the study of the present inventors, the internal resistance of the battery 100 when the non-binding active material layer is used is sensitive to the applied pressure, and a much larger applied pressure than in the case of the dry electrode must be applied.
  • the internal resistance of the battery 100 did not decrease sufficiently.
  • the pressing force is large, the non-binding active material layer is easily deformed when an uneven load is applied to the battery 100.
  • the effect of the present invention that suppresses the deformation of the non-binding active material layer by equalizing the surface pressure of the contact surface 20S can be more remarkably exhibited.
  • the pressing force applied to the battery 100 in the stacking direction is not always constant in the surface direction of the contact surface 20S, and may vary depending on the surface direction.
  • a bipolar lithium ion secondary battery which is a kind of non-aqueous electrolyte secondary battery
  • the battery to which the present invention is applied is a bipolar lithium ion secondary battery.
  • a bipolar lithium ion secondary battery is a secondary battery that includes a bipolar electrode and performs charging and discharging by moving lithium ions between a positive electrode and a negative electrode.
  • the present invention can be applied to any conventionally known secondary battery such as a so-called parallel stack type battery in which electrodes are connected in parallel in a power generating element.
  • a bipolar lithium ion secondary battery is simply referred to as a “battery”.
  • FIG. 8 is a cross-sectional view schematically showing a battery 100 according to one embodiment of the present invention.
  • the battery 100 has a structure in which a power generation element 111 contributing to a charge / discharge reaction is sealed inside a flexible exterior body 112 in order to prevent external impact and environmental degradation. Having.
  • the power generation element 111 of the battery 100 of the present embodiment is a laminate in which a plurality of single cells 120 are laminated. Note that the number of laminations of the single cells 120 is preferably adjusted according to a desired voltage.
  • FIG. 8 illustrates the current collector 131 as a stacked structure (two-layer structure) in which the positive electrode current collector 131a and the negative electrode current collector 131b are combined, the current collector 131 has a single-layer structure made of a single material. You may.
  • a positive electrode current collector plate (positive tab) 134a is arranged adjacent to the positive electrode current collector 131a on the positive electrode side, and is extended and led out of the outer package 112.
  • a negative electrode current collector plate (negative electrode tab) 134b is arranged adjacent to the negative electrode current collector 131b on the negative electrode side, and is similarly extended and led out of the exterior body 112.
  • the single cell 120 includes a positive electrode 130a, a negative electrode 130b, and an electrolyte layer 140.
  • the positive electrode 130a includes a positive electrode active material layer 132a disposed on a positive electrode current collector 131a.
  • the negative electrode 130b includes a negative electrode active material layer 132b disposed on a negative electrode current collector 131b.
  • the positive electrode active material layer 132a and the negative electrode active material layer 132b are arranged so as to face each other via the electrolyte layer 140.
  • a seal part 150 is arranged on the outer periphery of the unit cell 120.
  • the seal portion 150 liquid-tightly seals the periphery of the positive electrode active material layer 132a, the negative electrode active material layer 132b, and the electrolyte layer 140 to prevent liquid junction due to leakage of the electrolyte.
  • the current collector 131 (adjacent positive electrode current collector 131a and negative electrode current collector 131b) mediates movement of electrons from one surface in contact with the positive electrode active material layer 132a to the other surface in contact with the negative electrode active material layer 132b. It has a function to do.
  • the material forming the current collector 131 is not particularly limited, and for example, a conductive resin or a metal can be used.
  • the current collector 131 is preferably a resin current collector formed of a conductive resin. From the viewpoint of blocking the movement of lithium ions between the single cells 120, a metal layer may be provided on a part of the resin current collector.
  • examples of the conductive resin that is a constituent material of the resin current collector include a resin in which a conductive filler is added as necessary to a conductive polymer material or a non-conductive polymer material.
  • examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylenevinylene, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process and reducing the weight of the current collector.
  • non-conductive polymer material examples include polyethylene (PE; high-density polyethylene (HDPE), low-density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamide imide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) , Polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or polystyrene (PS).
  • PE polyethylene
  • HDPE high-density polyethylene
  • LDPE low-density polyethylene
  • PP polypropylene
  • PET polyethylene terephthalate
  • PEN polyether nitrile
  • PI polyimide
  • PAI polyamide imide
  • PA polyamide
  • the conductive filler can be used without particular limitation as long as it is a substance having conductivity.
  • metal conductive carbon, and the like can be given.
  • the metal is not particularly limited, but is at least one metal selected from the group consisting of nickel, titanium, aluminum, copper, platinum, iron, chromium, tin, zinc, indium, antimony, and potassium, or these metals It is preferable to include an alloy or metal oxide containing Further, the conductive carbon is not particularly limited.
  • acetylene black Vulcan (registered trademark), black pearl (registered trademark), carbon nanofiber, Ketjen black (registered trademark), carbon nanotube (CNT), carbon nanohorn, carbon nanoballoon, and fullerene It is preferable to include at least one selected from them.
  • the amount of the conductive filler to be added is not particularly limited as long as it can impart sufficient conductivity to the current collector 131, and is preferably about 5 to 35% by volume.
  • the current collector 131 is formed of a metal
  • examples of the metal include aluminum, nickel, iron, stainless steel, titanium, and copper.
  • a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plated material of these metals can be preferably used.
  • a foil having a metal surface coated with aluminum may be used.
  • aluminum, stainless steel, copper, and nickel are preferable from the viewpoints of electron conductivity, battery operating potential, and adhesion of the electrode active material to the current collector 131 by sputtering.
  • FIG. 9 is a cross-sectional view illustrating an example of the electrode active material layer 132 according to this embodiment.
  • the electrode active material layer 132 (the positive electrode active material layer 132a and the negative electrode active material layer 132b) is a non-binding active material layer including a non-binding material including the electrode active material 161 (the positive electrode active material or the negative electrode active material).
  • the electrode active material layer 132 may include a coating agent 162 (a coating resin 163 and a conductive auxiliary agent 164), a conductive member 165, and the like as necessary.
  • the electrode active material layer 132 may contain an ion conductive polymer, a lithium salt, or the like, as necessary.
  • “comprising a non-binder including the electrode active material 161” means that the electrode active material 161 is in a state where its position is not fixed by a binder (also referred to as a binder). Whether the electrode active material layer 132 is made of a non-binding body of the electrode active material 161 depends on whether the electrode active material layer 132 is collapsed when the electrode active material layer 132 is completely impregnated in the electrolytic solution. Can be confirmed by observing
  • the electrode active material layer 132 made of a non-binder including the electrode active material 161
  • a step of drying a coating film made of a slurry when forming the electrode active material layer 132 is substantially not included.
  • the electrode active material layer 132 (slurry for forming the electrode active material layer 132) may be made substantially free of a binder by a technique such that the electrode active material layer 132 (a slurry for forming the electrode active material layer 132) does not contain a binder.
  • a material layer 132 can be formed.
  • the phrase that the electrode active material layer 132 (slurry for forming the electrode active material layer 132) does not substantially contain a binder specifically means that the content of the binder is 1% by mass or less (lower limit: 0%) with respect to 100% by mass of the total solid content (total amount of solid components of the members constituting the electrode active material layer 132) contained in the layer 132 (electrode active material slurry). Mass%).
  • the content of the binder is more preferably 0.5% by mass or less, further preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0% by mass. %.
  • a binder that does not substantially include the electrode active material layer 132 is a known solvent used for binding and fixing the active material particles to each other and the active material particles to the current collector 131.
  • (Dispersion medium) A dry type binder for lithium ion batteries, which includes starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, and styrene-butadiene rubber. These binders for lithium ion batteries are used by dissolving or dispersing in water or an organic solvent, and drying and solidifying by evaporating the solvent (dispersion medium) component to collect the active material particles and the active material particles. The electric body is firmly fixed.
  • the positive electrode active material examples include LiMn 2 O 4 , LiCoO 2 , LiNiO 2 , Li (Ni—Mn—Co) O 2, and lithium-based materials such as those in which some of these transition metals are replaced by other elements.
  • a transition metal composite oxide, a lithium-transition metal phosphate compound, a lithium-transition metal sulfate compound, and the like can be given.
  • two or more positive electrode active materials may be used in combination.
  • a lithium-transition metal composite oxide is used as the positive electrode active material. More preferably, a composite oxide containing lithium and nickel is used.
  • NMC composite oxide Li (Ni—Mn—Co) O 2 and those in which part of these transition metals are substituted by other elements
  • NMC composite oxide lithium-nickel-cobalt
  • An aluminum composite oxide hereinafter, also simply referred to as “NCA composite oxide” or the like is used.
  • the NMC composite oxide has a layered crystal structure in which a lithium atomic layer and a transition metal (Mn, Ni and Co are arranged in order) atomic layer are alternately stacked via an oxygen atomic layer.
  • One Li atom is contained per transition metal atom, and the amount of Li that can be extracted is twice that of the spinel-based lithium manganese oxide, that is, the supply capacity is doubled, and a high capacity can be obtained.
  • the negative electrode active material examples include carbon materials such as graphite (graphite), soft carbon, and hard carbon; lithium-transition metal composite oxides (eg, Li 4 Ti 5 O 12 ); metal materials (tin, silicon); Alloy-based negative electrode materials (eg, lithium-tin alloy, lithium-silicon alloy, lithium-aluminum alloy, lithium-aluminum-manganese alloy, and the like) and the like. In some cases, two or more negative electrode active materials may be used in combination. Preferably, from the viewpoint of capacity and output characteristics, carbon materials, lithium-transition metal composite oxides, and lithium alloy-based negative electrode materials are preferably used as the negative electrode active material.
  • a negative electrode active material other than the above may be used.
  • a coating resin such as a (meth) acrylate-based copolymer has a property of easily adhering particularly to a carbon material. Therefore, from the viewpoint of providing a structurally stable electrode material, it is preferable to use a carbon material as the negative electrode active material.
  • the conductive assistant 164 is used together with the coating resin 163 as a coating agent 162 for coating the surface of the electrode active material 161.
  • the conductive auxiliary agent 164 can contribute to improving the output characteristics of the battery at a high rate by forming an electron conductive path in the coating agent and reducing the electron transfer resistance of the electrode active material layer 132.
  • Examples of the conductive additive 164 include metals such as aluminum, stainless steel, silver, gold, copper, and titanium; alloys and metal oxides containing these metals; graphite, carbon fibers (specifically, vapor grown carbon fibers). (VGCF), carbon nanotubes (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark), furnace black, channel black, thermal lamp black, etc.). It is not limited to these. Further, a material obtained by coating the above-described metal material around a particulate ceramic material or resin material by plating or the like can also be used as the conductive assistant.
  • metals such as aluminum, stainless steel, silver, gold, copper, and titanium
  • graphite carbon fibers (specifically, vapor grown carbon fibers). (VGCF), carbon nanotubes (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark), furnace black, channel black, thermal lamp black, etc.).
  • conductive aids from the viewpoint of electrical stability, it is preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon. , Silver, gold, and carbon, and more preferably at least one carbon.
  • One of these conductive assistants may be used alone, or two or more thereof may be used in combination.
  • the shape of the conductive additive 164 is preferably in the form of particles or fibers as shown in FIG.
  • the shape of the particles is not particularly limited, and may be any shape such as a powder, a sphere, a rod, a needle, a plate, a column, an irregular shape, a scale, and a spindle. It does not matter.
  • the average particle diameter (primary particle diameter) when the conductive auxiliary is in the form of particles is preferably 100 nm or less.
  • particle diameter means the largest distance among the distances between any two points on the outline of the conductive additive.
  • the value of the “average particle diameter” is determined by using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) as an average value of the particle diameters of particles observed in several to several tens of visual fields. It is assumed that the calculated value is adopted.
  • SEM scanning electron microscope
  • TEM transmission electron microscope
  • the conductive member 165 has a function of forming an electron conduction path in the electrode active material layer 132.
  • the conductive member 165 is preferably a conductive fiber having a fibrous form.
  • carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers obtained by uniformly dispersing a highly conductive metal or graphite in synthetic fibers, and metals such as stainless steel are formed into fibers.
  • carbon fibers are preferred because they have excellent conductivity and are lightweight.
  • the constituent members of the electrode active material layer 132 the above-described electrode active material, a conductive member 165 used as needed, an ion conductive polymer, a lithium salt, and a coating agent (coating).
  • a member such as a binder that does not contribute much to the progress of the charge / discharge reaction.
  • the thickness t (the distance between the main surfaces S1 and S2 with reference to FIG. 9) of the electrode active material layer 132 is preferably 150 to 1500 ⁇ m for the positive electrode active material layer 132a. Yes, more preferably 180 to 950 ⁇ m, even more preferably 200 to 800 ⁇ m. Further, the thickness of the negative electrode active material layer 132b is preferably 150 to 1500 ⁇ m, more preferably 180 to 1200 ⁇ m, and still more preferably 200 to 1000 ⁇ m. When the thickness of the electrode active material layer 132 is equal to or greater than the above lower limit, the energy density of the battery can be sufficiently increased.
  • the thickness of the electrode active material layer 132 is equal to or less than the above upper limit, the structure of the electrode active material layer 132 can be sufficiently maintained.
  • the thickness t of the electrode active material layer 132 is not always constant in the plane direction of the main surfaces S1 and S2, and may vary depending on the plane direction.
  • the projected area of the positive electrode active material layer 132a is preferably 50 to 1500 cm 2 , more preferably 180 to 950 cm 2 , and still more preferably 200 to 800 cm 2. 2 .
  • the projected area of the negative electrode active material layer 132b is preferably from 50 to 1500 cm 2 , more preferably from 200 to 1500 cm 2 , and still more preferably from 500 to 1500 cm 2 .
  • the projected area of the electrode active material layer 132 is larger, the battery capacity can be increased, while the electrode 130 is easily deformed, so that the effect of the present invention is remarkably exhibited.
  • the ratio of the area of the contact surface 20S to the projection area of the electrode active material layer 132 is preferably 50% or more, more preferably 70% or more, and still more preferably. Is at least 80%, particularly preferably at least 90%.
  • the electrolyte used for the electrolyte layer 140 is not particularly limited, and a liquid electrolyte (electrolyte), a gel polymer electrolyte, or the like is used without any limitation. By using these electrolytes, high lithium ion conductivity can be ensured.
  • a separator may be used for the electrolyte layer 140.
  • the separator has a function of retaining electrolyte and ensuring lithium ion conductivity between the positive electrode 130a and the negative electrode 130b, and a function as a partition between the positive electrode 130a and the negative electrode 130b.
  • a separator when a liquid electrolyte (electrolyte solution) is used as the electrolyte, it is preferable to use a separator.
  • the form of the separator include a porous sheet separator and a nonwoven fabric separator made of a polymer or a fiber that absorbs and retains the electrolyte.
  • the electrolytic solution liquid electrolyte
  • the concentration of the lithium salt in the electrolyte is preferably from 0.1 to 3.0 M, more preferably from 0.8 to 2.2 M.
  • the amount of the additive is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, based on 100% by mass of the electrolyte before adding the additive. is there.
  • Examples of the additive include vinylene carbonate, methyl vinylene carbonate, dimethyl vinylene carbonate, phenyl vinylene carbonate, diphenyl vinylene carbonate, ethyl vinylene carbonate, diethyl vinylene carbonate, vinyl ethylene carbonate, 1,2-divinyl ethylene carbonate, and 1-methyl- 1-vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-1-vinylethylene carbonate, 1-ethyl-2-vinylethylene carbonate, vinylvinylene carbonate, allylethylene carbonate, vinyloxymethylethylene carbonate, Allyloxymethyl ethylene carbonate, acryloxymethyl ethylene carbonate, methacryloxymethyl Ethylene carbonate, ethynyl ethylene carbonate, propargyl carbonate, ethynyloxy methylethylene carbonate, propargyloxy ethylene carbonate, methylene carbonate, etc.
