power storage device

Abstract

A power storage device includes a plurality of power storage cells stacked in a stacking direction, and a temperature sensor that measures a temperature of at least one power storage cell among the plurality of power storage cells as a measurement target. Each of the plurality of power storage cells includes a positive electrode having a first current collector and a positive electrode active material layer provided on one face of the first current collector, a negative electrode having a second current collector and a negative electrode active material layer provided on one face of the second current collector, the negative electrode active material layer and the positive electrode active material layer being arranged so as to face each other in the stacking direction, a separator arranged between the positive electrode and the negative electrode, and a closed portion provided between the first current collector and the second current collector facing each other in the stacking direction, the closed portion enclosing the positive electrode active material layer and the negative electrode active material layer. The temperature sensor is arranged at a position inside the closed portion of the measurement target power storage cell in the stacking direction.

Description

Technical Field

[0001] This disclosure relates to energy storage devices. Background Technology

[0002] A battery is a device that generates heat due to use. From the viewpoint of battery performance and degradation, the internal temperature of the battery is adjusted to an appropriate range. Patent Document 1 discloses a bipolar secondary battery in which multiple bipolar electrodes, with a positive electrode layer formed on one side of the current collector and a negative electrode layer formed on the other side of the current collector, are connected in series with an electrolyte layer in between. In this bipolar secondary battery, a portion of each current collector has an extension that extends further outward than the positive and negative electrode layers. A sealing material that insulates the current collectors is provided on the extension. A non-sealed portion without the sealing material is formed on the extension of the current collector further outward from the sealing material. A temperature detection element is disposed in contact with this non-sealed portion.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-117626 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the battery disclosed in Patent Document 1, the sensing element for detecting the temperature of the individual cells is located on the outermost part of the current collector, beyond the sealing material surrounding the positive or negative electrode layer. Therefore, it is impossible to accurately measure the internal temperature of the individual cells. In particular, as the coating area of ​​the active material layers in the positive and negative electrode layers of the individual cells increases, the temperature difference between the end and center of the individual cells tends to increase. In other words, as the coating area increases, the difference between the external and internal temperatures of the individual cells tends to increase. Here, in Patent Document 1, since the sensing element is provided on the outside of the sealing material, this sensing element measures the external temperature of the battery. Therefore, when using the sensing element shown in Patent Document 1, for example, it is difficult to accurately measure the internal temperature of the individual cells (especially those located at the center of the battery) during use.

[0008] The purpose of this disclosure is to provide an energy storage device that can accurately measure the internal temperature of a single energy storage cell during use.

[0009] Solution for solving the problem

[0010] One aspect of the energy storage device disclosed herein includes: a plurality of energy storage cells stacked in a stacking direction; and a temperature sensor for measuring the temperature of at least one of the plurality of energy storage cells as the object of measurement. Each of the plurality of energy storage cells includes: a positive electrode having a first current collector and a positive electrode active material layer disposed on one surface of the first current collector; a negative electrode having a second current collector and a negative electrode active material layer disposed on one surface of the second current collector, arranged such that the negative electrode active material layer and the positive electrode active material layer are opposite to each other in the stacking direction; a separator disposed between the positive electrode and the negative electrode; and a sealing portion disposed between the first current collector and the second current collector opposite to each other in the stacking direction, sealing the positive electrode active material layer and the negative electrode active material layer, wherein, viewed from the stacking direction, the temperature sensor is disposed at a position inside the sealing portion of the energy storage cell to be measured.

[0011] The aforementioned energy storage device includes a temperature sensor that measures the temperature of at least one of a plurality of battery cells, with the temperature of the battery cell being measured positioned, within the stacking direction, closer to the inner side of the sealed portion of the battery cell being measured. Therefore, even when the battery cell being measured is located at the center of the energy storage device in the stacking direction, its internal temperature during use can be accurately measured using the temperature sensor.

[0012] Alternatively, the temperature sensor may be in contact with either the first or second current collector. In this case, the internal temperature of the battery cell can be precisely measured using the temperature sensor via the first or second current collector.

[0013] Alternatively, the aforementioned energy storage device may include: a laminate having a plurality of individual energy storage cells; and a sealing body extending from one end of the laminate in the lamination direction to the other, formed by integrating the sealing portions of each of the plurality of energy storage cells together, thereby sealing the laminate, with a temperature sensor disposed between one end and the other end of the laminate in the lamination direction. In this case, the internal temperature of the laminate can be precisely measured by the temperature sensor.

[0014] Alternatively, multiple battery cells may have a first battery cell and a second battery cell adjacent to each other in the stacking direction, with the first current collector of the first battery cell and the second current collector of the second battery cell adjacent to each other in the stacking direction, and a temperature sensor disposed between the first current collector of the first battery cell and the second current collector of the second battery cell. In this case, the temperature sensor can accurately measure the internal temperature of the first battery cell and the second battery cell without causing a decrease in the energy storage performance of the first battery cell and the second battery cell.

[0015] Alternatively, the aforementioned energy storage device may include: a first stack having two or more energy storage cells among a plurality of energy storage cells; a second stack adjacent to the first stack in the stacking direction, having two or more other energy storage cells among a plurality of energy storage cells; a first enclosure, which is provided by integrating the enclosure portions of the energy storage cells included in the first stack with each other, extending from one end of the first stack in the stacking direction to the other end, thereby enclosing the first stack; and a second enclosure, which is provided by integrating the enclosure portions of the energy storage cells included in the second stack with each other. The sealing portions of the individual cells are integrally formed, extending from one end of the second stacked body in the stacking direction to the other, sealing the second stacked body. The first current collector of the first energy storage cell, which is one energy storage cell included in the first stacked body, and the second current collector of the second energy storage cell, which is one energy storage cell included in the second stacked body, are adjacent in the stacking direction. A temperature sensor is disposed between the first current collector, which is the positive terminal electrode disposed at one end of the first stacked body, and the second current collector, which is the negative terminal electrode disposed at one end of the second stacked body. In this case, the internal temperature of the first stacked body can be accurately measured via the first current collector of the first energy storage cell, and / or the internal temperature of the second stacked body can be accurately measured via the second current collector of the second energy storage cell. Moreover, the temperature sensor can be disposed without compromising the sealing of the first and second stacked bodies by means of the first and second sealing portions.

[0016] Alternatively, the aforementioned energy storage device may further include: a first cooler that contacts the positive terminal electrode of the first stack; and a second cooler that contacts the negative terminal electrode of the second stack. In this case, the internal temperature of the first stack and / or the second stack can be precisely measured using a temperature sensor while maintaining the temperature of the energy storage device appropriately.

[0017] Alternatively, at least one of the first current collector of the first battery cell and the second current collector of the second battery cell may be provided with a recess for housing a temperature sensor. In this case, damage to the first current collector and / or the second current collector caused by the temperature sensor can be suppressed.

[0018] Alternatively, a first battery cell may be provided with multiple battery cells, each equipped with a temperature sensor. The temperature sensor is disposed within a space enclosed by the enclosure of the first battery cell, its first current collector, and its second current collector. In this case, the temperature sensor can accurately measure the internal temperature of the first battery cell.

[0019] Alternatively, the temperature sensor can be housed in a groove disposed in the positive electrode active material layer or in a groove disposed in the negative electrode active material layer. In this case, damage to the first battery cell caused by the temperature sensor can be suppressed.

[0020] Alternatively, the temperature sensor can be embedded in either the positive or negative electrode active material layer. In this case, movement of the temperature sensor caused by impacts applied to the energy storage device is suppressed, thus preventing friction between the first current collector and the temperature sensor, or between the second current collector and the temperature sensor. Therefore, damage to the first energy storage cell caused by the temperature sensor can be suppressed.

[0021] Alternatively, viewed from the stacking direction, the temperature sensor can be positioned in the central region of the battery cell being measured. In this case, the internal temperature of the battery cell being measured, which serves as the temperature sensor, can be measured more precisely.

[0022] Alternatively, multiple temperature sensors can be installed in a specified energy storage cell among multiple energy storage cells. These multiple temperature sensors, arranged separately from each other in the stacking direction, measure the temperature distribution of the specified energy storage cell. In this case, the internal temperature distribution of the specified energy storage cell along the plane direction orthogonal to the stacking direction can be precisely measured using multiple temperature sensors.

[0023] Alternatively, the aforementioned energy storage device may also include a flexible printed circuit board electrically connected to a temperature sensor. The temperature sensor is located at one end of the flexible printed circuit board, and the other end of the flexible printed circuit board is connected to a control circuit disposed outside the plurality of energy storage cells. In this case, the measurement results of the temperature sensor can be effectively transmitted to the control circuit located outside the laminate.

[0024] Alternatively, the flexible printed circuit board may have a voltage detection unit that contacts the current collector contained in any one of the multiple energy storage cells. In this case, the voltage of any part of the energy storage device can be measured by the temperature detection unit.

[0025] Alternatively, the flexible printed circuit board may have a conductive portion connected to the temperature sensor and an insulating portion covering the conductive portion, with the temperature sensor covered by the insulating portion. In this case, malfunction of the temperature sensor can be suppressed.

[0026] Invention Effects

[0027] According to this disclosure, an energy storage device is provided that can precisely measure the internal temperature of the energy storage cell during use. Attached Figure Description

[0028] Figure 1 This is a schematic cross-sectional view showing the energy storage device of the first embodiment.

[0029] Figure 2 (a) is a top view showing a portion of the battery stack. Figure 2(b) is a schematic cross-sectional view showing an example of a conductor.

[0030] Figure 3 (a) to (d) are cross-sectional views showing each step of the manufacturing method of the energy storage device according to the first embodiment.

[0031] Figure 4 This is a cross-sectional view showing one step of the manufacturing method of the energy storage device according to the first embodiment.

[0032] Figure 5 This is a schematic cross-sectional view showing the energy storage device of the first modified example.

[0033] Figure 6 This is a top view showing a portion of the battery stack of the first variant.

[0034] Figure 7 This is a schematic cross-sectional view showing the energy storage device of the second modified example.

[0035] Figure 8 This is a schematic cross-sectional view showing the energy storage device of the third modified example.

[0036] Figure 9 This is a schematic cross-sectional view showing the energy storage device of the fourth modified example.

[0037] Figure 10 This is a schematic cross-sectional view showing the energy storage device of the second embodiment.

[0038] Figure 11 This is a schematic cross-sectional view showing the energy storage device of the third embodiment.

[0039] Figure 12 This is a schematic cross-sectional view showing the battery stack of the third embodiment.

[0040] Figure 13 This is a schematic cross-sectional view showing a modified example of the energy storage device according to the third embodiment.

[0041] Figure 14 (a) is a schematic top view showing the main part of an example of a temperature detection unit. Figure 14 (b) is a schematic top view showing the main part of another example of a temperature detection unit. Detailed Implementation

[0042] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and repeated descriptions are omitted.

[0043] (First Embodiment)

[0044] Figure 1This is a schematic cross-sectional view showing the energy storage device of the first embodiment. Figure 1 The energy storage device 1 shown is, for example, an energy storage module used in the batteries of various vehicles such as forklifts, hybrid vehicles, and electric vehicles. Energy storage device 1 is, for example, a nickel-metal hydride secondary battery or a lithium-ion secondary battery. Energy storage device 1 can also be an electric double-layer capacitor or an all-solid-state battery. In the first embodiment, the case where energy storage device 1 is a lithium-ion secondary battery is illustrated.

[0045] The energy storage device 1 includes a battery stack 5 (stack) formed by stacking multiple energy storage cells 2 in a stacking direction, and a temperature detection unit 100. For example... Figure 1 As shown, each battery cell 2 includes a positive electrode 11, a negative electrode 12, a separator 13, and a sealing portion 14. The positive electrode 11 includes a first current collector 20 and a positive active material layer 22 disposed on one surface 20a of the first current collector 20. The positive electrode 11 is, for example, a rectangular electrode viewed from the stacking direction. The negative electrode 12 includes a second current collector 21 and a negative active material layer 23 disposed on one surface 21a of the second current collector 21. The negative electrode 12 is, for example, a rectangular electrode viewed from the stacking direction. The negative electrode 12 is arranged such that the negative active material layer 23 is opposite to the positive active material layer 22 in the stacking direction. In the first embodiment, both the positive active material layer 22 and the negative active material layer 23 are rectangular in shape viewed from the stacking direction. The negative active material layer 23 is formed to be slightly larger than the positive active material layer 22. From the perspective of the stacking direction, the entire formation region of the positive electrode active material layer 22 is located within the formation region of the negative electrode active material layer 23.