  • 1,1-dimethyl-2-methylene-ethylene carbonate vinylene carbonate, methyl vinylene carbonate and vinyl ethylene carbonate are preferred, and vinylene carbonate and vinyl ethylene carbonate are more preferred.
  • One of these cyclic carbonates may be used alone, or two or more thereof may be used in combination.
  • the gel polymer electrolyte has a configuration in which the above-mentioned electrolyte is injected into a matrix polymer (host polymer) made of an ion conductive polymer.
  • a gel polymer electrolyte as the electrolyte is excellent in that the fluidity of the electrolyte is lost and the ionic conductivity between the layers is cut off to facilitate the flow.
  • ion conductive polymer used as the matrix polymer examples include, for example, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene ( PVdF-HEP), polymethyl methacrylate (PMMA), and copolymers thereof.
  • PEO polyethylene oxide
  • PPO polypropylene oxide
  • PEG polyethylene glycol
  • PAN polyacrylonitrile
  • PVdF-HEP polyvinylidene fluoride-hexafluoropropylene
  • PMMA polymethyl methacrylate
  • the matrix polymer of the gel polymer electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure.
  • a suitable polymerization initiator is used to polymerize a polymerizable polymer for forming a polymer electrolyte (eg, PEO or PPO) by heat polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, or the like.
  • a polymerization treatment may be performed.
  • the material forming the current collectors 134a and 134b is not particularly limited, and a known highly conductive material conventionally used as a current collector for a lithium ion secondary battery can be used.
  • a metal material such as aluminum, copper, titanium, nickel, stainless steel, or an alloy thereof is preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable. Note that the same material may be used for the positive electrode current collector 134a and the negative material may be used for the negative electrode current collector 134b.
  • the seal portion 150 has a function of preventing contact between the current collectors 131 and a short circuit at an end of the unit cell 120.
  • the material forming the seal portion 150 may be any material that has insulation properties, seal properties (liquid tightness), heat resistance at the battery operating temperature, and the like.
  • acrylic resin, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber (ethylene-propylene-diene rubber: EPDM) and the like can be used.
  • an isocyanate-based adhesive, an acrylic resin-based adhesive, a cyanoacrylate-based adhesive, or the like, or a hot melt adhesive (urethane resin, polyamide resin, polyolefin resin), or the like may be used.
  • polyethylene resin or polypropylene resin is preferably used as a constituent material of the insulating layer from the viewpoint of corrosion resistance, chemical resistance, ease of production (film forming property), economy, etc.
  • non-crystalline polypropylene resin is a main component. It is preferable to use a resin obtained by copolymerizing ethylene, propylene, and butene.
  • the exterior body 112 is made of a flexible sheet material.
  • the sheet material having flexibility is not particularly limited, but is composed of a laminate film from the viewpoint that it is excellent in high output and cooling performance and can be suitably used for batteries for large-sized devices for EV and HEV. Is preferred.
  • the laminate film for example, a laminate film having a three-layer structure in which polypropylene (PP), aluminum, and nylon are laminated in this order can be used, but the laminate film is not limited thereto.
  • the exterior body 112 is more preferably made of an alumina laminate.
  • the battery pack 10 includes the battery 100 and the cooling unit 20.
  • the battery 100 includes a power generation element 111 having an electrode 130 in which an electrode active material layer 132 made of a non-binder including an electrode active material 161 is formed on the surface of a current collector 131. It is housed in the body 112.
  • the cooling unit 20 has an internal space 20A that holds the refrigerant CM, and includes a contact surface 20S that contacts at least a part of the surface 100S of the battery 100 in a pressurized direction from the stacking direction of the power generation element 11.
  • the cooling unit 20 is disposed intermittently in the plane direction of the contact surface 20S and the flat portion 21 flat along the surface direction of the contact surface 20S, and is recessed from a part of the flat portion 21 toward the internal space 20A side, A plurality of recesses 22 that define the flow path of the refrigerant CM in the internal space 20A.
  • the contact surface 20S of the cooling unit 20 can apply a uniform surface pressure to the battery 100. Further, since the concave portions 22 for partitioning the flow path of the refrigerant CM are intermittently (discontinuously) arranged in the surface pressure direction, portions where the surface pressure is released are dispersed in the surface direction. Thereby, the surface pressure distribution can be reduced and the deformation of the electrode 130 can be suppressed.
  • the area of the contact surface 20S of the cooling unit 20 is configured to be larger than the projection area of the concave portion 22 when the stacking direction of the power generation elements 11 is the projection direction. Accordingly, the area of the contact surface 20S for applying a uniform surface pressure can be increased as compared with the projection area of the concave portion 22 where the surface pressure is released, so that the surface pressure distribution is reduced and the deformation of the electrode 130 is suppressed. The effect of this is remarkable.
  • the cooling unit 20 includes a plurality of cooling plates 23 and 24 having a flat portion 21 and a plurality of concave portions 22.
  • An internal space 20A is formed between the adjacent cooling plates 23 and 24.
  • the ratio of the area of the contact surface 20S to the projection area of the electrode active material layer 132 is preferably 50% or more.
  • the pressure applied to battery 100 from contact surface 20S is preferably 20 kPa or more.
  • the internal resistance of the battery 100 when the non-binding active material layer is used is sensitive to the pressing force, and the internal resistance of the battery 100 does not sufficiently decrease unless a larger pressing force is applied than in the case of the dry electrode. .
  • the pressing force is large, the non-binding active material layer is easily deformed when an uneven load is applied to the battery 100. For this reason, the effect of the present invention that suppresses the deformation of the non-binding active material layer by equalizing the surface pressure of the contact surface 20S can be more remarkably exhibited.
  • the present invention is not limited to the contents described in the above-described embodiment, but can be appropriately changed based on the description in the claims.
  • an example of the modified example will be described.
  • symbol is attached
  • FIG. 10 is a schematic diagram illustrating the flow of the refrigerant in the cooling unit of the battery pack according to the first modification.
  • the plurality of cooling units 20 are described as allowing the coolant CM to flow in the same direction (Y direction).
  • the flow direction F of the refrigerant CM may be different between them. Since the coolant CM absorbs heat to cool the battery 100, the temperature increases from the supply port 20i to the discharge port 20o. Therefore, by making the flow direction of the refrigerant CM different between the cooling units 20 as shown in FIG. 10, the temperature difference in the flow direction F of the refrigerant CM in the entire battery pack can be reduced.
  • FIG. 11 is a cross-sectional view illustrating a part of a battery pack according to Modification Example 2 in an enlarged manner.
  • the cooling unit 220 of the battery pack according to Modification 2 is different from the above-described embodiment in that the cooling unit 220 further includes a surface pressure distribution plate 26 disposed between the battery 100 and the flat portion 21.
  • the contact surface 20S contacts the battery 100 of the surface 26S of the surface pressure distribution plate 26 facing the battery 100. It is constituted by the surface to do.
  • the surface pressure distribution plate 26 is configured by a flat plate.
  • the surface pressure distribution plate 26 is cooled by surface contact with the flat surface 21S of the flat portion 21 cooled by the refrigerant CM.
  • the cooled surface pressure distribution plate 26 cools the battery 100 via the contact surface 20S.
  • the constituent material of the surface pressure dispersion plate 26 is not particularly limited as long as it is a material having high thermal conductivity to the extent that the heat of the battery 100 can be transmitted to the coolant CM.
  • a metal material such as copper or aluminum can be used.
  • the thickness of the surface pressure dispersion plate 26 in the stacking direction is not particularly limited as long as it is thin enough to transmit the heat of the battery 100 to the refrigerant CM, but is preferably 0.1 to 10 mm, more preferably 0.2 to 10 mm. 5 mm, more preferably 0.5 to 3 mm.
  • the battery 100 receives the surface pressure from the flat surface 21S of the flat portion 21. Therefore, when the concave portions in which the surface pressure is released are continuously arranged in the surface direction, the surface pressure applied to the electrode 130 of the battery 100 may be locally localized and the electrode 130 may be deformed. Therefore, also in Modification Example 2, the concave portions 22 are intermittently arranged in the plane direction as in the embodiment of the present invention, thereby exhibiting an effect of reducing the surface pressure distribution and suppressing the deformation of the electrode 130.
  • FIG. 12 is a top view illustrating the shape of the concave portion 322 of the cooling unit according to the third modification.
  • the concave portion 322 of the cooling unit according to Modification 3 is formed such that the projected area decreases toward the flow direction F of the coolant CM when the stacking direction is the projection direction.
  • the cross-sectional area of the flow path of the refrigerant CM defined by the recess 322 increases in the flow direction F of the refrigerant CM.
  • the pressure loss in the flow path decreases in the flow direction F of the refrigerant CM, so that the refrigerant CM can be smoothly circulated, and the cooling efficiency of the cooling unit can be increased.
  • FIG. 13 is a top view illustrating the shape of the recess 422 of the cooling unit according to the fourth modification.
  • the concave portion 422 of the cooling unit according to Modification Example 4 has a tapered shape on the supply side of the coolant CM (the side opposite to the flow direction F) when viewed from the laminating direction. Accordingly, the resistance to the flow of the concave portion 422 is reduced, so that the flow of the refrigerant CM can be formed smoothly without obstructing the flow of the refrigerant CM flowing in the flow direction F.
  • FIG. 14 is a top view illustrating the shape of the recess 522 of the cooling unit according to the fifth modification.
  • the concave portion 522 of the cooling unit according to Modification Example 5 has a rectangular outer shape that extends in a long direction in the flow direction F of the coolant CM when viewed from the lamination direction. Since the flow of the refrigerant CM is guided in the direction in which the concave portion 522 extends in an elongated shape, the flow in the flow direction F can be formed more reliably.
  • the outer shape of the concave portion is not particularly limited as long as it has a shape extending in a long shape. For example, the same effect as described above can be obtained even if the concave shape is an elliptical shape.
  • 10 battery pack 11 power generation elements, 20, 220 cooling unit, 20A internal space, 20S contact surface, 20i supply port, 20o outlet, 21 flat part, 22, 322, 422, 522 recess, 23, 24 cooling plate, 25 housing, 26 surface pressure dispersion plate, 30 pack case, 100 batteries, 100S surface, 111 power generation elements, 112 exterior body, 120 single cells, 130 electrodes, 130a positive electrode, 130b negative electrode, 131 current collector, 131a positive electrode current collector, 131b negative electrode current collector, 132 electrode active material layer, 132a positive electrode active material layer, 132b negative electrode active material layer, 135 bipolar electrode, 140 electrolyte layer, 150 seal part, 161 electrode active material.

Abstract

[Problem] To provide a battery pack in which it is possible to inhibit deformation of an electrode due to compression of a cooling part. [Solution] A battery pack 10, having: batteries 100, in which power generation elements 111 obtained by stacking an electrode and an electrolyte layer are housed in a flexible exterior body 112, the electrodes being obtained by forming, on a surface of a current collector, an electrode active material layer comprising a non-bonded body that contains an electrode active material; and a cooling part 20 forming an internal space 20A for holding a coolant CM, the cooling part 20 being provided with contact surfaces 20S that contact at least a part of a surface of the batteries, in a compressed state, from the direction in which the power generation elements are stacked. The cooling part is provided with: flat parts 21, which are flat along the planar direction of the contact surfaces; and a plurality of recesses 22, which are disposed intermittently in the planar direction of the contact surfaces and which indent from portions of the flat parts towards the internal space and demarcate and form coolant channels in the internal space.

Description

電池パックBattery pack
　本発明は、電池パックに関する。 The present invention relates to a battery pack.
　発電要素が可撓性を有する外装体に収容された複数の電池を積層して構成した電池パックが知られている。このような電池パックは、充放電に伴う電池の温度上昇を抑制するための冷却構造を備える。例えば下記特許文献１には、冷媒の流路を形成する冷却用パイプを備える冷却部を用いて電池を冷却する電池パックの構造が開示されている。このような電池パックにおいては、冷却用パイプと電池との密着性を高めて冷却効率を向上させるために、冷却用パイプを電池に対して加圧させた状態で接触させるように構成されている。 電池 A battery pack in which a plurality of batteries in which a power generation element is accommodated in a flexible outer package is stacked is known. Such a battery pack is provided with a cooling structure for suppressing a temperature rise of the battery due to charging and discharging. For example, Patent Literature 1 below discloses a structure of a battery pack that cools a battery using a cooling unit including a cooling pipe that forms a flow path of a refrigerant. Such a battery pack is configured such that the cooling pipe is brought into contact with the battery in a pressurized state in order to increase the adhesion between the cooling pipe and the battery and improve the cooling efficiency. .
特許第５１４２６０５号Patent No. 5142605
　ところで、本発明者らの検討によれば、バインダによって結着されていない（すなわち、非結着体からなる）電極活物質層（以下、単に「非結着活物質層」とも称する）が集電体の表面に配置された電極を用いることによって電池のエネルギー密度を向上させることができることが判明した。 By the way, according to the study of the present inventors, an electrode active material layer not bound by a binder (that is, formed of a non-bound material) (hereinafter, also simply referred to as a “non-bound active material layer”) is collected. It has been found that the energy density of the battery can be improved by using the electrode arranged on the surface of the electric body.
　このような非結着活物質層の構成成分はバインダによって結着されていないため、バインダによって結着された乾燥電極と比較すると電極活物質層が柔らかく変形し易い。本発明者らの検討によれば、上記特許文献１のように冷却用パイプが電池を加圧するような構成では、電池にかかる加圧力が局所的に偏在化して電極活物質層が変形する可能性があることが判明した。電極活物質層が変形すると、接触抵抗が増大したり、空孔率が変化したりして、電池性能の低下を招いてしまう。 (4) Since the components of the non-binding active material layer are not bound by the binder, the electrode active material layer is soft and easily deformed as compared with the dry electrode bound by the binder. According to the study of the present inventors, in the configuration in which the cooling pipe presses the battery as in Patent Document 1, the pressure applied to the battery is locally unevenly distributed, and the electrode active material layer may be deformed. Turned out to be. When the electrode active material layer is deformed, the contact resistance increases, the porosity changes, and the battery performance deteriorates.
　そこで本発明は、上記事情に鑑みてなされたものであり、冷却部の加圧による電極の変形を抑制することができる電池パックを提供することを目的とする。 Accordingly, the present invention has been made in view of the above circumstances, and has as its object to provide a battery pack capable of suppressing deformation of an electrode due to pressurization of a cooling unit.
　本発明の一形態によれば、電極活物質を含む非結着体からなる電極活物質層が集電体の表面に形成されてなる電極と電解質層とを積層した発電要素が可撓性を有する外装体に収容された電池と、冷却部と、を有する電池パックが提供される。そして、当該冷却部は、冷媒を保持する内部空間を形成し、前記発電要素の前記積層方向から前記電池の表面の少なくとも一部に対して加圧した状態で接触する接触面を備える。さらに、前記冷却部は、前記接触面の面方向に沿って平坦な平坦部と、前記接触面の面方向に断続的に配置され、前記平坦部の一部から前記内部空間側に向かって凹み、前記内部空間に前記冷媒の流路を区画形成する複数の凹部と、を備える。 According to one embodiment of the present invention, a power generation element in which an electrode in which an electrode active material layer including a non-binder including an electrode active material is formed on the surface of a current collector and an electrolyte layer are laminated has flexibility. There is provided a battery pack having a battery housed in an exterior body and a cooling unit. The cooling unit forms an internal space for holding a refrigerant, and includes a contact surface that contacts at least a part of the surface of the battery in a pressurized direction from the stacking direction of the power generating elements. Further, the cooling unit is arranged so as to be flat along the surface direction of the contact surface and intermittently in the surface direction of the contact surface, and is recessed from a part of the flat portion toward the internal space. A plurality of recesses that define the flow path of the refrigerant in the internal space.
本発明の一実施形態に係る電池パックの全体構造の概略を示す斜視図である。FIG. 1 is a perspective view schematically showing an overall structure of a battery pack according to one embodiment of the present invention. 図１の一点破線で囲んだ部分Ａを拡大して示す側面図である。FIG. 2 is an enlarged side view showing a portion A surrounded by a dashed line in FIG. 1. 図１のＢ－Ｂ線に沿う電池パックの一部を拡大して示す概略断面図である。FIG. 2 is a schematic cross-sectional view showing, on an enlarged scale, a part of the battery pack along the line BB in FIG. 1. 本発明の一実施形態に係る冷却部を示す斜視図である。It is a perspective view showing the cooling part concerning one embodiment of the present invention. 図４の一点破線で囲んだ部分Ｃの一部を切り欠いて示す斜視図である。FIG. 5 is a perspective view in which a part of a portion C surrounded by a dashed line in FIG. 4 is cut away. 図５の二点破線で囲んだ部分Ｄを拡大して示す部分断面図である。FIG. 6 is an enlarged partial cross-sectional view showing a portion D surrounded by a two-dot broken line in FIG. 5. 図４に示す冷却部の凹部の形状を示す上面図である。FIG. 5 is a top view illustrating a shape of a concave portion of the cooling unit illustrated in FIG. 4. 図１の電池を示す断面図である。FIG. 2 is a cross-sectional view illustrating the battery of FIG. 1. 電極活物質層の構成の一例を示す概略断面図である。FIG. 3 is a schematic sectional view illustrating an example of a configuration of an electrode active material layer. 変形例１に係る電池パックの冷却部内の冷媒の流れを示す概略図である。FIG. 9 is a schematic diagram illustrating a flow of a refrigerant in a cooling unit of the battery pack according to Modification 1. 変形例２に係る電池パックの一部を拡大して示す断面図である。FIG. 11 is a cross-sectional view showing a part of a battery pack according to Modification 2 in an enlarged manner. 変形例３に係る冷却部の凹部の形状を示す上面図である。13 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 3. FIG. 変形例４に係る冷却部の凹部の形状を示す上面図である。15 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 4. FIG. 変形例５に係る冷却部の凹部の形状を示す上面図である。15 is a top view illustrating a shape of a concave portion of a cooling unit according to Modification Example 5. FIG.
　以下、図面を参照しながら、本発明の実施形態を説明するが、本発明の技術的範囲は特許請求の範囲の記載に基づいて定められるべきであり、以下の形態のみに制限されない。なお、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。本明細書において、範囲を示す「Ｘ～Ｙ」は「Ｘ以上Ｙ以下」を意味する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description of the claims, and is not limited to the following embodiments. Note that the dimensional ratios in the drawings are exaggerated for the sake of explanation, and may differ from the actual ratios. In the present specification, “X to Y” indicating a range means “X or more and Y or less”.
　＜電池パック＞
　図１は、本発明の一実施形態に係る電池パック１０の全体構造の概略を示す斜視図である。図１に示すように、電池パック１０は、積層された複数の電池１００と、電池１００を冷却する少なくとも１つの冷却部２０と、電池１００および冷却部２０を収容するパックケース３０と、を有する。図１に示す本形態では、電池パック１０は、略矩形の扁平形状を有する。本明細書では、説明の便宜上、複数の電池１００が積層される積層方向を図中に矢印Ｚで示し、電池パック１０の長手方向を図中に矢印Ｙで示し、電池パック１０の短手方向を図中に矢印Ｘで示す。複数の電池１００の積層方向は、電池１００に対して冷却部２０が配置される方向と一致する。なお、電池パック１０の外形は、図１に示すような略長方形に限定されず、例えば、Ｘ方向およびＹ方向の長さが同じの略正方形でもよい。 <Battery pack>
FIG. 1 is a perspective view schematically showing the overall structure of a battery pack 10 according to one embodiment of the present invention. As illustrated in FIG. 1, the battery pack 10 includes a plurality of stacked batteries 100, at least one cooling unit 20 that cools the batteries 100, and a pack case 30 that houses the batteries 100 and the cooling units 20. . In the embodiment shown in FIG. 1, the battery pack 10 has a substantially rectangular flat shape. In the present specification, for convenience of description, a stacking direction in which a plurality of batteries 100 are stacked is indicated by an arrow Z in the drawing, a longitudinal direction of the battery pack 10 is indicated by an arrow Y in the drawing, and a lateral direction of the battery pack 10 is indicated. Is indicated by an arrow X in the figure. The stacking direction of the plurality of batteries 100 matches the direction in which the cooling unit 20 is arranged with respect to the batteries 100. The outer shape of the battery pack 10 is not limited to a substantially rectangular shape as shown in FIG. 1, and may be, for example, a substantially square shape having the same length in the X direction and the Y direction.
　図１に示す本形態のパックケース３０は、積層された複数の電池１００および複数の冷却部２０を挟持するように配置される上板３１および底板３２を有する。上板３１および底板３２は、側面に配置された側板３３によって連結される。側板３３による連結方法は、特に限定されないが、例えばボルトやナットを用いた機械的締結などが挙げられる。上板３１および底板３２は互いに連結された状態で、冷却部２０および電池１００を積層方向に加圧する。複数の電池１００および冷却部２０を積層方向に加圧することによって、冷却部２０を電池１００に密着させて冷却効率を向上させることができる。また、電池１００を加圧することによって電極間距離を縮めることができるため、電池１００の内部抵抗を低下させることができる。なお、電池１００および冷却部２０を加圧する方法は、上記の構成に限定されず、例えば、弾性力を有する板バネ等の弾性部材を用いて加圧してもよい。 パ ッ ク The pack case 30 of the present embodiment shown in FIG. 1 has an upper plate 31 and a bottom plate 32 that are arranged so as to sandwich a plurality of stacked batteries 100 and a plurality of cooling units 20. The upper plate 31 and the bottom plate 32 are connected by a side plate 33 arranged on a side surface. The connection method using the side plate 33 is not particularly limited, and examples thereof include mechanical fastening using bolts and nuts. The top plate 31 and the bottom plate 32 are connected to each other, and press the cooling unit 20 and the battery 100 in the stacking direction. By pressing the plurality of batteries 100 and the cooling unit 20 in the stacking direction, the cooling unit 20 can be brought into close contact with the battery 100 to improve the cooling efficiency. Further, since the distance between the electrodes can be reduced by pressing the battery 100, the internal resistance of the battery 100 can be reduced. In addition, the method of pressurizing the battery 100 and the cooling unit 20 is not limited to the above-described configuration. For example, pressurization may be performed using an elastic member such as a leaf spring having elastic force.
　図２は、図１の一点破線で囲んだ部分Ａを拡大して示す側面図である。図２に示すように、冷却部２０は、積層された電池１００と電池１００との間に配置されることが好ましい。これにより、冷却部２０の両側に配置された電池１００を効率的に冷却することができる。なお、図２に示す形態では、一枚の電池１００毎に冷却部２０を積層しているがこの構成に限定されず、例えば、複数の電池１００毎に冷却部２０を積層してもよいし、冷却部２０の一方側のみに電池１００を配置して冷却部２０を電池１００間に配置しない形態としてもよい。 2 is an enlarged side view showing a portion A surrounded by a dashed line in FIG. As shown in FIG. 2, the cooling unit 20 is preferably arranged between the stacked batteries 100. Thereby, the batteries 100 arranged on both sides of the cooling unit 20 can be efficiently cooled. In the embodiment shown in FIG. 2, the cooling units 20 are stacked for each single battery 100, but the present invention is not limited to this configuration. For example, the cooling units 20 may be stacked for a plurality of batteries 100. Alternatively, the battery 100 may be arranged only on one side of the cooling unit 20 and the cooling unit 20 may not be arranged between the batteries 100.
　図３は、図１のＢ－Ｂ線に沿う電池パック１０の一部を拡大して示す概略断面図である。本発明の一形態に係る電池１００は、電極活物質を含む非結着体からなる電極活物質層が集電体の表面に形成されてなる電極と、電解質層とを積層した発電要素１１１が可撓性を有する外装体１１２に収容されてなる。発電要素１１１の構成部材の積層方向は、複数の電池１００が積層される方向、および電池１００に対して冷却部２０が配置される方向と一致する。なお、本明細書では、発電要素１１１の構成部材の積層方向のことを「発電要素１１１の積層方向」とも称する。 FIG. 3 is a schematic cross-sectional view showing an enlarged part of the battery pack 10 along the line BB in FIG. The battery 100 according to one embodiment of the present invention includes a power generation element 111 in which an electrode in which an electrode active material layer including a non-binder including an electrode active material is formed on the surface of a current collector and an electrolyte layer are stacked. It is housed in a flexible exterior body 112. The stacking direction of the constituent members of the power generation element 111 matches the direction in which the plurality of batteries 100 are stacked and the direction in which the cooling unit 20 is arranged for the batteries 100. In this specification, the direction in which the components of the power generating element 111 are stacked is also referred to as the “stacking direction of the power generating element 111”.
　図３を参照して、本形態の冷却部２０は、冷媒ＣＭを保持する内部空間２０Ａを形成する。冷却部２０は、外部から供給された冷媒ＣＭを内部空間２０Ａ内で循環させることによって電池１００を冷却する冷却用の熱交換器である。冷却部２０は、電池１００の冷却効率を向上するために、電池１００の表面１００Ｓの少なくとも一部に対して加圧した状態で接触する接触面２０Ｓを備える。冷却部２０は、接触面２０Ｓの面方向に沿って平坦な平坦部２１と、接触面２０Ｓの面方向（ＸＹ方向）に断続的（不連続）に配置された複数の凹部２２と、を有する。凹部２２は、平坦部２１の一部から内部空間２０Ａ側に向かって凹み、内部空間２０Ａに冷媒ＣＭの流路を区画形成する。図３に示す本形態では、平坦部２１が電池１００の表面１００Ｓに直接的に接触するため、接触面２０Ｓは平坦部２１の平坦面２１Ｓのうち電池１００に接触する面によって構成される。 冷却 Referring to FIG. 3, cooling unit 20 of the present embodiment forms an internal space 20A for holding refrigerant CM. The cooling unit 20 is a cooling heat exchanger that cools the battery 100 by circulating a coolant CM supplied from the outside in the internal space 20A. The cooling unit 20 includes a contact surface 20S that contacts at least a part of the surface 100S of the battery 100 in a pressurized state in order to improve the cooling efficiency of the battery 100. The cooling unit 20 has a flat portion 21 that is flat along the surface direction of the contact surface 20S, and a plurality of concave portions 22 that are intermittently (discontinuously) arranged in the surface direction (XY directions) of the contact surface 20S. . The recess 22 is recessed from a part of the flat portion 21 toward the internal space 20A, and defines a flow path for the refrigerant CM in the internal space 20A. In the embodiment shown in FIG. 3, since the flat portion 21 directly contacts the surface 100S of the battery 100, the contact surface 20S is formed by the flat surface 21S of the flat portion 21 that contacts the battery 100.
　図４は、本形態に係る冷却部２０を示す斜視図である。図４を参照して、冷却部２０は、略直方体の形状を有する。冷却部２０は、冷媒ＣＭを内部空間２０Ａへ供給するための供給口２０ｉと、内部空間２０Ａ内の冷媒ＣＭを排出する排出口２０ｏと、を有する。冷媒ＣＭの流れ方向Ｆは、供給口２０ｉから排出口２０ｏに向かって長手方向Ｙに形成される。排出口２０ｏから排出された冷媒ＣＭは、図示しない外部装置によって冷却されて再び供給口２０ｉへ供給される。このようにして、冷媒ＣＭは、内部空間２０Ａおよび外部装置を循環して所定温度以下に冷却された状態を維持する。冷媒ＣＭを構成する材料は、特に限定されないがシリコンオイル等の絶縁油や不凍液などを用いることができる。なお、冷媒ＣＭの流れ方向Ｆは、長手方向Ｙに限定されず、短手方向Ｘに形成してもよい。 FIG. 4 is a perspective view showing the cooling unit 20 according to the present embodiment. Referring to FIG. 4, cooling unit 20 has a substantially rectangular parallelepiped shape. The cooling unit 20 has a supply port 20i for supplying the refrigerant CM to the internal space 20A, and an outlet 20o for discharging the refrigerant CM in the internal space 20A. The flow direction F of the refrigerant CM is formed in the longitudinal direction Y from the supply port 20i to the discharge port 20o. The refrigerant CM discharged from the discharge port 20o is cooled by an external device (not shown) and supplied to the supply port 20i again. In this way, the refrigerant CM circulates through the internal space 20A and the external device and maintains a state of being cooled to a predetermined temperature or lower. Although the material constituting the refrigerant CM is not particularly limited, insulating oil such as silicon oil, antifreeze, or the like can be used. The flow direction F of the coolant CM is not limited to the longitudinal direction Y, and may be formed in the short direction X.
　図２に示す本形態では、複数の冷却部２０の内部空間２０Ａを流れる冷媒ＣＭの流れ方向Ｆは、図２中に矢印Ｆで示すように同じ方向（Ｙ方向）である。冷媒ＣＭの流れ方向Ｆを複数の冷却部２０で同じ方向とすることにより、冷媒ＣＭを内部空間２０Ａへ供給するための配管等の設置が容易となる。 In the present embodiment shown in FIG. 2, the flow direction F of the refrigerant CM flowing through the internal space 20A of the plurality of cooling units 20 is the same direction (Y direction) as shown by an arrow F in FIG. Setting the flow direction F of the refrigerant CM in the same direction in the plurality of cooling units 20 facilitates installation of a pipe or the like for supplying the refrigerant CM to the internal space 20A.
　図５は、図４の一点破線で囲んだ部分Ｃの一部を切り欠いて示す斜視図である。図６は、図５の二点破線で囲んだ部分Ｄを拡大して示す部分断面図である。図３および図６に示すように、凹部２２は、内部空間２０Ａ側に突出した凸部である。 FIG. 5 is a perspective view showing a part C of the portion C surrounded by a dashed line in FIG. FIG. 6 is an enlarged partial cross-sectional view of a portion D surrounded by a two-dot broken line in FIG. As shown in FIGS. 3 and 6, the concave portion 22 is a convex portion protruding toward the internal space 20A.
　図３、図５および図６に示す本形態では、冷却部２０は、２枚の板状の冷却板２３、２４を備える。２枚の冷却板２３、２４間には、冷媒ＣＭを保持する内部空間２０Ａが形成される。２枚の冷却板２３、２４は、それぞれ平坦部２１および複数の凹部２２を備えるエンボス加工が施された板である。互いに対向する２枚の冷却板２３、２４の凹部２２が冷媒ＣＭの流路を区画形成する。図６に示すように、隣り合う２枚の冷却板２３、２４の凹部２２は、互いに対向するように配置されることが好ましい。これにより、冷媒ＣＭの流路のＺ方向の高さは、２つの凹部２２の合計の高さにほぼ等しくなる。図５を参照して、２枚の冷却板２３、２４は、接合部２０ｗによって外周が接合されている。接合部２０ｗの接合方法は、内部空間２０Ａを密封できる限りにおいて特に限定されないが、溶接や接着等を用いることができる。 冷却 In the present embodiment shown in FIGS. 3, 5, and 6, the cooling unit 20 includes two plate-shaped cooling plates 23 and 24. An internal space 20A for holding the refrigerant CM is formed between the two cooling plates 23 and 24. The two cooling plates 23 and 24 are embossed plates each having a flat portion 21 and a plurality of concave portions 22. The concave portions 22 of the two cooling plates 23 and 24 opposed to each other define the flow path of the refrigerant CM. As shown in FIG. 6, it is preferable that the concave portions 22 of the two adjacent cooling plates 23 and 24 are arranged so as to face each other. Thereby, the height of the flow path of the refrigerant CM in the Z direction becomes substantially equal to the total height of the two concave portions 22. Referring to FIG. 5, the outer peripheries of the two cooling plates 23 and 24 are joined by a joining portion 20w. The joining method of the joining portion 20w is not particularly limited as long as the internal space 20A can be sealed, but welding, adhesion, or the like can be used.