[0046] The first current collector 20 has another side 20b, which is the side opposite to one side 20a. No positive electrode active material layer 22 is formed on the other side 20b. The second current collector 21 has another side 21b, which is the side opposite to one side 21a. No negative electrode active material layer 23 is formed on the other side 21b. Battery stack 5 is constructed by stacking the battery cells 2 such that the other side 20b of the first current collector 20 and the other side 21b of the second current collector 21 are in contact with each other. Thus, multiple battery cells 2 are electrically connected in series. In the battery stack 5, among adjacent battery cells 2, 2 along the stacking direction, the first current collector 20 of one battery cell 2 is in contact with the second current collector 21 of the other battery cell 2. In the battery stack 5, a pseudo-bipolar electrode 10 is formed, which uses the first current collector 20 and the second current collector 21 as electrode bodies. That is, a bipolar electrode 10 includes: a first current collector 20, a second current collector 21, a positive electrode active material layer 22, and a negative electrode active material layer 23. The first current collector 20 is disposed at one end of the battery stack 5 in the stacking direction as a terminal electrode. The second current collector 21 is disposed at the other end of the battery stack 5 in the stacking direction as a terminal electrode.

[0047] The first current collector 20 and the second current collector 21 (hereinafter also referred to as "current collectors") are each chemically inert conductors used to continuously allow current to flow through the positive electrode active material layer 22 and the negative electrode active material layer 23 during the discharge or charging of the lithium-ion secondary battery. Examples of materials constituting the current collectors include metallic materials, conductive resin materials, and conductive inorganic materials. Examples of conductive resin materials include resins in which conductive fillers are added to conductive or non-conductive polymer materials as needed. The current collector may also have multiple layers comprising one or more layers, wherein the one or more layers include the aforementioned metallic materials or conductive resin materials. A coating layer may be formed on the surface of the current collector by known methods such as plating or spraying. The current collector may be formed in the form of a plate, foil, sheet, film, mesh, etc. When the current collector is made of a metal foil, aluminum foil, copper foil, nickel foil, titanium foil, or stainless steel foil may be used, for example. The current collector can also be an alloy foil or clad foil of the aforementioned metals. In the case of a foil-shaped current collector, the thickness of the current collector can be in the range of 1 μm to 100 μm. In the first embodiment, the first current collector 20 is an aluminum foil, and the second current collector 21 is a copper foil.

[0048] The positive electrode active material layer 22 contains a positive electrode active material capable of absorbing and releasing charge carriers such as lithium ions. As the positive electrode active material, any material suitable for use as a positive electrode active material in lithium-ion secondary batteries, such as lithium composite metal oxides with a layered rock salt structure, metal oxides with a spinel structure, or polyanionic compounds, can be used. Alternatively, two or more positive electrode active materials can be used simultaneously. In the first embodiment, the positive electrode active material layer 22 contains olivine-type lithium iron phosphate (LiFePO4) as a composite oxide.

[0049] The negative electrode active material layer 23 can be any element, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions, and is not particularly limited in its use. Examples of negative electrode active materials include Li, carbon, metal compounds, elements or compounds capable of alloying with lithium, etc. Examples of carbon include natural black lead, artificial black lead, hard carbon (difficult to blacken) or soft carbon (easily blacken). Examples of artificial black lead include highly oriented graphite, mesophase carbon microspheres, etc. Examples of elements capable of alloying with lithium include silicon and tin. In this embodiment, the negative electrode active material layer 23 contains black lead as a carbon-based material.

[0050] The positive electrode active material layer 22 and the negative electrode active material layer 23 (hereinafter also referred to as "active material layers") may each contain conductive additives, binders, electrolytes (polymer matrix, ion-conducting polymer, electrolyte solution, etc.), and electrolyte support salts (lithium salts) to improve ion conductivity, as needed. The components contained in the active material layer, their mixing ratio, and the thickness of the active material layer are not particularly limited and can be appropriately referenced to previously known understandings regarding lithium-ion secondary batteries. The thickness of the active material layer is, for example, 2–150 μm. To form the active material layer on the surface of the current collector, previously known methods such as roller coating can be used. To improve the thermal stability of the positive electrode 11 or the negative electrode 12, a heat-resistant layer may be provided on the surface of the current collector (single-sided or double-sided) or the surface of the active material layer. The heat-resistant layer may contain, for example, inorganic particles and binders, and may also contain additives such as thickeners.

[0051] Conductive additives are added to improve the conductivity of the positive electrode 11 or the negative electrode 12. Examples of conductive additives include acetylene black, carbon black, and graphite. The binder serves to bind the active material or conductive additive to the surface of the current collector.

[0052] The separator 13 is a component disposed between the positive electrode 11 and the negative electrode 12, allowing charge carriers such as lithium ions to pass through. The separator 13 also prevents short circuits caused by contact between the two electrodes by isolating the positive electrode 11 and the negative electrode 12. The separator 13 is, for example, a porous sheet or nonwoven fabric containing a polymer that absorbs and retains the electrolyte. Examples of materials constituting the separator 13 include polypropylene, polyethylene, polyolefin, and polyester. The separator 13 can have a single-layer or multi-layer structure. A multi-layer structure may include, for example, an adhesive layer and a ceramic layer as a heat-resistant layer. The separator 13 may be impregnated with an electrolyte, or it may be composed of an electrolyte such as a polymeric electrolyte or an inorganic electrolyte. In this embodiment, the separator 13 has: a substrate layer 13a; a first adhesive layer 13b disposed on a first surface 13aa of the substrate layer 13a; and a second adhesive layer 13c disposed on a second surface 13ab of the substrate layer 13a.

[0053] Examples of electrolytes impregnated in the separator 13 include liquid electrolytes (electrolytes) containing a non-aqueous solvent and electrolyte salts dissolved in the non-aqueous solvent, or polymeric gel electrolytes containing electrolytes retained in a polymer matrix. The electrolyte is contained in the space S of the energy storage device 1.

[0054] When the separator 13 is impregnated with an electrolyte, known lithium salts such as LiClO4, LiAsF6, LiPF6, LiBF4, LiCF3SO3, LiN(FSO2)2, and LiN(CF3SO2)2 can be used as the electrolyte salt. Furthermore, known solvents such as cyclic carbonates, cyclic esters, chain carbonates, chain esters, and ethers can be used as non-aqueous solvents. In addition, combinations of two or more of these known solvent materials can be used.

[0055] The first adhesive layer 13b is bonded to the positive electrode active material layer 22. The second adhesive layer 13c is bonded to the negative electrode active material layer 23. The first adhesive layer 13b may also be disposed on the entire surface of the first surface 13aa of the substrate layer 13a. The second adhesive layer 13c may also be disposed on the entire surface of the second surface 13ab of the substrate layer 13a. The first adhesive layer 13b and the second adhesive layer 13c may each contain, for example, thermosetting resins such as epoxy resin, polyimide resin, and phenolic resin, and may also contain an adhesive that cures by reacting with water such as electrolyte.