　なお、隣り合う２枚の冷却板２３、２４の凹部２２は、互いに対向するように配置される構成に限定されず、対向してなくてもよい。また、冷却部２０を構成する冷却板の数は、２枚に限定されず、３枚以上としてもよい。さらに、冷却部２０は、複数の冷却板によって構成される形態に限定されず、例えば、冷媒ＣＭを保持する内部空間を備える箱型の筐体によって構成してもよい。この場合、筐体の表面に冷媒ＣＭ流路を区画形成するための凹部を形成することができる。 凹 部 In addition, the concave portions 22 of the two adjacent cooling plates 23 and 24 are not limited to the configuration in which they are arranged so as to face each other, and do not have to face each other. Further, the number of cooling plates constituting the cooling unit 20 is not limited to two, and may be three or more. Furthermore, the cooling unit 20 is not limited to a configuration configured by a plurality of cooling plates, and may be configured by, for example, a box-shaped housing including an internal space that holds the refrigerant CM. In this case, a concave portion for partitioning and forming the coolant CM flow path can be formed on the surface of the housing.
　図４および図５に示す本形態では、冷却部２０の長手方向の端部には、下方が開口した筐体２５に配置される。筐体２５には、供給口２０ｉおよび排出口２０ｏが形成される。供給口２０ｉから筐体２５内へ供給された冷媒ＣＭは、冷却板２３に設けられた切り欠き２０ｈを介して冷却板２３、２４の間の内部空間２０Ａへ流入する。 お よ び In the present embodiment shown in FIGS. 4 and 5, the cooling unit 20 is disposed at the longitudinal end thereof in the housing 25 having an open bottom. The housing 25 has a supply port 20i and a discharge port 20o. The coolant CM supplied into the housing 25 from the supply port 20i flows into the internal space 20A between the cooling plates 23 and 24 via the notch 20h provided in the cooling plate 23.
　図７は、図４に示す冷却部２０の凹部２２の形状を示す上面図である。平坦部２１の面方向に断続的に配置される複数の凹部２２は、大きさがほぼ一定の略円形状を有し、千鳥状に配置される。流れ方向Ｆに向かって流れる冷媒ＣＭは、複数の凹部２２（内部空間２０Ａ側の凸部）を避けるように分流しながら流れる。これにより、冷媒ＣＭは、内部空間２０Ａの端部まで均一に流れるため、電池１００を面方向に均一に冷却することができる。 FIG. 7 is a top view showing the shape of the recess 22 of the cooling unit 20 shown in FIG. The plurality of concave portions 22 intermittently arranged in the plane direction of the flat portion 21 have a substantially circular shape having a substantially constant size, and are arranged in a staggered manner. The refrigerant CM flowing in the flow direction F flows while diverging so as to avoid the plurality of recesses 22 (projections on the inner space 20A side). Thereby, since the coolant CM flows evenly to the end of the internal space 20A, the battery 100 can be uniformly cooled in the surface direction.
　本形態と異なり、冷却部の内部空間内に冷媒ＣＭの流路を凹部によって区画形成せずに、内部空間全体を一つの流路とした場合、冷媒ＣＭの流れは、内部空間内を一方向に流れる層流となる。層流は、内部空間を形成する壁部（冷却部の表面側）に近づくほど流速が小さくなり、内部空間の中心に近づくほど流速が大きくなる。これは冷媒ＣＭが壁部から摩擦抗力を受けるからである。このため、内部空間内で冷媒ＣＭの流速にばらつきが生じて、電池１００を均一に冷却することができなくなる。また、流路の断面積が大きいと冷媒ＣＭの供給口や排出口が大きくなるため、設計性の観点から液漏れを防止することが困難となる。 Unlike this embodiment, when the flow path of the refrigerant CM is not formed in the internal space of the cooling unit by the concave portion and the entire internal space is formed as one flow path, the flow of the refrigerant CM flows in one direction in the internal space. The flow becomes laminar. The flow velocity of the laminar flow decreases as it approaches the wall (the surface side of the cooling unit) forming the internal space, and increases as it approaches the center of the internal space. This is because the refrigerant CM receives frictional drag from the wall. Therefore, the flow rate of the refrigerant CM varies in the internal space, and the battery 100 cannot be cooled uniformly. In addition, if the cross-sectional area of the flow path is large, the supply port and the discharge port of the refrigerant CM become large, so that it is difficult to prevent liquid leakage from the viewpoint of design.
　一方で、流路の断面積を小さくして冷媒ＣＭの流速のばらつきを低減し、設計を容易にするため、細い管状の冷却用パイプによって冷媒ＣＭの流路を形成した場合、冷却用パイプから電池１００にかかる加圧力が局所的に偏在化してしまう。本形態に係る電池１００の電極は、バインダを含まない非結着体からなる電極活物質層が集電体の表面に形成されて構成されるため、バインダによって結着された乾燥電極と比較すると柔らかく変形し易い。このため、電池１００にかかる加圧力が局所的に偏在化すると、電極が変形して接触抵抗が増大したり、空孔率が変化したりして、電池性能の低下を招いてしまう。 On the other hand, in order to reduce the variation in the flow rate of the refrigerant CM by reducing the cross-sectional area of the flow path and to facilitate the design, when the flow path of the refrigerant CM is formed by a thin tubular cooling pipe, The pressure applied to the battery 100 is locally unevenly distributed. Since the electrode of the battery 100 according to the present embodiment is formed by forming an electrode active material layer made of a non-binder that does not include a binder on the surface of the current collector, it is compared with a dry electrode bound by the binder. It is soft and easily deformed. Therefore, when the pressure applied to the battery 100 is locally unevenly distributed, the electrodes are deformed, the contact resistance is increased, and the porosity is changed, thereby lowering the battery performance.
　冷却部から電池にかかる面圧を均一にするために、冷却部に冷却用パイプの凸部を埋めるスペーサ等を設けて表面を平らにすることも考えられる。しかしながら、冷却部の表面に冷却に寄与しない部材を配置すると、電池１００を均一に冷却できなくなり冷却効率が低下する可能性がある。 In order to make the surface pressure applied to the battery from the cooling unit uniform, it is conceivable to provide a spacer or the like for filling the convex part of the cooling pipe in the cooling unit to make the surface flat. However, if a member that does not contribute to cooling is arranged on the surface of the cooling unit, the battery 100 cannot be cooled uniformly, and the cooling efficiency may be reduced.
　これに対して、本形態に係る冷却部２０は、接触面２０Ｓによって電池１００に対して均等な面圧を付与できる。また、冷媒ＣＭの流路を区画形成するための凹部２２が面圧方向に断続的に配置されているため、面圧の抜けが生じる部分が面方向に分散する。これにより、面圧分布を低減して電極１３０の変形を抑制することができる。さらに、面圧分布を低減して電池１００を均一に加圧することによって、電極間距離を一定にして電極反応を均一に進行させることができる。これにより、電極の局所的な劣化も防止することができることから、電池１００のサイクル特性を向上させることも可能となる。 In contrast, the cooling unit 20 according to the present embodiment can apply a uniform surface pressure to the battery 100 by the contact surface 20S. Further, since the concave portions 22 for partitioning the flow path of the refrigerant CM are intermittently arranged in the surface pressure direction, portions where the surface pressure is lost are dispersed in the surface direction. Thereby, the surface pressure distribution can be reduced and the deformation of the electrode 130 can be suppressed. Further, by reducing the surface pressure distribution and uniformly pressurizing the battery 100, the electrode reaction can be made to proceed uniformly with a constant distance between the electrodes. Thus, local deterioration of the electrode can be prevented, so that the cycle characteristics of the battery 100 can be improved.
　また、冷却部２０の接触面２０Ｓの面積は、発電要素１１１の積層方向を投影方向としたときの凹部２２の投影面積よりも大きくなるように構成されている。面圧抜けが生じる凹部２２の投影面積に比べて、均等な面圧を付与する接触面２０Ｓの面積を大きくすることによって、面圧分布を低減して電極１３０の変形を抑制する効果が顕著となる。 The area of the contact surface 20S of the cooling unit 20 is configured to be larger than the projected area of the concave portion 22 when the stacking direction of the power generation elements 111 is set as the projection direction. The effect of suppressing the deformation of the electrode 130 by reducing the surface pressure distribution by increasing the area of the contact surface 20S that applies a uniform surface pressure as compared with the projection area of the concave portion 22 where the surface pressure is released is remarkable. Become.
　冷却部２０の接触面２０Ｓから電池１００の表面１００Ｓに付与される積層方向の加圧力（単位面積当たりに付与される荷重）の下限値は、２０ｋＰａ以上であることが好ましく、５０ｋＰａ以上であることがより好ましく、８０ｋＰａ以上であることが特に好ましい。また、加圧力の上限値については特に制限はないが、５００ｋＰａ以下であることが好ましく、３００ｋＰａ以下であることがより好ましく、２００ｋＰａ以下であることが特に好ましい。本発明者らの検討によれば、非結着活物質層を用いた場合の電池１００の内部抵抗は加圧力に対して感度があり、乾燥電極の場合よりもずっと大きい加圧力を印加しなければ電池１００の内部抵抗が十分に低下しないことが判明した。また、加圧力が大きい場合、電池１００対して偏荷重がかかった際に、非結着活物質層が変形しやすくなる。このため、接触面２０Ｓの面圧を均等にして非結着活物質層の変形を抑制する本発明の作用効果をより一層顕著に発現させることができる。なお、電池１００に付与される積層方向の加圧力は、接触面２０Ｓの面方向において常に一定であるとは限らず、面方向によってばらついていることもある。 The lower limit of the pressing force (load applied per unit area) in the stacking direction applied from the contact surface 20S of the cooling unit 20 to the surface 100S of the battery 100 is preferably 20 kPa or more, and more than 50 kPa. Is more preferable, and 80 kPa or more is particularly preferable. The upper limit of the pressing force is not particularly limited, but is preferably 500 kPa or less, more preferably 300 kPa or less, and particularly preferably 200 kPa or less. According to the study of the present inventors, the internal resistance of the battery 100 when the non-binding active material layer is used is sensitive to the applied pressure, and a much larger applied pressure than in the case of the dry electrode must be applied. For example, it was found that the internal resistance of the battery 100 did not decrease sufficiently. When the pressing force is large, the non-binding active material layer is easily deformed when an uneven load is applied to the battery 100. For this reason, the effect of the present invention that suppresses the deformation of the non-binding active material layer by equalizing the surface pressure of the contact surface 20S can be more remarkably exhibited. The pressing force applied to the battery 100 in the stacking direction is not always constant in the surface direction of the contact surface 20S, and may vary depending on the surface direction.
　以下、本発明の一実施形態に係る電池１００の構成について詳細に説明する。 Hereinafter, the configuration of the battery 100 according to one embodiment of the present invention will be described in detail.
　［電池］
　本発明の実施形態に係る電池１００の一例として非水電解質二次電池の１種である双極型リチウムイオン二次電池について説明するが、本発明を適用する電池は双極型リチウムイオン二次電池に制限されない。ここで、双極型リチウムイオン二次電池とは、双極型電極を含み、正極と負極との間をリチウムイオンが移動することで充電や放電を行う二次電池である。例えば、本発明は、発電要素において電極が並列接続されてなる形式のいわゆる並列積層型電池などの従来公知の任意の二次電池にも適用可能である。なお、本明細書では、双極型リチウムイオン二次電池を単に「電池」と称する。 [battery]
As an example of the battery 100 according to the embodiment of the present invention, a bipolar lithium ion secondary battery which is a kind of non-aqueous electrolyte secondary battery will be described. However, the battery to which the present invention is applied is a bipolar lithium ion secondary battery. Not restricted. Here, a bipolar lithium ion secondary battery is a secondary battery that includes a bipolar electrode and performs charging and discharging by moving lithium ions between a positive electrode and a negative electrode. For example, the present invention can be applied to any conventionally known secondary battery such as a so-called parallel stack type battery in which electrodes are connected in parallel in a power generating element. In this specification, a bipolar lithium ion secondary battery is simply referred to as a “battery”.
　図８は、本発明の一実施形態に係る電池１００を模式的に表した断面図である。電池１００は、外部からの衝撃や環境劣化を防止するために、図８に示すように、充放電反応に寄与する発電要素１１１が可撓性を有する外装体１１２の内部に封止された構造を有する。 FIG. 8 is a cross-sectional view schematically showing a battery 100 according to one embodiment of the present invention. As shown in FIG. 8, the battery 100 has a structure in which a power generation element 111 contributing to a charge / discharge reaction is sealed inside a flexible exterior body 112 in order to prevent external impact and environmental degradation. Having.
　図８に示すように、本実施形態の電池１００の発電要素１１１は、複数の単セル１２０が積層されてなる積層体である。なお、単セル１２０の積層回数は、所望する電圧に応じて調節することが好ましい。 よ う As shown in FIG. 8, the power generation element 111 of the battery 100 of the present embodiment is a laminate in which a plurality of single cells 120 are laminated. Note that the number of laminations of the single cells 120 is preferably adjusted according to a desired voltage.
　正極１３０ａおよび負極１３０ｂは、集電体１３１の一方の面に電気的に結合した正極活物質層１３２ａが形成され、集電体１３１の反対側の面に電気的に結合した負極活物質層１３２ｂが形成された双極型電極１３５を構成する。なお、図８では、集電体１３１は、正極集電体１３１ａおよび負極集電体１３１ｂを組み合わせた積層構造（２層構造）として図示しているが、単独の材料からなる単層構造であってもよい。 In the positive electrode 130a and the negative electrode 130b, a positive electrode active material layer 132a electrically connected to one surface of the current collector 131 is formed, and the negative electrode active material layer 132b electrically connected to the opposite surface of the current collector 131. Are formed on the bipolar electrode 135. Although FIG. 8 illustrates the current collector 131 as a stacked structure (two-layer structure) in which the positive electrode current collector 131a and the negative electrode current collector 131b are combined, the current collector 131 has a single-layer structure made of a single material. You may.
　さらに、図８に示す電池１００では、正極側の正極集電体１３１ａに隣接するように正極集電板（正極タブ）１３４ａが配置され、これが延長されて外装体１１２から導出している。一方、負極側の負極集電体１３１ｂに隣接するように負極集電板（負極タブ）１３４ｂが配置され、同様にこれが延長されて外装体１１２から導出している。 In addition, in the battery 100 shown in FIG. 8, a positive electrode current collector plate (positive tab) 134a is arranged adjacent to the positive electrode current collector 131a on the positive electrode side, and is extended and led out of the outer package 112. On the other hand, a negative electrode current collector plate (negative electrode tab) 134b is arranged adjacent to the negative electrode current collector 131b on the negative electrode side, and is similarly extended and led out of the exterior body 112.