[0056] The sealing portion 14 is a resin component that seals the space S between the positive electrode 11 and the negative electrode 12 and has electrical insulation properties. The sealing portion 14 seals the space S in a manner that surrounds the positive electrode active material layer 22 and the negative electrode active material layer 23. The sealing portion 14 is composed of a rectangular frame-shaped resin frame 25 viewed from the stacking direction, which is fused to the edge 20e of the first current collector 20 and the edge 21e of the second current collector 21. The sealing portion 14 is formed in a frame shape in a manner that surrounds the positive electrode active material and the negative electrode active material contained in the battery stack 5 viewed from the stacking direction. In the first embodiment, a sealing body 14a is formed, which is provided by integrating a plurality of sealing portions 14 arranged in the stacking direction of the battery stack 5, extending from one end of the battery stack 5 in the stacking direction to the other end. For example, the sealing portion 14 has a joining portion that engages with the current collector and an extending portion that extends outward compared to the edge of the current collector. For example, multiple closures 14 are integrated by fusing the protruding portions of adjacent closures 14 to each other. The closure 14a, viewed from the stacking direction, is a component that encloses the battery stack 5 by surrounding and integrating multiple battery cells 2, and has a sidewall portion. This sidewall portion extends in the stacking direction from a first current collector 20 disposed at one end of the battery stack 5 to a second current collector 21 disposed at the other end of the stacking direction. Through the sidewall portion of the closure 14a, the sides of the battery stack 5 along the stacking direction are closed, and adjacent battery cells 2 in the stacking direction are also closed. Examples of resin materials constituting the closure 14 include polyethylene (PE), polystyrene, ABS resin, modified polypropylene (modified PP), and acrylonitrile styrene (AS) resin.

[0057] In the first embodiment, the edge 13e of the separator 13 is bonded to a surface 20a of the first current collector 20 via a first adhesive layer 13b. The surface 20a of the first current collector 20 includes a coated area with a positive electrode active material layer 22 and an uncoated area without the positive electrode active material layer 22. The uncoated area is disposed around the coated area. The separator 13 is bonded to this uncoated area. The sealing portion 14 is bonded to a second adhesive layer 13c at the edge 13e of the separator 13. The edge 13e of the separator 13 is fixed by being sandwiched between the surface 20a of the first current collector 20 and the sealing portion 14.

[0058] Figure 2 (a) is a top view showing a portion of the battery stack. Figure 1 and Figure 2The temperature sensing unit 100 shown in (a) is a device for detecting the temperature of a single cell 2 within the battery stack 5. The temperature sensing unit 100 is configured to contact the target single cell 2 among the stacked multiple single cells 2. In the first embodiment, at least one single cell 2 (the first single cell) among the multiple single cells 2 included in the battery stack 5 contains the temperature sensing unit 100. This temperature sensing unit 100 is disposed in a space S enclosed by the sealing portion 14, the first current collector 20 of the positive electrode 11, and the second current collector 21 of the negative electrode 12. Furthermore, from the viewpoint of suppressing capacity degradation of the negative electrode 12, the temperature sensing unit 100 is not embedded in the negative electrode active material layer 23 of the negative electrode 12, but rather embedded in the positive electrode active material layer 22 of the positive electrode 11.

[0059] The temperature detection unit 100 includes a temperature sensor 101. The temperature sensor 101 is an element that detects the temperature within the battery cell 2 and is embedded in the positive electrode active material layer 22. In the first embodiment, the temperature sensor 101 detects the temperature within the positive electrode active material layer 22. Viewed from the stacking direction, the temperature sensor 101 is positioned inwards from the sealing portion 14 of the battery cell 2. In the first embodiment, the temperature sensor 101 is positioned in the central region of the battery stack 5 viewed from the stacking direction, and is positioned between one end and the other end of the battery stack 5 in the stacking direction. This central region is, for example, any of the following: the center or vicinity of the positive electrode active material layer 22 and / or the negative electrode active material layer 23; the region overlapping with the positive electrode active material layer 22 and / or the negative electrode active material layer 23 viewed from the stacking direction; or a portion of the region surrounded by the resin frame 25 viewed from the stacking direction. This part can be, for example, equivalent to the following diagram: its center, viewed from the stacking direction, is the same as the center of the resin frame 25, and the length of the diagonal (or the length of the diameter) of the aforementioned part is half the length of the diagonal (or the length of the diameter) of the inner frame of the resin frame 25. In the first embodiment, the temperature sensor 101 is disposed at or near the center of the positive electrode active material layer 22. The temperature sensor 101 is, for example, a thermocouple, a thermistor, etc. When the temperature sensor 101 is a thermocouple, the temperature sensor 101 corresponds to the part where the two metal wires are in contact. The thermocouple is a known thermocouple, such as a nickel-aluminum-nickel thermocouple, a nickel-constantan thermocouple, a copper-constantan thermocouple, etc. The thermistor is, for example, an NTC thermistor, a PTC thermistor, etc. As the thermistor, a flexible thin film thermistor can also be used. The thickness of such a flexible film thermistor (hereinafter also referred to as "flexible thermistor") is, for example, 0.1 μm or more and 1 μm or less. By using this flexible thermistor, the maximum thickness of the temperature sensing section 100 can be set to, for example, 100 μm or less. This effectively suppresses the capacity reduction of the battery cell 2 caused by the temperature sensing section 100. From the viewpoint of preventing reaction with the electrolyte or the like housed in the space S, the temperature sensor 101 is, for example, covered with an insulating resin such as polyimide.

[0060] A wire 102 is connected to the temperature sensor 101 to a control device (control circuit) located outside the energy storage device 1 (battery stack 5). The temperature sensor 101 is located at one end of the wire 102. The other end of the wire 102 extends to the outside of the energy storage device 1 and is connected to a control device (not shown) that monitors the temperature of the energy storage device 1. If the temperature sensor 101 is a thermocouple, the wire 102 contains two types of metal wires used to form a thermocouple. Viewed in the stacking direction, the wire 102 extends from the interior of the energy storage device 1 where the temperature sensor 101 is located to the exterior of the energy storage device 1, which is located further out than the enclosure 14. Inside the energy storage device 1, a portion of the wire 102 is embedded in the positive electrode active material layer 22, and another portion of the wire 102 is embedded in the enclosure 14. From the viewpoint of preventing reaction with the electrolyte or the like contained in the space S, the wire 102 is covered, for example, with a sheath formed of insulating resin. Viewed from the stacking direction, a portion of the conductor 102 is located within the area surrounded by the enclosure 14, while another portion of the conductor 102 is located outside that area.

[0061] Figure 2 (b) is a schematic cross-sectional view showing an example of the conductor in this embodiment. Figure 2 As shown in (b), when a thermistor or similar sensor is used as the temperature sensor 101, a flexible thin substrate, such as an FPC (flexible printed circuit board), is used as the wire 102. The wire 102 formed by the FPC includes a conductor foil 102a (conductive portion) and a thin film base film 102b (insulating portion) made of polyimide or the like. The wire 102 is formed, for example, in the shape of a long strip when viewed from above. The conductor foil 102a is connected to the temperature sensor 101 and is attached to the base film 102b. From the viewpoint of preventing reaction with the electrolyte or the like contained in the space S, the conductor foil 102a is covered by the base film 102b. From the viewpoint of suppressing the capacity drop of the battery cell 2 and the poor sealing of the sealing portion 14 caused by the wire 102, the thickness of the wire 102 is set to, for example, 10 μm or more and less than 100 μm.

[0062] The thermistor and the conductor foil 102a, and the conductor foil 102a and the external device, are electrically connected, for example, through openings formed in the base film 102b. The thermistor can be fixed to the conductor foil 102a, for example, by solder, by a conductive adhesive, or by welding. When the temperature sensor 101 is a flexible thermistor, it can also be covered by the base film 102b along with the conductor foil 102a. In this case, the flexible thermistor may not be covered by any material other than the base film 102b.

[0063] Figure 3 (a)~(d) and Figure 4 This is a cross-sectional view showing each step of the manufacturing method of the energy storage device according to the first embodiment. The energy storage device 1 can be manufactured, for example, by the following method.

[0064] (Preparation of the positive electrode unit)

[0065] First, such as Figure 3 As shown in (a), a positive electrode unit U1 is prepared. The positive electrode unit U1 has a positive electrode 11 (first electrode), which has a first current collector 20 and a positive electrode active material layer 22 (first active material layer) disposed on a surface 20a of the first current collector 20. In the first embodiment, the positive electrode unit U1 has a separator 13 disposed on a surface 20a of the first current collector 20. The separator 13 is configured to cover the positive electrode active material layer 22. The separator 13 has a substrate layer 13a; a first adhesive layer 13b disposed on a first surface 13aa of the substrate layer 13a; and a second adhesive layer 13c disposed on a second surface 13ab of the substrate layer 13a. The first adhesive layer 13b at the edge 13e of the separator 13 is configured to face a surface 20a of the first current collector 20. In this process, the first adhesive layer 13b at the edge 13e of the spacer 13 can also be bonded to a surface 20a of the first current collector 20. When the first adhesive layer 13b and the second adhesive layer 13c of the spacer 13 contain a thermosetting adhesive, the thermosetting adhesive has adhesive properties even in its uncured state. Therefore, the edge 13e of the spacer 13 is bonded and fixed to a surface 20a of the first current collector 20 via the adhesive layers.

[0066] A wire 102 and a temperature sensor 101 are embedded in the positive electrode active material layer 22 of a portion of the positive electrode unit U1 (see reference). Figure 3 (c) Alternatively, after placing the temperature sensor 101 and the wire 102 onto one surface 20a of the first current collector 20, a positive electrode active material layer 22 may be formed on the temperature sensor 101 and the wire 102, thereby arranging the temperature sensor 101 and the wire 102 to be embedded in the positive electrode active material layer 22. Alternatively, after forming the positive electrode active material layer 22 on one surface 20a of the first current collector 20, the temperature sensor 101 and the wire 102 may be disposed on the positive electrode active material layer 22, and then an isolator 13 may be disposed on the temperature sensor 101 and the wire 102. Furthermore, the temperature sensor 101 and the wire 102 may be embedded in the positive electrode active material layer 22 when the positive electrode active material layer 22 is formed on one surface 20a of the first current collector 20.

[0067] (Preparation of the negative electrode unit)

[0068] like Figure 3As shown in (b), a negative electrode unit U2 is prepared. The negative electrode unit U2 has: a negative electrode 12 (a second electrode having a polarity different from that of the first electrode), which has a second current collector 21 and a negative electrode active material layer 23 (second active material layer) disposed on a surface 21a of the second current collector 21; and a resin frame 25, which is fused to the edge 21e of the second current collector 21.

[0069] In this embodiment, during the preparation step of the positive electrode unit U1, the positive electrode unit U1 is prepared by disposing of an insulator 13 on the positive electrode active material layer 22 formed on the first current collector 20. However, the method of disposing of the insulator 13 is not limited to this. The insulator 13 may also not be provided in the positive electrode unit U1. For example, during the preparation step of the negative electrode unit U2, the insulator 13 may be disposed on the negative electrode active material layer 23 formed on the second current collector 21 to prepare the negative electrode unit U2. Alternatively, the insulator 13 may not be provided in either the preparation step of the positive electrode unit U1 or the preparation step of the negative electrode unit U2. For example, during the stacking step of the positive electrode unit U1 and the negative electrode unit U2, which will be described later, the insulator 13 may be disposed between the positive electrode unit U1 and the negative electrode unit U2.

[0070] (Stacking of positive and negative electrode units)

[0071] Next, as Figure 3 As shown in (c), positive electrode units U1 and negative electrode units U2 are alternately stacked. At this time, the negative electrode active material layer 23 faces the positive electrode active material layer 22 across the separator 13. The edge 13e of the separator 13 is disposed between one surface 20a of the first current collector 20 and the resin frame 25. The first adhesive layer 13b at the edge 13e of the separator 13 faces one surface 20a of the first current collector 20. Furthermore, other negative electrode units U2 are stacked on the positive electrode unit U1 in such a way that the other surface 20b of the first current collector 20 of the positive electrode unit U1 stacked on the negative electrode unit U2 contacts the other surface 21b of the second current collector 21 of another negative electrode unit U2. The second adhesive layer 13c at the edge 13e of the separator 13 faces the resin frame 25. A plurality of resin frames 25 are arranged separately from each other in the stacking direction of the positive electrode units U1 and the negative electrode units U2.

[0072] (Form of the closed section)

[0073] Next, as Figure 3As shown in (d), the resin frame 25, sandwiched between the first current collector 20 of the positive electrode unit U1 and the second current collector 21 of the negative electrode unit U2, is fused to the edge 20e of the first current collector 20. This forms a resin sealing portion 14 that encloses the space S between the positive electrode 11 and the negative electrode 12. At this time, a portion of the wire 102 connected to the temperature sensing unit 100 is embedded in the resin frame 25. Alternatively, adjacent resin frames 25 in the stacking direction of the positive electrode unit U1 and the negative electrode unit U2 can be fused together. For example, when fusing the resin frames 25 together, adjacent resin frames 25 are fused together by pressing a hot plate against the outer peripheral surface 25s of each resin frame 25.