　［単セル］
　図８に示すように、単セル１２０は、正極１３０ａおよび負極１３０ｂと、電解質層１４０とから構成される。正極１３０ａは、正極活物質層１３２ａが正極集電体１３１ａに配置されてなる。負極１３０ｂは、負極活物質層１３２ｂが負極集電体１３１ｂに配置されてなる。正極活物質層１３２ａと負極活物質層１３２ｂとは、電解質層１４０を介して互いに向かい合うように配置されている。 [Single cell]
As shown in FIG. 8, the single cell 120 includes a positive electrode 130a, a negative electrode 130b, and an electrolyte layer 140. The positive electrode 130a includes a positive electrode active material layer 132a disposed on a positive electrode current collector 131a. The negative electrode 130b includes a negative electrode active material layer 132b disposed on a negative electrode current collector 131b. The positive electrode active material layer 132a and the negative electrode active material layer 132b are arranged so as to face each other via the electrolyte layer 140.
　単セル１２０の外周部には、シール部１５０が配置されている。シール部１５０は、正極活物質層１３２ａ、負極活物質層１３２ｂおよび電解質層１４０の周囲を液密に封止し、電解液の漏れによる液絡を防止している。 シ ー ル A seal part 150 is arranged on the outer periphery of the unit cell 120. The seal portion 150 liquid-tightly seals the periphery of the positive electrode active material layer 132a, the negative electrode active material layer 132b, and the electrolyte layer 140 to prevent liquid junction due to leakage of the electrolyte.
　［集電体］
　集電体１３１（隣接する正極集電体１３１ａおよび負極集電体１３１ｂ）は、正極活物質層１３２ａと接する一方の面から、負極活物質層１３２ｂと接する他方の面へと電子の移動を媒介する機能を有する。集電体１３１を構成する材料は、特に限定されないが、例えば、導電性を有する樹脂や、金属が用いられうる。 [Current collector]
The current collector 131 (adjacent positive electrode current collector 131a and negative electrode current collector 131b) mediates movement of electrons from one surface in contact with the positive electrode active material layer 132a to the other surface in contact with the negative electrode active material layer 132b. It has a function to do. The material forming the current collector 131 is not particularly limited, and for example, a conductive resin or a metal can be used.
　集電体１３１の軽量化の観点からは、集電体１３１は、導電性を有する樹脂によって形成された樹脂集電体であることが好ましい。なお、単セル１２０間のリチウムイオンの移動を遮断する観点からは、樹脂集電体の一部に金属層を設けてもよい。 From the viewpoint of reducing the weight of the current collector 131, the current collector 131 is preferably a resin current collector formed of a conductive resin. From the viewpoint of blocking the movement of lithium ions between the single cells 120, a metal layer may be provided on a part of the resin current collector.
　具体的には、樹脂集電体の構成材料である導電性を有する樹脂としては、導電性高分子材料または非導電性高分子材料に必要に応じて導電性フィラーが添加された樹脂が挙げられる。導電性高分子材料としては、例えば、ポリアニリン、ポリピロール、ポリチオフェン、ポリアセチレン、ポリパラフェニレン、ポリフェニレンビニレン、およびポリオキサジアゾールなどが挙げられる。かような導電性高分子材料は、導電性フィラーを添加しなくても十分な導電性を有するため、製造工程の容易化または集電体の軽量化の点において有利である。 Specifically, examples of the conductive resin that is a constituent material of the resin current collector include a resin in which a conductive filler is added as necessary to a conductive polymer material or a non-conductive polymer material. . Examples of the conductive polymer material include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylenevinylene, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process and reducing the weight of the current collector.
　非導電性高分子材料としては、例えば、ポリエチレン（ＰＥ；高密度ポリエチレン（ＨＤＰＥ）、低密度ポリエチレン（ＬＤＰＥ）など）、ポリプロピレン（ＰＰ）、ポリエチレンテレフタレート（ＰＥＴ）、ポリエーテルニトリル（ＰＥＮ）、ポリイミド（ＰＩ）、ポリアミドイミド（ＰＡＩ）、ポリアミド（ＰＡ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、スチレン－ブタジエンゴム（ＳＢＲ）、ポリアクリロニトリル（ＰＡＮ）、ポリメチルアクリレート（ＰＭＡ）、ポリメチルメタクリレート（ＰＭＭＡ）、ポリ塩化ビニル（ＰＶＣ）、ポリフッ化ビニリデン（ＰＶｄＦ）、またはポリスチレン（ＰＳ）などが挙げられる。かような非導電性高分子材料は、優れた耐電位性または耐溶媒性を有しうる。 Examples of the non-conductive polymer material include polyethylene (PE; high-density polyethylene (HDPE), low-density polyethylene (LDPE), etc.), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamide imide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA) , Polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or polystyrene (PS). Such a non-conductive polymer material may have excellent potential resistance or solvent resistance.
　導電性フィラーは、導電性を有する物質であれば特に制限なく用いることができる。例えば、導電性、耐電位性、またはリチウムイオン遮断性に優れた材料として、金属および導電性カーボンなどが挙げられる。金属としては、特に制限はないが、ニッケル、チタン、アルミニウム、銅、白金、鉄、クロム、スズ、亜鉛、インジウム、アンチモン、およびカリウムからなる群から選択される少なくとも１種の金属もしくはこれらの金属を含む合金または金属酸化物を含むことが好ましい。また、導電性カーボンとしては、特に制限はない。好ましくは、アセチレンブラック、バルカン（登録商標）、ブラックパール（登録商標）、カーボンナノファイバー、ケッチェンブラック（登録商標）、カーボンナノチューブ（ＣＮＴ）、カーボンナノホーン、カーボンナノバルーン、およびフラーレンからなる群より選択される少なくとも１種を含むことが好ましい。 The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, as a material excellent in conductivity, potential resistance, or lithium ion blocking property, metal, conductive carbon, and the like can be given. The metal is not particularly limited, but is at least one metal selected from the group consisting of nickel, titanium, aluminum, copper, platinum, iron, chromium, tin, zinc, indium, antimony, and potassium, or these metals It is preferable to include an alloy or metal oxide containing Further, the conductive carbon is not particularly limited. Preferably, acetylene black, Vulcan (registered trademark), black pearl (registered trademark), carbon nanofiber, Ketjen black (registered trademark), carbon nanotube (CNT), carbon nanohorn, carbon nanoballoon, and fullerene It is preferable to include at least one selected from them.
　導電性フィラーの添加量は、集電体１３１に十分な導電性を付与できる量であれば特に制限はなく、好ましくは、５～３５体積％程度である。 添加 The amount of the conductive filler to be added is not particularly limited as long as it can impart sufficient conductivity to the current collector 131, and is preferably about 5 to 35% by volume.
　また、集電体１３１が金属によって形成される場合、金属としては、アルミニウム、ニッケル、鉄、ステンレス、チタン、銅などが挙げられる。これらのほか、ニッケルとアルミニウムとのクラッド材、銅とアルミニウムとのクラッド材、またはこれらの金属のめっき材などが好ましく用いられうる。また、金属表面にアルミニウムが被覆されてなる箔であってもよい。なかでも、電子伝導性や電池作動電位、集電体１３１へのスパッタリングによる電極活物質の密着性等の観点からは、アルミニウム、ステンレス、銅、ニッケルが好ましい。 When the current collector 131 is formed of a metal, examples of the metal include aluminum, nickel, iron, stainless steel, titanium, and copper. In addition, a clad material of nickel and aluminum, a clad material of copper and aluminum, or a plated material of these metals can be preferably used. Further, a foil having a metal surface coated with aluminum may be used. Among them, aluminum, stainless steel, copper, and nickel are preferable from the viewpoints of electron conductivity, battery operating potential, and adhesion of the electrode active material to the current collector 131 by sputtering.
　［電極活物質層（正極活物質層、負極活物質層）］
　図９は、本形態に係る電極活物質層１３２の一例を示す断面図である。電極活物質層１３２（正極活物質層１３２ａ、負極活物質層１３２ｂ）は、電極活物質１６１（正極活物質または負極活物質）を含む非結着体からなる非結着活物質層である。図９に示すように、電極活物質層１３２は、必要に応じて、被覆剤１６２（被覆用樹脂１６３、導電助剤１６４）、導電部材１６５等を含んでもよい。さらに、電極活物質層１３２は、必要に応じてイオン伝導性ポリマー、リチウム塩等を含んでもよい。 [Electrode active material layer (positive electrode active material layer, negative electrode active material layer)]
FIG. 9 is a cross-sectional view illustrating an example of the electrode active material layer 132 according to this embodiment. The electrode active material layer 132 (the positive electrode active material layer 132a and the negative electrode active material layer 132b) is a non-binding active material layer including a non-binding material including the electrode active material 161 (the positive electrode active material or the negative electrode active material). As shown in FIG. 9, the electrode active material layer 132 may include a coating agent 162 (a coating resin 163 and a conductive auxiliary agent 164), a conductive member 165, and the like as necessary. Further, the electrode active material layer 132 may contain an ion conductive polymer, a lithium salt, or the like, as necessary.
　ここで、「電極活物質１６１を含む非結着体からなる」とは、電極活物質１６１が結着剤（バインダともいう）により互いの位置を固定されていない状態であることを意味する。また、電極活物質層１３２が電極活物質１６１の非結着体からなるか否かは、電極活物質層１３２を電解液中に完全に含浸した場合に電極活物質層１３２が崩壊するか否かを観察することで確認できる。 Here, “comprising a non-binder including the electrode active material 161” means that the electrode active material 161 is in a state where its position is not fixed by a binder (also referred to as a binder). Whether the electrode active material layer 132 is made of a non-binding body of the electrode active material 161 depends on whether the electrode active material layer 132 is collapsed when the electrode active material layer 132 is completely impregnated in the electrolytic solution. Can be confirmed by observing
　電極活物質１６１を含む非結着体からなる電極活物質層１３２とするためには、電極活物質層１３２を形成する際にスラリーからなる塗膜を乾燥させる工程を実質的に含まないようにする、といった手法が挙げられる。また、電極活物質層１３２（電極活物質層１３２を形成するためのスラリー）が実質的に結着剤を含まないようにする、といった手法によっても活物質を含む非結着体からなる電極活物質層１３２を形成することができる。ここで、電極活物質層１３２（電極活物質層１３２を形成するためのスラリー）が実質的に結着剤を含まないとは、具体的には、結着剤の含有量が、電極活物質層１３２（電極活物質スラリー）に含まれる全固形分量（電極活物質層１３２を構成する部材のうち、固形である部材の分量の合計）１００質量％に対して、１質量％以下（下限０質量％）であることを意味する。当該結着剤の含有量は、より好ましくは０．５質量％以下であり、さらに好ましくは０．２質量％以下であり、特に好ましくは０．１質量％以下であり、最も好ましくは０質量％である。 In order to form the electrode active material layer 132 made of a non-binder including the electrode active material 161, a step of drying a coating film made of a slurry when forming the electrode active material layer 132 is substantially not included. To do it. Also, the electrode active material layer 132 (slurry for forming the electrode active material layer 132) may be made substantially free of a binder by a technique such that the electrode active material layer 132 (a slurry for forming the electrode active material layer 132) does not contain a binder. A material layer 132 can be formed. Here, the phrase that the electrode active material layer 132 (slurry for forming the electrode active material layer 132) does not substantially contain a binder specifically means that the content of the binder is 1% by mass or less (lower limit: 0%) with respect to 100% by mass of the total solid content (total amount of solid components of the members constituting the electrode active material layer 132) contained in the layer 132 (electrode active material slurry). Mass%). The content of the binder is more preferably 0.5% by mass or less, further preferably 0.2% by mass or less, particularly preferably 0.1% by mass or less, and most preferably 0% by mass. %.
　なお、本明細書において電極活物質層１３２が実質的に含まないとする結着剤とは活物質粒子同士および活物質粒子と集電体１３１とを結着固定するために用いられる公知の溶媒（分散媒）乾燥型のリチウムイオン電池用結着剤を意味し、デンプン、ポリフッ化ビニリデン、ポリビニルアルコール、カルボキシメチルセルロース、ポリビニルピロリドン、テトラフルオロエチレンおよびスチレン－ブタジエンゴムが挙げられる。これらのリチウムイオン電池用結着剤は、水又は有機溶媒に溶解又は分散して使用され、溶媒（分散媒）成分を揮発させることで乾燥、固体化して活物質粒子同士および活物質粒子と集電体とを強固に固定する。 Note that, in this specification, a binder that does not substantially include the electrode active material layer 132 is a known solvent used for binding and fixing the active material particles to each other and the active material particles to the current collector 131. (Dispersion medium) A dry type binder for lithium ion batteries, which includes starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, and styrene-butadiene rubber. These binders for lithium ion batteries are used by dissolving or dispersing in water or an organic solvent, and drying and solidifying by evaporating the solvent (dispersion medium) component to collect the active material particles and the active material particles. The electric body is firmly fixed.
　（正極活物質）
　正極活物質としては、例えば、ＬｉＭｎ２Ｏ４、ＬｉＣｏＯ２、ＬｉＮｉＯ２、Ｌｉ（Ｎｉ－Ｍｎ－Ｃｏ）Ｏ２およびこれらの遷移金属の一部が他の元素により置換されたもの等のリチウム－遷移金属複合酸化物、リチウム－遷移金属リン酸化合物、リチウム－遷移金属硫酸化合物などが挙げられる。場合によっては、２種以上の正極活物質が併用されてもよい。好ましくは、容量、出力特性の観点から、リチウム－遷移金属複合酸化物が、正極活物質として用いられる。より好ましくはリチウムとニッケルとを含有する複合酸化物が用いられる。さらに好ましくはＬｉ（Ｎｉ－Ｍｎ－Ｃｏ）Ｏ２およびこれらの遷移金属の一部が他の元素により置換されたもの（以下、単に「ＮＭＣ複合酸化物」とも称する）、またはリチウム－ニッケル－コバルト－アルミニウム複合酸化物（以下単に、「ＮＣＡ複合酸化物」とも称する）などが用いられる。ＮＭＣ複合酸化物は、リチウム原子層と遷移金属（Ｍｎ、ＮｉおよびＣｏが秩序正しく配置）原子層とが酸素原子層を介して交互に積み重なった層状結晶構造を有する。そして、遷移金属１原子あたり１個のＬｉ原子が含まれ、取り出せるＬｉ量が、スピネル系リチウムマンガン酸化物の２倍、つまり供給能力が２倍になり、高い容量を持つことができる。 (Positive electrode active material)
Examples of the positive electrode active material include LiMn 2 O 4 , LiCoO 2 , LiNiO 2 , Li (Ni—Mn—Co) O 2, and lithium-based materials such as those in which some of these transition metals are replaced by other elements. A transition metal composite oxide, a lithium-transition metal phosphate compound, a lithium-transition metal sulfate compound, and the like can be given. In some cases, two or more positive electrode active materials may be used in combination. Preferably, from the viewpoint of capacity and output characteristics, a lithium-transition metal composite oxide is used as the positive electrode active material. More preferably, a composite oxide containing lithium and nickel is used. More preferably, Li (Ni—Mn—Co) O 2 and those in which part of these transition metals are substituted by other elements (hereinafter, also simply referred to as “NMC composite oxide”), or lithium-nickel-cobalt An aluminum composite oxide (hereinafter, also simply referred to as “NCA composite oxide”) or the like is used. The NMC composite oxide has a layered crystal structure in which a lithium atomic layer and a transition metal (Mn, Ni and Co are arranged in order) atomic layer are alternately stacked via an oxygen atomic layer. One Li atom is contained per transition metal atom, and the amount of Li that can be extracted is twice that of the spinel-based lithium manganese oxide, that is, the supply capacity is doubled, and a high capacity can be obtained.
　（負極活物質）
　負極活物質としては、例えば、グラファイト（黒鉛）、ソフトカーボン、ハードカーボン等の炭素材料、リチウム－遷移金属複合酸化物（例えば、Ｌｉ４Ｔｉ５Ｏ１２）、金属材料（スズ、シリコン）、リチウム合金系負極材料（例えばリチウム－スズ合金、リチウム－シリコン合金、リチウム－アルミニウム合金、リチウム－アルミニウム－マンガン合金等）などが挙げられる。場合によっては、２種以上の負極活物質が併用されてもよい。好ましくは、容量、出力特性の観点から、炭素材料、リチウム－遷移金属複合酸化物、リチウム合金系負極材料が、負極活物質として好ましく用いられる。なお、上記以外の負極活物質が用いられてもよいことは勿論である。また、（メタ）アクリレート系共重合体等の被覆用樹脂は特に炭素材料に対して付着しやすいという性質を有している。したがって、構造的に安定した電極材料を提供するという観点からは、負極活物質として炭素材料を用いることが好ましい。 (Negative electrode active material)
Examples of the negative electrode active material include carbon materials such as graphite (graphite), soft carbon, and hard carbon; lithium-transition metal composite oxides (eg, Li 4 Ti 5 O 12 ); metal materials (tin, silicon); Alloy-based negative electrode materials (eg, lithium-tin alloy, lithium-silicon alloy, lithium-aluminum alloy, lithium-aluminum-manganese alloy, and the like) and the like. In some cases, two or more negative electrode active materials may be used in combination. Preferably, from the viewpoint of capacity and output characteristics, carbon materials, lithium-transition metal composite oxides, and lithium alloy-based negative electrode materials are preferably used as the negative electrode active material. In addition, it goes without saying that a negative electrode active material other than the above may be used. Further, a coating resin such as a (meth) acrylate-based copolymer has a property of easily adhering particularly to a carbon material. Therefore, from the viewpoint of providing a structurally stable electrode material, it is preferable to use a carbon material as the negative electrode active material.
　（導電助剤）
　図９に示すように、導電助剤１６４は、被覆用樹脂１６３とともに電極活物質１６１の表面を被覆する被覆剤１６２として用いられる。導電助剤１６４は、被覆剤中で電子伝導パスを形成し、電極活物質層１３２の電子移動抵抗を低減することで、電池の高レートでの出力特性向上に寄与し得る。 (Conduction aid)
As shown in FIG. 9, the conductive assistant 164 is used together with the coating resin 163 as a coating agent 162 for coating the surface of the electrode active material 161. The conductive auxiliary agent 164 can contribute to improving the output characteristics of the battery at a high rate by forming an electron conductive path in the coating agent and reducing the electron transfer resistance of the electrode active material layer 132.
　導電助剤１６４としては、例えば、アルミニウム、ステンレス、銀、金、銅、チタン等の金属、これらの金属を含む合金または金属酸化物；グラファイト、炭素繊維（具体的には、気相成長炭素繊維（ＶＧＣＦ）等）、カーボンナノチューブ（ＣＮＴ）、カーボンブラック（具体的には、アセチレンブラック、ケッチェンブラック（登録商標）、ファーネスブラック、チャンネルブラック、サーマルランプブラック等）等のカーボンが挙げられるが、これらに限定されない。また、粒子状のセラミック材料や樹脂材料の周りに上記金属材料をめっき等でコーティングしたものも導電助剤として使用できる。これらの導電助剤のなかでも、電気的安定性の観点から、アルミニウム、ステンレス、銀、金、銅、チタン、およびカーボンからなる群より選択される少なくとも１種を含むことが好ましく、アルミニウム、ステンレス、銀、金、およびカーボンからなる群より選択される少なくとも１種を含むことがより好ましく、カーボンを少なくとも１種を含むことがさらに好ましい。これらの導電助剤は、１種のみを単独で使用してもよいし、２種以上を併用しても構わない。 Examples of the conductive additive 164 include metals such as aluminum, stainless steel, silver, gold, copper, and titanium; alloys and metal oxides containing these metals; graphite, carbon fibers (specifically, vapor grown carbon fibers). (VGCF), carbon nanotubes (CNT), carbon black (specifically, acetylene black, Ketjen black (registered trademark), furnace black, channel black, thermal lamp black, etc.). It is not limited to these. Further, a material obtained by coating the above-described metal material around a particulate ceramic material or resin material by plating or the like can also be used as the conductive assistant. Among these conductive aids, from the viewpoint of electrical stability, it is preferable to include at least one selected from the group consisting of aluminum, stainless steel, silver, gold, copper, titanium, and carbon. , Silver, gold, and carbon, and more preferably at least one carbon. One of these conductive assistants may be used alone, or two or more thereof may be used in combination.
　導電助剤１６４の形状は、図９に示すような粒子状または繊維状であることが好ましい。導電助剤１６４が粒子状である場合、粒子の形状は特に限定されず、粉末状、球状、棒状、針状、板状、柱状、不定形状、燐片状、紡錘状等、いずれの形状であっても構わない。導電助剤が粒子状である場合の平均粒子径（一次粒子径）は、１００ｎｍ以下であることが好ましい。なお、本明細書中において、「粒子径」とは、導電助剤の輪郭線上の任意の２点間の距離のうち、最大の距離を意味する。「平均粒子径」の値としては、走査型電子顕微鏡（ＳＥＭ）や透過型電子顕微鏡（ＴＥＭ）等の観察手段を用い、数～数十視野中に観察される粒子の粒子径の平均値として算出される値を採用するものとする。 The shape of the conductive additive 164 is preferably in the form of particles or fibers as shown in FIG. When the conductive additive 164 is in the form of particles, the shape of the particles is not particularly limited, and may be any shape such as a powder, a sphere, a rod, a needle, a plate, a column, an irregular shape, a scale, and a spindle. It does not matter. The average particle diameter (primary particle diameter) when the conductive auxiliary is in the form of particles is preferably 100 nm or less. In addition, in this specification, "particle diameter" means the largest distance among the distances between any two points on the outline of the conductive additive. The value of the “average particle diameter” is determined by using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) as an average value of the particle diameters of particles observed in several to several tens of visual fields. It is assumed that the calculated value is adopted.
　（導電部材）
　導電部材１６５は、電極活物質層１３２中で電子伝導パスを形成する機能を有する。特に、図９に示すように、導電部材１６５の少なくとも一部が、電極活物質層１３２の２つの主面Ｓ１、Ｓ２同士を電気的に接続する導電通路を形成していることが好ましい。このような形態を有することで、電極活物質層１３２中の厚さ方向（発電要素１１１の積層方向）の電子移動抵抗がさらに低減されるため、電池の高レートでの出力特性をより一層向上しうる。なお、導電部材１６５の少なくとも一部が、電極活物質層１３２の２つの主面Ｓ１、Ｓ２同士を電気的に接続する導電通路を形成しているか否かは、ＳＥＭや光学顕微鏡を用いて電極活物質層１３２の断面を観察することにより確認することができる。 (Conductive member)
The conductive member 165 has a function of forming an electron conduction path in the electrode active material layer 132. In particular, as shown in FIG. 9, it is preferable that at least a part of the conductive member 165 forms a conductive path that electrically connects the two main surfaces S1 and S2 of the electrode active material layer 132. With such a configuration, the electron transfer resistance in the thickness direction (the stacking direction of the power generation elements 111) in the electrode active material layer 132 is further reduced, so that the output characteristics at a high rate of the battery are further improved. Can. Note that whether or not at least a part of the conductive member 165 forms a conductive path for electrically connecting the two main surfaces S1 and S2 of the electrode active material layer 132 is determined by using an SEM or an optical microscope. It can be confirmed by observing the cross section of the active material layer 132.
　導電部材１６５は、繊維状の形態を有する導電性繊維であることが好ましい。具体的には、ＰＡＮ系炭素繊維、ピッチ系炭素繊維等の炭素繊維、合成繊維の中に導電性のよい金属や黒鉛を均一に分散させてなる導電性繊維、ステンレスのような金属を繊維化した金属繊維、有機物繊維の表面を金属で被覆した導電性繊維、有機物繊維の表面を、導電性物質を含む樹脂で被覆した導電性繊維等が挙げられる。なかでも、導電性に優れ、軽量であることから炭素繊維が好ましい。 The conductive member 165 is preferably a conductive fiber having a fibrous form. Specifically, carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers obtained by uniformly dispersing a highly conductive metal or graphite in synthetic fibers, and metals such as stainless steel are formed into fibers. Metal fibers, conductive fibers in which the surfaces of organic fibers are coated with metal, and conductive fibers in which the surfaces of organic fibers are coated with a resin containing a conductive substance. Among them, carbon fibers are preferred because they have excellent conductivity and are lightweight.
　なお、本実施形態の電池１００においては、電極活物質層１３２の構成部材として、上記の電極活物質や、必要に応じて用いられる導電部材１６５、イオン伝導性ポリマー、リチウム塩、被覆剤（被覆用樹脂、導電助剤）以外の部材を適宜使用しても構わない。しかしながら、電池のエネルギー密度を向上させる観点から、例えば結着剤等の充放電反応の進行にあまり寄与しない部材は、含有させないほうが好ましい。 In the battery 100 of the present embodiment, as the constituent members of the electrode active material layer 132, the above-described electrode active material, a conductive member 165 used as needed, an ion conductive polymer, a lithium salt, and a coating agent (coating). Other than the resin for use and the conductive auxiliary). However, from the viewpoint of improving the energy density of the battery, it is preferable not to include a member such as a binder that does not contribute much to the progress of the charge / discharge reaction.
　本実施形態の電池１００において、電極活物質層１３２の厚さｔ（図９を参照して、主面Ｓ１、Ｓ２間の距離）は、正極活物質層１３２ａについては、好ましくは１５０～１５００μｍであり、より好ましくは１８０～９５０μｍであり、さらに好ましくは２００～８００μｍである。また、負極活物質層１３２ｂの厚さは、好ましくは１５０～１５００μｍであり、より好ましくは１８０～１２００μｍであり、さらに好ましくは２００～１０００μｍである。電極活物質層１３２の厚さが上述した下限値以上の値であれば、電池のエネルギー密度を十分に高めることができる。一方、電極活物質層１３２の厚さが上述した上限値以下の値であれば、電極活物質層１３２の構造を十分に維持することができる。なお、電極活物質層１３２の厚さｔは、主面Ｓ１、Ｓ２の面方向において常に一定であるとは限らず、面方向によってばらついていることもある。 In the battery 100 of the present embodiment, the thickness t (the distance between the main surfaces S1 and S2 with reference to FIG. 9) of the electrode active material layer 132 is preferably 150 to 1500 μm for the positive electrode active material layer 132a. Yes, more preferably 180 to 950 μm, even more preferably 200 to 800 μm. Further, the thickness of the negative electrode active material layer 132b is preferably 150 to 1500 μm, more preferably 180 to 1200 μm, and still more preferably 200 to 1000 μm. When the thickness of the electrode active material layer 132 is equal to or greater than the above lower limit, the energy density of the battery can be sufficiently increased. On the other hand, when the thickness of the electrode active material layer 132 is equal to or less than the above upper limit, the structure of the electrode active material layer 132 can be sufficiently maintained. Note that the thickness t of the electrode active material layer 132 is not always constant in the plane direction of the main surfaces S1 and S2, and may vary depending on the plane direction.
　また、発電要素１１１の積層方向を投影方向としたとき、正極活物質層１３２ａの投影面積は、好ましくは５０～１５００ｃｍ２であり、より好ましくは１８０～９５０ｃｍ２であり、さらに好ましくは２００～８００ｃｍ２である。また、負極活物質層１３２ｂの投影面積は、好ましくは５０～１５００ｃｍ２であり、より好ましくは２００～１５００ｃｍ２であり、さらに好ましくは５００～１５００ｃｍ２である。電極活物質層１３２の投影面積が大きいほど、電池容量を高めることができる一方で、電極１３０は変形し易くなるため本発明の効果は顕著に現れる。 When the stacking direction of the power generation elements 111 is the projection direction, the projected area of the positive electrode active material layer 132a is preferably 50 to 1500 cm 2 , more preferably 180 to 950 cm 2 , and still more preferably 200 to 800 cm 2. 2 . The projected area of the negative electrode active material layer 132b is preferably from 50 to 1500 cm 2 , more preferably from 200 to 1500 cm 2 , and still more preferably from 500 to 1500 cm 2 . As the projected area of the electrode active material layer 132 is larger, the battery capacity can be increased, while the electrode 130 is easily deformed, so that the effect of the present invention is remarkably exhibited.
　発電要素１１の積層方向を投影方向としたとき、電極活物質層１３２の投影面積に対する接触面２０Ｓの面積の割合は、好ましくは５０％以上であり、より好ましくは７０％以上であり、さらに好ましくは８０％以上であり、特に好ましくは９０％以上である。電極活物質層１３２の投影面積に対する接触面２０Ｓの面積の割合が大きいほど、接触面２０Ｓから電極１３０に加わる面圧を分散することができるため、面圧分布を低減して電極１３０の変形を抑制する効果がより一層顕著となる。 When the stacking direction of the power generation elements 11 is the projection direction, the ratio of the area of the contact surface 20S to the projection area of the electrode active material layer 132 is preferably 50% or more, more preferably 70% or more, and still more preferably. Is at least 80%, particularly preferably at least 90%. The larger the ratio of the area of the contact surface 20S to the projected area of the electrode active material layer 132, the more the surface pressure applied to the electrode 130 from the contact surface 20S can be dispersed, so that the surface pressure distribution is reduced and the deformation of the electrode 130 is reduced. The suppression effect becomes more remarkable.
　［電解質層］
　電解質層１４０に使用される電解質は、特に制限はなく、液体電解質（電解液）、ゲルポリマー電解質などが制限なく用いられる。これらの電解質を用いることで、高いリチウムイオン伝導性が確保されうる。 [Electrolyte layer]
The electrolyte used for the electrolyte layer 140 is not particularly limited, and a liquid electrolyte (electrolyte), a gel polymer electrolyte, or the like is used without any limitation. By using these electrolytes, high lithium ion conductivity can be ensured.
　本形態では、電解質層１４０にセパレータを用いてもよい。セパレータは、電解質を保持して正極１３０ａと負極１３０ｂとの間のリチウムイオン伝導性を確保する機能、および正極１３０ａと負極１３０ｂとの間の隔壁としての機能を有する。特に電解質として液体電解質（電解液）を使用する場合には、セパレータを用いることが好ましい。セパレータの形態としては、例えば、上記電解質を吸収保持するポリマーや繊維からなる多孔性シートのセパレータや不織布セパレータ等を挙げることができる。 In this embodiment, a separator may be used for the electrolyte layer 140. The separator has a function of retaining electrolyte and ensuring lithium ion conductivity between the positive electrode 130a and the negative electrode 130b, and a function as a partition between the positive electrode 130a and the negative electrode 130b. In particular, when a liquid electrolyte (electrolyte solution) is used as the electrolyte, it is preferable to use a separator. Examples of the form of the separator include a porous sheet separator and a nonwoven fabric separator made of a polymer or a fiber that absorbs and retains the electrolyte.