[0074] (Initial charging and discharging of the energy storage device)

[0075] Next, as Figure 4 As shown, the initial charge-discharge (activation process) of the energy storage device 1, which includes a positive electrode 11, a negative electrode 12, and a separator 13, is performed. In the first embodiment, the initial charge-discharge is performed with the positive electrode 11, the negative electrode 12, and the separator 13 constrained in the stacking direction. In the stacking direction, the energy storage device 1 is constrained by clamping the energy storage device 1 between a pair of constraining members 30. A positive electrode current collector 40 electrically connected to the first current collector 20 is disposed between one constraining member 30 and a first current collector 20 disposed at one end in the stacking direction. An insulating plate 41 is disposed between the positive electrode current collector 40 and one constraining member 30. A negative electrode current collector 50 electrically connected to the second current collector 21 is disposed between the other constraining member 30 and a second current collector 21 disposed at the other end in the stacking direction. An insulating plate 51 is disposed between the negative electrode current collector 50 and the other constraining member 30.

[0076] The initial charging and discharging of the energy storage device 1 is carried out, for example, by placing the energy storage device 1, which is constrained by a pair of constraint members 30, in a constant temperature bath and connecting the power supply wiring to the positive current collector 40 and the negative current collector 50.

[0077] After the activation process, the constraints of the pair of restraining members 30 are released, and the energy storage device 1 is removed. In this way, the energy storage device 1 can be manufactured. The wire 102 leading out from the energy storage device 1 is connected to an external control device or the like for monitoring the temperature of the energy storage device 1.

[0078] The effects of the energy storage device 1 according to the first embodiment will now be explained. For example, when the coating area of ​​the active material layer is large when viewed from the stacking direction, it is difficult to accurately measure the temperature difference within the active material. In this regard, in the first embodiment, the temperature sensor 101 is disposed at a position closer to the inside of the enclosure 14a when viewed from the stacking direction, and is disposed inside the specified energy storage cell 2 included in the battery stack 5. Therefore, the temperature sensor 101 can accurately measure the internal temperature of the specified energy storage cell 2 when the energy storage device 1 is in use. Moreover, the temperature sensor 101 is disposed between one end and the other end of the battery stack 5 in the stacking direction. Therefore, for example, the internal temperature of the energy storage cell 2 located on the center side of the battery stack 5 in the stacking direction can also be accurately measured when in use. Therefore, according to the first embodiment, it is possible to quickly detect whether an abnormal temperature has occurred inside the energy storage device 1.

[0079] In the first embodiment, the energy storage device 1 includes a single energy storage cell 2, which has: a positive electrode 11 having a first current collector 20 and a positive active material layer 22 disposed on a surface 20a of the first current collector 20; a negative electrode 12 having a second current collector 21 and a negative active material layer 23 disposed on a surface 21a of the second current collector 21, with the negative active material layer 23 and the positive active material layer 22 arranged opposite each other in the stacking direction; and a separator 13 disposed between the positive electrode 11 and the negative electrode 12. A temperature sensor 101 is disposed within a space S enclosed by the enclosure 14, the first current collector 20, and the second current collector 21. Therefore, the temperature sensor 101 can accurately measure the internal temperature of the energy storage cell 2, which is the object of measurement by the temperature sensor 101.

[0080] In the first embodiment, the temperature sensor 101 is embedded in the positive electrode active material layer 22. Therefore, movement of the temperature sensor 101 caused by impacts or the like applied to the energy storage device 1 is suppressed, and thus, the temperature sensor 101 is less likely to come into contact with the first current collector 20. Therefore, damage to the first current collector 20 caused by the temperature sensor 101 can be suppressed.

[0081] In the first embodiment, at least a portion of the temperature sensor 101 is disposed in the central region of the battery stack 5 as viewed from the stacking direction. Therefore, the internal temperature of the battery cell 2, which is the object of measurement of the temperature sensor 101, can be measured more precisely.

[0082] In the first embodiment, the energy storage device 1 includes a wire 102 formed of an FPC electrically connected to a temperature sensor 101. The temperature sensor 101 is disposed at one end of the wire 102, and the other end of the wire 102 is connected to a control circuit disposed outside the battery stack 5. Therefore, the measurement result of the temperature sensor 101 can be transmitted to the control circuit located outside the battery stack 5.

[0083] In the first embodiment, the wire 102 includes: a conductor foil 102a, which is a conductive portion connected to the temperature sensor 101; and a base film 102b, which is an insulating portion covering the conductor foil 102a, and the temperature sensor 101 is covered by the base film 102b. Therefore, malfunction of the temperature sensor 101 can be suppressed.

[0084] Hereinafter, variations of the first embodiment described above will be described. In the following variations, descriptions that are repeated in the first embodiment described above will be omitted. Therefore, the following mainly describes the differences from the first embodiment described above.

[0085] Figure 5 This is a schematic cross-sectional view showing the energy storage device of the first modified example. Figure 6 This is a top view showing a portion of the battery stack in the first modified example. (See attached image.) Figure 5 and Figure 6 As shown, the energy storage device 1A of the first modification includes a plurality of energy storage cells 2A. A groove 22a extending in a direction intersecting the stacking direction (hereinafter referred to as the "intersecting direction") is provided on the positive electrode active material layer 22A of the energy storage cell 2A. The groove 22a extends from one end of the positive electrode active material layer 22A in the intersecting direction to the other end. The bottom surface of the groove 22a is formed by a first current collector 20. Therefore, the positive electrode active material layer 22A is cut into two parts 22b and 22c by the groove 22a. In the first modification, the groove 22a overlaps with the center of the first current collector 20 when viewed from the stacking direction, but is not limited thereto. When the positive electrode active material layer 22A has a plurality of grooves 22a, any one groove 22a may overlap with the center of the first current collector, or none of the grooves 22a may overlap with the center.

[0086] Similarly, a groove 23a extending in the intersecting direction is provided in the negative electrode active material layer 23A. The groove 23a extends from one end of the negative electrode active material layer 23A in the intersecting direction to the other end. The bottom surface of the groove 23a is formed by the second current collector 21. Therefore, the negative electrode active material layer 23A is cut into two parts by the groove 23a. The groove 23a overlaps with the groove 22a in the stacking direction. In the first modified example, the width of the groove 23a is less than or equal to the width of the groove 22a.