　電解液（液体電解質）は、上述の電極活物質層１３２に使用される電解液と同様のものが用いられうる。なお、電解液におけるリチウム塩の濃度は、０．１～３．０Ｍであることが好ましく、０．８～２．２Ｍであることがより好ましい。また、添加剤を使用する場合の使用量は、添加剤を添加する前の電解液１００質量％に対して、好ましくは０．５～１０質量％、より好ましくは０．５～５質量％である。 As the electrolytic solution (liquid electrolyte), the same as the electrolytic solution used for the above-described electrode active material layer 132 can be used. The concentration of the lithium salt in the electrolyte is preferably from 0.1 to 3.0 M, more preferably from 0.8 to 2.2 M. When the additive is used, the amount of the additive is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, based on 100% by mass of the electrolyte before adding the additive. is there.
　添加剤としては、例えば、ビニレンカーボネート、メチルビニレンカーボネート、ジメチルビニレンカーボネート、フェニルビニレンカーボネート、ジフェニルビニレンカーボネート、エチルビニレンカーボネート、ジエチルビニレンカーボネート、ビニルエチレンカーボネート、１，２－ジビニルエチレンカーボネート、１－メチル－１－ビニルエチレンカーボネート、１－メチル－２－ビニルエチレンカーボネート、１－エチル－１－ビニルエチレンカーボネート、１－エチル－２－ビニルエチレンカーボネート、ビニルビニレンカーボネート、アリルエチレンカーボネート、ビニルオキシメチルエチレンカーボネート、アリルオキシメチルエチレンカーボネート、アクリルオキシメチルエチレンカーボネート、メタクリルオキシメチルエチレンカーボネート、エチニルエチレンカーボネート、プロパルギルエチレンカーボネート、エチニルオキシメチルエチレンカーボネート、プロパルギルオキシエチレンカーボネート、メチレンエチレンカーボネート、１，１－ジメチル－２－メチレンエチレンカーボネートなどが挙げられる。なかでも、ビニレンカーボネート、メチルビニレンカーボネート、ビニルエチレンカーボネートが好ましく、ビニレンカーボネート、ビニルエチレンカーボネートがより好ましい。これらの環式炭酸エステルは、１種のみが単独で用いられてもよいし、２種以上が併用されてもよい。 Examples of the additive include vinylene carbonate, methyl vinylene carbonate, dimethyl vinylene carbonate, phenyl vinylene carbonate, diphenyl vinylene carbonate, ethyl vinylene carbonate, diethyl vinylene carbonate, vinyl ethylene carbonate, 1,2-divinyl ethylene carbonate, and 1-methyl- 1-vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-1-vinylethylene carbonate, 1-ethyl-2-vinylethylene carbonate, vinylvinylene carbonate, allylethylene carbonate, vinyloxymethylethylene carbonate, Allyloxymethyl ethylene carbonate, acryloxymethyl ethylene carbonate, methacryloxymethyl Ethylene carbonate, ethynyl ethylene carbonate, propargyl carbonate, ethynyloxy methylethylene carbonate, propargyloxy ethylene carbonate, methylene carbonate, etc. 1,1-dimethyl-2-methylene-ethylene carbonate. Among them, vinylene carbonate, methyl vinylene carbonate and vinyl ethylene carbonate are preferred, and vinylene carbonate and vinyl ethylene carbonate are more preferred. One of these cyclic carbonates may be used alone, or two or more thereof may be used in combination.
　ゲルポリマー電解質は、イオン伝導性ポリマーからなるマトリックスポリマー（ホストポリマー）に、上記の電解液が注入されてなる構成を有する。電解質としてゲルポリマー電解質を用いることで電解質の流動性がなくなり、各層間のイオン伝導性を遮断することで容易になる点で優れている。マトリックスポリマー（ホストポリマー）として用いられるイオン伝導性ポリマーとしては、例えば、ポリエチレンオキシド（ＰＥＯ）、ポリプロピレンオキシド（ＰＰＯ）、ポリエチレングリコール（ＰＥＧ）、ポリアクリロニトリル（ＰＡＮ）、ポリフッ化ビニリデン－ヘキサフルオロプロピレン（ＰＶｄＦ－ＨＥＰ）、ポリメチルメタクリレート（ＰＭＭＡ）およびこれらの共重合体等が挙げられる。 The gel polymer electrolyte has a configuration in which the above-mentioned electrolyte is injected into a matrix polymer (host polymer) made of an ion conductive polymer. The use of a gel polymer electrolyte as the electrolyte is excellent in that the fluidity of the electrolyte is lost and the ionic conductivity between the layers is cut off to facilitate the flow. Examples of the ion conductive polymer used as the matrix polymer (host polymer) include, for example, polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene ( PVdF-HEP), polymethyl methacrylate (PMMA), and copolymers thereof.
　ゲルポリマー電解質のマトリックスポリマーは、架橋構造を形成することによって、優れた機械的強度を発現しうる。架橋構造を形成させるには、適当な重合開始剤を用いて、高分子電解質形成用の重合性ポリマー（例えば、ＰＥＯやＰＰＯ）に対して熱重合、紫外線重合、放射線重合、電子線重合等の重合処理を施せばよい。 マ ト リ ッ ク ス The matrix polymer of the gel polymer electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, a suitable polymerization initiator is used to polymerize a polymerizable polymer for forming a polymer electrolyte (eg, PEO or PPO) by heat polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, or the like. A polymerization treatment may be performed.
　［正極集電板および負極集電板］
　集電板１３４ａ、１３４ｂを構成する材料は、特に制限されず、リチウムイオン二次電池用の集電板として従来用いられている公知の高導電性材料が用いられうる。集電板１３４ａ、１３４ｂの構成材料としては、例えば、アルミニウム、銅、チタン、ニッケル、ステンレス、これらの合金等の金属材料が好ましい。軽量、耐食性、高導電性の観点から、より好ましくはアルミニウム、銅であり、特に好ましくはアルミニウムである。なお、正極集電板１３４ａと負極集電板１３４ｂとでは、同一の材料が用いられてもよいし、異なる材料が用いられてもよい。 [Positive current collector and negative current collector]
The material forming the current collectors 134a and 134b is not particularly limited, and a known highly conductive material conventionally used as a current collector for a lithium ion secondary battery can be used. As a constituent material of the current collectors 134a and 134b, for example, a metal material such as aluminum, copper, titanium, nickel, stainless steel, or an alloy thereof is preferable. From the viewpoint of light weight, corrosion resistance, and high conductivity, aluminum and copper are more preferable, and aluminum is particularly preferable. Note that the same material may be used for the positive electrode current collector 134a and the negative material may be used for the negative electrode current collector 134b.
　［シール部］
　シール部１５０は、集電体１３１同士の接触や単セル１２０の端部における短絡を防止する機能を有する。シール部１５０を構成する材料としては、絶縁性、シール性（液密性）、電池動作温度下での耐熱性等を有するものであればよい。例えば、アクリル樹脂、ウレタン樹脂、エポキシ樹脂、ポリエチレン樹脂、ポリプロピレン樹脂、ポリイミド樹脂、ゴム（エチレン－プロピレン－ジエンゴム：ＥＰＤＭ）、等が用いられうる。また、イソシアネート系接着剤や、アクリル樹脂系接着剤、シアノアクリレート系接着剤などを用いてもよく、ホットメルト接着剤（ウレタン樹脂、ポリアミド樹脂、ポリオレフィン樹脂）などを用いてもよい。なかでも、耐食性、耐薬品性、作り易さ（製膜性）、経済性等の観点から、ポリエチレン樹脂やポリプロピレン樹脂が、絶縁層の構成材料として好ましく用いられ、非結晶性ポリプロピレン樹脂を主成分とするエチレン、プロピレン、ブテンを共重合した樹脂を用いることが好ましい。 [Seal part]
The seal portion 150 has a function of preventing contact between the current collectors 131 and a short circuit at an end of the unit cell 120. The material forming the seal portion 150 may be any material that has insulation properties, seal properties (liquid tightness), heat resistance at the battery operating temperature, and the like. For example, acrylic resin, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber (ethylene-propylene-diene rubber: EPDM) and the like can be used. Further, an isocyanate-based adhesive, an acrylic resin-based adhesive, a cyanoacrylate-based adhesive, or the like, or a hot melt adhesive (urethane resin, polyamide resin, polyolefin resin), or the like may be used. Among them, polyethylene resin or polypropylene resin is preferably used as a constituent material of the insulating layer from the viewpoint of corrosion resistance, chemical resistance, ease of production (film forming property), economy, etc., and non-crystalline polypropylene resin is a main component. It is preferable to use a resin obtained by copolymerizing ethylene, propylene, and butene.
　［外装体］
　図８に示すように、外装体１１２は、可撓性を有するシート材によって構成さる。可撓性を有するシート材としては、特に限定されないが、高出力化や冷却性能に優れ、ＥＶ、ＨＥＶ用の大型機器用電池に好適に利用することができるという観点からはラミネートフィルムによって構成することが好ましい。ラミネートフィルムには、例えば、ポリプロピレン（ＰＰ）、アルミニウム、ナイロンをこの順に積層してなる３層構造のラミネートフィルム等を用いることができるが、これらに何ら制限されるものではない。また、外部から掛かる発電要素１１１への群圧を容易に調整することができることから、外装体１１２はアルミネートラミネートがより好ましい。 [Outer body]
As shown in FIG. 8, the exterior body 112 is made of a flexible sheet material. The sheet material having flexibility is not particularly limited, but is composed of a laminate film from the viewpoint that it is excellent in high output and cooling performance and can be suitably used for batteries for large-sized devices for EV and HEV. Is preferred. As the laminate film, for example, a laminate film having a three-layer structure in which polypropylene (PP), aluminum, and nylon are laminated in this order can be used, but the laminate film is not limited thereto. Further, since the group pressure applied to the power generation element 111 from the outside can be easily adjusted, the exterior body 112 is more preferably made of an alumina laminate.
　以上説明したように、本形態に係る電池パック１０は、電池１００と、冷却部２０と、を有する。ここで、電池１００は、電極活物質１６１を含む非結着体からなる電極活物質層１３２が集電体１３１の表面に形成されてなる電極１３０を有する発電要素１１１が可撓性を有する外装体１１２に収容されてなる。冷却部２０は、冷媒ＣＭを保持する内部空間２０Ａを形成し、発電要素１１の積層方向から電池１００の表面１００Ｓの少なくとも一部に対して加圧した状態で接触する接触面２０Ｓを備える。冷却部２０は、接触面２０Ｓの面方向に沿って平坦な平坦部２１と、接触面２０Ｓの面方向に断続的に配置され、平坦部２１の一部から内部空間２０Ａ側に向かって凹み、内部空間２０Ａに冷媒ＣＭの流路を区画形成する複数の凹部２２と、を備える。 As described above, the battery pack 10 according to the present embodiment includes the battery 100 and the cooling unit 20. Here, the battery 100 includes a power generation element 111 having an electrode 130 in which an electrode active material layer 132 made of a non-binder including an electrode active material 161 is formed on the surface of a current collector 131. It is housed in the body 112. The cooling unit 20 has an internal space 20A that holds the refrigerant CM, and includes a contact surface 20S that contacts at least a part of the surface 100S of the battery 100 in a pressurized direction from the stacking direction of the power generation element 11. The cooling unit 20 is disposed intermittently in the plane direction of the contact surface 20S and the flat portion 21 flat along the surface direction of the contact surface 20S, and is recessed from a part of the flat portion 21 toward the internal space 20A side, A plurality of recesses 22 that define the flow path of the refrigerant CM in the internal space 20A.
　上記構成を備える電池パック１０によれば、冷却部２０の接触面２０Ｓによって電池１００に対して均等な面圧を付与できる。また、冷媒ＣＭの流路を区画形成するための凹部２２が面圧方向に断続的に（不連続に）配置されているため、面圧の抜けが生じる部分が面方向に分散する。これにより、面圧分布を低減して電極１３０の変形を抑制することができる。 According to the battery pack 10 having the above configuration, the contact surface 20S of the cooling unit 20 can apply a uniform surface pressure to the battery 100. Further, since the concave portions 22 for partitioning the flow path of the refrigerant CM are intermittently (discontinuously) arranged in the surface pressure direction, portions where the surface pressure is released are dispersed in the surface direction. Thereby, the surface pressure distribution can be reduced and the deformation of the electrode 130 can be suppressed.
　また、冷却部２０の接触面２０Ｓの面積は、発電要素１１の積層方向を投影方向とした場合の凹部２２の投影面積よりも大きくなるように構成することが好ましい。これにより、面圧抜けが生じる凹部２２の投影面積に比べて、均等な面圧を付与する接触面２０Ｓの面積を大きくすることができるため、面圧分布を低減して電極１３０の変形を抑制する効果が顕著となる。 Further, it is preferable that the area of the contact surface 20S of the cooling unit 20 is configured to be larger than the projection area of the concave portion 22 when the stacking direction of the power generation elements 11 is the projection direction. Accordingly, the area of the contact surface 20S for applying a uniform surface pressure can be increased as compared with the projection area of the concave portion 22 where the surface pressure is released, so that the surface pressure distribution is reduced and the deformation of the electrode 130 is suppressed. The effect of this is remarkable.
　また、冷却部２０は、平坦部２１および複数の凹部２２を備える複数の冷却板２３、２４を有することが好ましい。隣り合う冷却板２３、２４の間には、内部空間２０Ａが形成される。このように、冷却板２３、２４を用いることによって簡単な構成で冷却部２０を容易に製造することができる。 冷却 Moreover, it is preferable that the cooling unit 20 includes a plurality of cooling plates 23 and 24 having a flat portion 21 and a plurality of concave portions 22. An internal space 20A is formed between the adjacent cooling plates 23 and 24. As described above, by using the cooling plates 23 and 24, the cooling unit 20 can be easily manufactured with a simple configuration.
　また、発電要素１１の積層方向を投影方向としたとき、電極活物質層１３２の投影面積に対する接触面２０Ｓの面積の割合は、５０％以上であることが好ましい。電極活物質層１３２の投影面積に対する接触面２０Ｓの面積の割合が大きいほど、接触面２０Ｓから電極１３０に加わる面圧を分散することができるため、面圧分布を低減して電極１３０の変形を抑制する効果がより一層顕著となる。 (4) When the stacking direction of the power generation elements 11 is the projection direction, the ratio of the area of the contact surface 20S to the projection area of the electrode active material layer 132 is preferably 50% or more. The larger the ratio of the area of the contact surface 20S to the projected area of the electrode active material layer 132, the more the surface pressure applied to the electrode 130 from the contact surface 20S can be dispersed, so that the surface pressure distribution is reduced and the deformation of the electrode 130 is reduced. The suppression effect becomes more remarkable.
　また、接触面２０Ｓから電池１００に付与される加圧力は、２０ｋＰａ以上であることが好ましい。非結着活物質層を用いた場合の電池１００の内部抵抗は加圧力に対して感度があり、乾燥電極の場合よりも大きな加圧力を印加しなければ電池１００の内部抵抗が十分に低下しない。また、加圧力が大きい場合、電池１００対して偏荷重がかかった際に、非結着活物質層が変形しやすくなる。このため、接触面２０Ｓの面圧を均等にして非結着活物質層の変形を抑制する本発明の作用効果をより一層顕著に発現させることができる。 加 Further, the pressure applied to battery 100 from contact surface 20S is preferably 20 kPa or more. The internal resistance of the battery 100 when the non-binding active material layer is used is sensitive to the pressing force, and the internal resistance of the battery 100 does not sufficiently decrease unless a larger pressing force is applied than in the case of the dry electrode. . When the pressing force is large, the non-binding active material layer is easily deformed when an uneven load is applied to the battery 100. For this reason, the effect of the present invention that suppresses the deformation of the non-binding active material layer by equalizing the surface pressure of the contact surface 20S can be more remarkably exhibited.
　本発明は前述した実施形態において説明した内容のみに限定されることはなく、特許請求の範囲の記載に基づいて適宜変更することが可能である。以下、変形例の一例について説明する。なお、前述した実施形態と同様の構成については、同一の符号を付してその説明を省略する。 The present invention is not limited to the contents described in the above-described embodiment, but can be appropriately changed based on the description in the claims. Hereinafter, an example of the modified example will be described. In addition, about the structure similar to embodiment mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted.
　＜変形例１＞
　図１０は、変形例１に係る電池パックの冷却部内の冷媒の流れを示す概略図である。前述した実施形態では、図２に示すように複数の冷却部２０は同じ方向（Ｙ方向）に冷媒ＣＭを流通させるとして説明したが、これに限定されず、図１０に示すように冷却部２０間で冷媒ＣＭの流れ方向Ｆが異なっていてもよい。冷媒ＣＭは、電池１００を冷却するために吸熱するため、供給口２０ｉから排出口２０ｏに向かって温度が上昇する。このため、図１０のように冷媒ＣＭの流れ方向で冷却部２０間で異ならせることによって、電池パック全体において、冷媒ＣＭの流れ方向Ｆの温度差を低減することができる。 <Modification 1>
FIG. 10 is a schematic diagram illustrating the flow of the refrigerant in the cooling unit of the battery pack according to the first modification. In the above-described embodiment, as described in FIG. 2, the plurality of cooling units 20 are described as allowing the coolant CM to flow in the same direction (Y direction). However, the present invention is not limited to this, and as illustrated in FIG. The flow direction F of the refrigerant CM may be different between them. Since the coolant CM absorbs heat to cool the battery 100, the temperature increases from the supply port 20i to the discharge port 20o. Therefore, by making the flow direction of the refrigerant CM different between the cooling units 20 as shown in FIG. 10, the temperature difference in the flow direction F of the refrigerant CM in the entire battery pack can be reduced.
　＜変形例２＞
　図１１は、変形例２に係る電池パックの一部を拡大して示す断面図である。変形例２に係る電池パックの冷却部２２０は、電池１００と平坦部２１との間に配置される面圧分散板２６をさらに有する点で前述した実施形態と異なる。 <Modification 2>
FIG. 11 is a cross-sectional view illustrating a part of a battery pack according to Modification Example 2 in an enlarged manner. The cooling unit 220 of the battery pack according to Modification 2 is different from the above-described embodiment in that the cooling unit 220 further includes a surface pressure distribution plate 26 disposed between the battery 100 and the flat portion 21.
　図１１に示すように、面圧分散板２６は、電池１００の表面１００Ｓに直接的に接触するため、接触面２０Ｓは面圧分散板２６の電池１００に対向する面２６Ｓのうち電池１００に接触する面によって構成される。面圧分散板２６は、平板によって構成される。面圧分散板２６は、冷媒ＣＭによって冷却された平坦部２１の平坦面２１Ｓと面接触して冷却される。冷却された面圧分散板２６は、接触面２０Ｓを介して電池１００を冷却する。面圧分散板２６を配置することによって、接触面２０Ｓの面積が増えるため、面圧分布をより一層低減することができる。 As shown in FIG. 11, since the surface pressure distribution plate 26 directly contacts the surface 100S of the battery 100, the contact surface 20S contacts the battery 100 of the surface 26S of the surface pressure distribution plate 26 facing the battery 100. It is constituted by the surface to do. The surface pressure distribution plate 26 is configured by a flat plate. The surface pressure distribution plate 26 is cooled by surface contact with the flat surface 21S of the flat portion 21 cooled by the refrigerant CM. The cooled surface pressure distribution plate 26 cools the battery 100 via the contact surface 20S. By arranging the surface pressure distribution plate 26, the area of the contact surface 20S increases, so that the surface pressure distribution can be further reduced.
　面圧分散板２６の構成材料は、電池１００の熱を冷媒ＣＭへ伝達できる程度に熱伝導性の高い材料であれば特に限定されないが、例えば銅やアルミニウム等の金属材料を用いることができる。面圧分散板２６の積層方向の厚さは、電池１００の熱を冷媒ＣＭへ伝達できる程度に薄い限りにおいて特に限定されないが、好ましくは０．１～１０ｍｍであり、より好ましくは０．２～５ｍｍであり、さらに好ましくは０．５～３ｍｍである。 構成 The constituent material of the surface pressure dispersion plate 26 is not particularly limited as long as it is a material having high thermal conductivity to the extent that the heat of the battery 100 can be transmitted to the coolant CM. For example, a metal material such as copper or aluminum can be used. The thickness of the surface pressure dispersion plate 26 in the stacking direction is not particularly limited as long as it is thin enough to transmit the heat of the battery 100 to the refrigerant CM, but is preferably 0.1 to 10 mm, more preferably 0.2 to 10 mm. 5 mm, more preferably 0.5 to 3 mm.
　なお、面圧分散板２６を配置した場合においても、電池１００は、平坦部２１の平坦面２１Ｓから面圧を受ける。したがって、面圧の抜けが生じる凹部が面方向に連続的に配置されている場合は、電池１００の電極１３０にかかる面圧が局所的に偏在化して電極１３０が変形する可能性がある。したがって、本変形例２においても、本発明の形態のように凹部２２が面方向に断続的に配置されることによって、面圧分布を低減して電極１３０の変形を抑制する効果を発揮する。 電池 Even when the surface pressure distribution plate 26 is arranged, the battery 100 receives the surface pressure from the flat surface 21S of the flat portion 21. Therefore, when the concave portions in which the surface pressure is released are continuously arranged in the surface direction, the surface pressure applied to the electrode 130 of the battery 100 may be locally localized and the electrode 130 may be deformed. Therefore, also in Modification Example 2, the concave portions 22 are intermittently arranged in the plane direction as in the embodiment of the present invention, thereby exhibiting an effect of reducing the surface pressure distribution and suppressing the deformation of the electrode 130.
　以下、図１２～図１３を参照して、変形例３～５に係る冷却部の凹部の形状について説明する。 Hereinafter, with reference to FIGS. 12 and 13, the shapes of the concave portions of the cooling units according to Modification Examples 3 to 5 will be described.
　＜変形例３＞
　図１２は、変形例３に係る冷却部の凹部３２２の形状を示す上面図である。変形例３に係る冷却部の凹部３２２は、積層方向を投影方向としたとき、冷媒ＣＭの流れ方向Ｆに向かって投影面積が小さくなるように形成されている。これにより、冷却部の内部空間では、凹部３２２によって区画形成される冷媒ＣＭの流路の断面積が冷媒ＣＭの流れ方向Ｆに向かって大きくなる。その結果、冷媒ＣＭの流れ方向Ｆに向かって流路の圧力損失が小さくなるため、冷媒ＣＭを円滑に循環させることができ、冷却部による冷却効率を高めることができる。 <Modification 3>
FIG. 12 is a top view illustrating the shape of the concave portion 322 of the cooling unit according to the third modification. The concave portion 322 of the cooling unit according to Modification 3 is formed such that the projected area decreases toward the flow direction F of the coolant CM when the stacking direction is the projection direction. Thereby, in the internal space of the cooling unit, the cross-sectional area of the flow path of the refrigerant CM defined by the recess 322 increases in the flow direction F of the refrigerant CM. As a result, the pressure loss in the flow path decreases in the flow direction F of the refrigerant CM, so that the refrigerant CM can be smoothly circulated, and the cooling efficiency of the cooling unit can be increased.
　＜変形例４＞
　図１３は、変形例４に係る冷却部の凹部４２２の形状を示す上面図である。変形例４に係る冷却部の凹部４２２は、積層方向から見て、冷媒ＣＭの供給側（流れ方向Ｆと逆側）が先細り形状を有する。これにより、凹部４２２は流れに対する抵抗が小さくなるため、流れ方向Ｆに向かって流れる冷媒ＣＭの流れを阻害することなく、円滑な冷媒ＣＭの流れを形成することができる。 <Modification 4>
FIG. 13 is a top view illustrating the shape of the recess 422 of the cooling unit according to the fourth modification. The concave portion 422 of the cooling unit according to Modification Example 4 has a tapered shape on the supply side of the coolant CM (the side opposite to the flow direction F) when viewed from the laminating direction. Accordingly, the resistance to the flow of the concave portion 422 is reduced, so that the flow of the refrigerant CM can be formed smoothly without obstructing the flow of the refrigerant CM flowing in the flow direction F.
　＜変形例５＞
　図１４は、変形例５に係る冷却部の凹部５２２の形状を示す上面図である。変形例５に係る冷却部の凹部５２２は、積層方向から見て、冷媒ＣＭの流れ方向Ｆに長尺状に延在する長方形の外形を有する。冷媒ＣＭの流れは、凹部５２２が長尺状に延在する方向に誘導されるため、流れ方向Ｆの流れをより確実に形成することができる。なお、凹部の外形は、長尺状に延在する形状を有する限りにおいて特に限定されず、例えば、楕円形であっても上記と同様の効果を得ることができる。 <Modification 5>
FIG. 14 is a top view illustrating the shape of the recess 522 of the cooling unit according to the fifth modification. The concave portion 522 of the cooling unit according to Modification Example 5 has a rectangular outer shape that extends in a long direction in the flow direction F of the coolant CM when viewed from the lamination direction. Since the flow of the refrigerant CM is guided in the direction in which the concave portion 522 extends in an elongated shape, the flow in the flow direction F can be formed more reliably. The outer shape of the concave portion is not particularly limited as long as it has a shape extending in a long shape. For example, the same effect as described above can be obtained even if the concave shape is an elliptical shape.
１０　　　電池パック、
１１　　　発電要素、
２０、２２０　冷却部、
２０Ａ　　内部空間、
２０Ｓ　　接触面、
２０ｉ　　供給口、
２０ｏ　　排出口、
２１　　　平坦部、
２２、３２２、４２２、５２２　凹部、
２３、２４　冷却板、
２５　　　筐体、
２６　　　面圧分散板、
３０　　　パックケース、
１００　　電池、
１００Ｓ　表面、
１１１　　発電要素、
１１２　　外装体、
１２０　　単セル、
１３０　　電極、
１３０ａ　正極、
１３０ｂ　負極、
１３１　　集電体、
１３１ａ　正極集電体、
１３１ｂ　負極集電体、
１３２　　電極活物質層、
１３２ａ　正極活物質層、
１３２ｂ　負極活物質層、
１３５　　双極型電極、
１４０　　電解質層、
１５０　　シール部、
１６１　　電極活物質。 10 battery pack,
11 power generation elements,
20, 220 cooling unit,
20A internal space,
20S contact surface,
20i supply port,
20o outlet,
21 flat part,
22, 322, 422, 522 recess,
23, 24 cooling plate,
25 housing,
26 surface pressure dispersion plate,
30 pack case,
100 batteries,
100S surface,
111 power generation elements,
112 exterior body,
120 single cells,
130 electrodes,
130a positive electrode,
130b negative electrode,
131 current collector,
131a positive electrode current collector,
131b negative electrode current collector,
132 electrode active material layer,
132a positive electrode active material layer,
132b negative electrode active material layer,
135 bipolar electrode,
140 electrolyte layer,
150 seal part,
161 electrode active material.

Claims (6)

  1. 　電極活物質を含む非結着体からなる電極活物質層が集電体の表面に形成されてなる電極と、電解質層とを積層した発電要素が可撓性を有する外装体に収容された電池と、
    　冷媒を保持する内部空間を形成し、前記発電要素の積層方向から前記電池の表面の少なくとも一部に対して加圧した状態で接触する接触面を備える冷却部と、を有し、
    　前記冷却部は、
    　前記接触面の面方向に沿って平坦な平坦部と、
    　前記接触面の面方向に断続的に配置され、前記平坦部の一部から前記内部空間側に向かって凹み、前記内部空間に前記冷媒の流路を区画形成する複数の凹部と、を備える、電池パック。     A battery in which a power generation element obtained by laminating an electrode in which an electrode active material layer made of a non-binder including an electrode active material is formed on the surface of a current collector and an electrolyte layer is housed in a flexible outer package When,
    A cooling unit having an internal space for holding a refrigerant, and a cooling unit having a contact surface that contacts at least a part of the surface of the battery in a pressurized direction from the stacking direction of the power generating element,
    The cooling unit includes:
    A flat portion flat along the surface direction of the contact surface,
    A plurality of recesses that are intermittently arranged in a plane direction of the contact surface, are recessed from a part of the flat portion toward the internal space, and define a flow path of the refrigerant in the internal space. Battery pack.
  2. 　前記冷却部の前記接触面の面積は、前記発電要素の積層方向を投影方向としたときの前記凹部の投影面積よりも大きい、請求項１に記載の電池パック。 2. The battery pack according to claim 1, wherein an area of the contact surface of the cooling unit is larger than a projection area of the recess when a stacking direction of the power generation elements is a projection direction.
  3. 　前記冷却部は、前記平坦部および複数の前記凹部を備える複数の冷却板を有し、
    　隣り合う前記冷却板の間には、前記内部空間が形成される、請求項１または請求項２に記載の電池パック。     The cooling unit has a plurality of cooling plates including the flat portion and a plurality of the concave portions,
    3. The battery pack according to claim 1, wherein the internal space is formed between the adjacent cooling plates. 4.
  4. 　前記冷却部は、前記電池と前記平坦部との間に配置され、前記接触面の面方向に沿って平坦な面圧分散板をさらに有する、請求項１～３のいずれか１項に記載の電池パック。 4. The cooling unit according to claim 1, wherein the cooling unit further includes a surface pressure distribution plate disposed between the battery and the flat portion and flat along a surface direction of the contact surface. Battery pack.
  5. 　前記発電要素の積層方向を投影方向としたとき、前記電極活物質層の投影面積に対する前記冷却部の前記接触面の面積は、５０％以上である、請求項１～４のいずれか１項に記載の電池パック。 The method according to any one of claims 1 to 4, wherein when a stacking direction of the power generation elements is a projection direction, an area of the contact surface of the cooling unit with respect to a projection area of the electrode active material layer is 50% or more. The battery pack as described.
  6. 　前記冷却部の前記接触面から前記電池に付与される加圧力は、２０ｋＰａ以上である、請求項１～５のいずれか１項に記載の電池パック。 The battery pack according to any one of claims 1 to 5, wherein a pressure applied to the battery from the contact surface of the cooling unit is 20 kPa or more.
PCT/JP2018/028127 2018-07-26 2018-07-26 Battery pack WO2020021683A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006012847A (en) * 2004-06-25 2006-01-12 Samsung Sdi Co Ltd Secondary battery module
JP2006253149A (en) * 2005-03-11 2006-09-21 Samsung Sdi Co Ltd Secondary battery module
JP2012015071A (en) * 2010-07-05 2012-01-19 Denso Corp Battery pack
JP2014192094A (en) * 2013-03-28 2014-10-06 Mitsubishi Electric Corp Storage battery module and manufacturing method for storage battery module
JP2017147222A (en) * 2016-02-12 2017-08-24 三洋化成工業株式会社 Lithium-ion battery

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006012847A (en) * 2004-06-25 2006-01-12 Samsung Sdi Co Ltd Secondary battery module
JP2006253149A (en) * 2005-03-11 2006-09-21 Samsung Sdi Co Ltd Secondary battery module
JP2012015071A (en) * 2010-07-05 2012-01-19 Denso Corp Battery pack
JP2014192094A (en) * 2013-03-28 2014-10-06 Mitsubishi Electric Corp Storage battery module and manufacturing method for storage battery module
JP2017147222A (en) * 2016-02-12 2017-08-24 三洋化成工業株式会社 Lithium-ion battery

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