[0087] In the first modification, the temperature sensing unit 100 is housed in the groove 22a. The temperature sensing unit 100 is in contact with a portion of the groove 22a defined in the center of the positive electrode active material layer 22A. The temperature sensor 101 is in contact with the first current collector 20 within the groove 22a. In the first modification, a portion of the wire 102 is in contact with a portion of the groove 22a defined in the positive electrode active material layer 22A. Viewed from the stacking direction, the wire 102 may also be connected to both portions 22b and 22c of the positive electrode active material layer 22A and the first current collector 20. Furthermore, the central portion of the positive electrode active material layer 22A corresponds, for example, to the portion that overlaps with the central region of the battery stack 5 in the stacking direction.

[0088] A metal layer 15 may also be formed on the surface (outer peripheral surface) of the sealing portion 14. The metal layer 15 extends in the stacking direction from a first current collector 20 disposed at one end of the stacking direction of the battery stack 5 to a second current collector 21 disposed at the other end of the stacking direction. The metal layer 15 may also be attached to the surface of the sealing portion 14 via an adhesive layer 16, for example. Alternatively, the metal layer 15 may be formed directly on the surface of the sealing portion 14 without the adhesive layer 16. In this case, the metal layer 15 may be formed, for example, by vapor deposition, or by fusing a metal foil to the surface of the sealing portion 14. Furthermore, an insulating layer 17 may be further formed on the surface of the metal layer 15. The insulating layer 17 may be formed, for example, from an insulating resin.

[0089] In the first variation described above, the same effect is achieved as in the first embodiment described above. Furthermore, a portion of the groove 22a may overlap with the negative electrode active material layer 23A, but the groove 23a does not overlap with the positive electrode active material layer 22A.

[0090] Figure 7 This is a schematic cross-sectional view showing the energy storage device of the second modified example. Figure 7 As shown, the energy storage device 1B of the second modification includes a plurality of energy storage cells 2 and one or more energy storage cells 2B. The positive electrode active material layer 22B of the energy storage cell 2B has a recess 22d that is recessed toward the first current collector 20 in the stacking direction. The recess 22d is defined by the positive electrode active material layer 22B. Therefore, both sides and the bottom surface of the recess 22d are formed by the positive electrode active material layer 22B. The recess 22d extends from one end of the positive electrode active material layer 22B in the intersecting direction, for example, but is not limited thereto. The recess 22d overlaps with the negative electrode active material layer 23 in the stacking direction. Viewed from the intersecting direction, the recess 22d has a generally rectangular shape. The depth of the recess 22d in the stacking direction is, for example, more than 50% and less than 90% of the thickness of the positive electrode active material layer 22B in the stacking direction.

[0091] In the second variation, the temperature sensing unit 100 included in the battery cell 2B is located between the positive electrode 11B and the negative electrode 12 in the stacking direction. Furthermore, the temperature sensing unit 100 is housed in the recess 22d. The temperature sensing unit 100 is in contact with the portion of the recess 22d defined in the center of the positive electrode active material layer 22B. Viewed from the stacking direction, the wire 102 can also contact both sides of the recess 22d.

[0092] In the second variation described above, the same effect is achieved as in the first embodiment. Furthermore, since the temperature detection unit 100 is in direct contact with the positive electrode active material layer 22B, the temperature of the positive electrode active material layer 22B can be precisely measured.

[0093] Figure 8 This is a schematic cross-sectional view showing the energy storage device of the third modified example. Figure 8 As shown, the energy storage device 1C of the third modification includes a plurality of energy storage cells 2 and one or more energy storage cells 2C. The surface of the second current collector 21 included in the energy storage cell 2C is formed of copper. In addition, the energy storage cell 2C has a constantan wire 103. One end of the constantan wire 103 is embedded in the positive electrode active material layer 22 and is in contact with the surface of the second current collector 21. In the third modification, a thermocouple is formed by the surface of the second current collector 21 and the constantan wire 103. In the third modification, the temperature detection unit 100A (and temperature sensor) included in the energy storage cell 2C is formed by the surface of the second current collector 21 and one end of the constantan wire 103.

[0094] In the third variation described above, the same effect is achieved as in the first embodiment. Furthermore, since the temperature sensing section 100A is formed from the surface of the second current collector 21 and the constantan wire 103, the configuration of the temperature sensing section 100A in the battery cell 2C can be simplified. Additionally, the number of take-out wirings from the battery storage device 1C can be reduced.

[0095] Figure 9 This is a schematic cross-sectional view showing the energy storage device of the fourth modified example. Figure 9As shown, in the fourth modification, the temperature sensing unit 100 of the energy storage device 1D is disposed in the central region of the battery stack 5 when viewed from the stacking direction, and is disposed between two adjacent energy storage cells 2,2 along the stacking direction. More specifically, the temperature sensing unit 100 is sandwiched between the central portion of the second current collector 21 of one energy storage cell 2 (the first energy storage cell) and the central portion of the first current collector 20 of the other energy storage cell 2 (the second energy storage cell). The temperature sensing unit 100 can contact the second current collector 21 of one energy storage cell 2 and the first current collector 20 of the other energy storage cell 2. In the stacking direction, the portion of the second current collector 21 included in one energy storage cell 2 that overlaps with the temperature sensing unit 100 is recessed toward the negative electrode active material layer 23. In the fourth modification, in the stacking direction, at least the portion of the second current collector 21 of one energy storage cell 2 that overlaps with the temperature sensor 101 is recessed toward the negative electrode active material layer 23. The temperature sensor 101 is housed in the recess of the second current collector 21. Furthermore, the central portions of the first current collector 20 and the second current collector 21 each correspond to portions that overlap with the central region of the battery stack 5 in the stacking direction.

[0096] In the fourth variation described above, the same effect is achieved as in the first embodiment. Furthermore, it can suppress damage to the second current collector 21 of one battery cell 2 and the first current collector 20 of the other battery cell 2 caused by the temperature sensor 101.

[0097] (Second Implementation)

[0098] The energy storage device according to the second embodiment will be described below. In the second embodiment described below, the descriptions that are repeated with the first embodiment and its modifications are omitted. Therefore, the following mainly describes the differences from the first embodiment and its modifications.

[0099] Figure 10 This is a schematic cross-sectional view showing the energy storage device of the second embodiment. Figure 10 The energy storage device 1E shown includes: a battery stack 5A (laminated structure), a positive current collector 61, a negative current collector 62, a enclosure 63, and a temperature sensing unit 100. The battery stack 5A includes: multiple bipolar electrodes 10A, multiple separators 13, a positive terminal electrode 64, and a negative terminal electrode 65. In the battery stack 5A, the bipolar electrodes 10A and separators 13 are alternately stacked. Therefore, one separator 13 is disposed between two adjacent bipolar electrodes 10A, 10A (the first bipolar electrode and the second bipolar electrode) in the stacking direction.

[0100] Each of the multiple bipolar electrodes 10A has: a current collector 71; a positive active material layer 22C disposed on one surface 71a of the current collector 71; and a negative active material layer 23B disposed on the other surface 71b of the current collector 71. The current collector 71 is, for example, a metal foil such as nickel foil, titanium foil, or stainless steel foil. The surface of the current collector 71 may also be plated. The thickness of the current collector 71 is, for example, in the range of 1 μm to 100 μm. The positive active material layer 22C and the negative active material layer 23B are respectively identical to the positive active material layer 22 and the negative active material layer 23 of the first embodiment described above. The negative active material layer 23B is configured to face the positive active material layer 22C in the stacking direction. Viewed from the stacking direction, the negative active material layer 23B is formed to be one size larger than the positive active material layer 22C.

[0101] A positive terminal electrode 64 is disposed at one end of the battery stack 5A in the stacking direction, and a negative terminal electrode 65 is disposed at the other end of the battery stack 5A in the stacking direction. The positive terminal electrode 64 and the negative terminal electrode 65 are each stacked on the bipolar electrode 10A with a separator 13 in between. The positive terminal electrode 64 has a current collector 71 and a positive active material layer 22C. A negative active material layer 23B is not disposed on the positive terminal electrode 64. The negative terminal electrode 65 has a current collector 71 and a negative active material layer 23B. A positive active material layer 22C is not disposed on the negative terminal electrode 65.

[0102] In the second embodiment, the plurality of battery cells 2D include two adjacent bipolar electrodes 10A in the stacking direction and a separator 13 located between the two bipolar electrodes 10A. More specifically, the battery cell 2D includes: a current collector 71 and a positive active material layer 22C included in one bipolar electrode 10A; a separator 13; and a current collector 71 and a negative active material layer 23B included in the other bipolar electrode 10A. Therefore, in the second embodiment, two adjacent battery cells 2D in the stacking direction among the plurality of battery cells 2D included in the battery stack 5A share one bipolar electrode 10A. For example, the current collector 71 and the positive active material layer 22C of one bipolar electrode 10A are included in one battery cell 2D, and the current collector 71 and the negative active material layer 23B are included in the other battery cell 2D. Furthermore, the energy storage cell 2E in the second embodiment includes: a current collector 71A and a negative active material layer 23B, which are closest to the bipolar electrode 10A in the stacking direction to the positive terminal electrode 64; an insulator 13; and a positive terminal electrode 64. The energy storage cell 2F in the second embodiment includes: a current collector 71A and a positive active material layer 22C, which are closest to the bipolar electrode 10A in the stacking direction to the negative terminal electrode 65; an insulator 13; and a negative terminal electrode 65.

[0103] The positive current collector 61 is a conductive component in contact with the battery stack 5A, and is plate-shaped. The positive current collector 61 is in contact with the positive terminal electrode 64. The negative current collector 62 is a conductive component in contact with the battery stack 5A, and is plate-shaped. The negative current collector 62 is in contact with the negative terminal electrode 65.

[0104] The enclosure 63 is an insulating member that holds the plurality of bipolar electrodes 10A, the plurality of separators 13, the positive terminal electrode 64, and the negative terminal electrode 65 contained in the battery stack 5A. The enclosure 63 extends from one end of the battery stack 5A in the stacking direction to the other end, sealing the battery stack 5A. The enclosure 63 has a plurality of sealing portions 66 and an outermost insulating membrane 67.

[0105] The sealing portion 66 is a resin component that seals the space S1 between two adjacent bipolar electrodes 10A, 10A. The sealing portion 66 is rectangular in shape when viewed from the stacking direction and is fused to the edge of the current collector 71. The sealing portion 66, when viewed from the stacking direction, surrounds and integrates the plurality of bipolar electrodes 10A and the plurality of spacers 13 contained in the battery stack 5A. In the first embodiment, a sealing body 63 is formed by integrating a plurality of sealing portions 66 arranged in the stacking direction of the battery stack 5A. In the second embodiment, the positive current collector 61 and the negative current collector 62 are also surrounded by sealing portions 66 when viewed from the stacking direction.

[0106] The outermost membrane 67 is a component provided on the surface of each closure portion 66 and has insulating properties. The outermost membrane 67 covers the outer surface 66s of each closure portion 66, thereby improving the insulation at the outer surface 66s. The outermost membrane 67 is formed, for example, by applying a coating to the outer surface 66s and then drying the coating. The coating is, for example, a coating made by dissolving an insulating synthetic resin in an organic solvent. When multiple energy storage devices 1E are stacked along the stacking direction, the outermost membrane 67 may also be provided across multiple energy storage devices 1E.

[0107] In the second embodiment, the temperature sensor 101 of the temperature detection unit 100 is disposed between two adjacent bipolar electrodes 10A, 10A in the stacking direction among the plurality of bipolar electrodes 10A included in the battery stack 5A. For example, the temperature sensor 101 is disposed in the space S1 enclosed by the current collector 71 (first current collector) of one of the two bipolar electrodes 10A, 10A, the current collector 71 (second current collector) of the other bipolar electrode 10A, and the enclosure 66 sandwiched between the two bipolar electrodes 10A, 10A. Alternatively, the temperature sensor 101 is disposed inside any one of the battery cells 2D to 2F. In the second embodiment, from the viewpoint of suppressing the capacity decrease of the negative electrode active material layer 23B, the temperature sensor 101 is embedded in the center of the positive electrode active material layer 22C of one of the bipolar electrodes 10A when viewed from the stacking direction. Although not shown, the temperature sensor 101 is connected to a wire.

[0108] In the energy storage device 1E of the second embodiment described above, the temperature sensing unit 100s is disposed in the center of the space S enclosed by the sealing part 66 and the two bipolar electrodes 10A, 10A. Therefore, in the second embodiment, the temperature sensing unit 100s can also accurately measure the internal temperature of the energy storage device 1E. In addition, by disposing such two bipolar electrodes 10A, 10A, for example, at or near the center of the battery stack 5A, the temperature difference between the bipolar electrode 10A located at the edge in the stacking direction and the bipolar electrode 10A located at the center in the stacking direction can be accurately measured.

[0109] (Third Implementation)

[0110] The energy storage device according to the third embodiment will now be described. In this third embodiment, descriptions that overlap with the first embodiment, its variations, and the second embodiment described above will be omitted. Therefore, the following description will primarily focus on the differences from the first embodiment, its variations, and the second embodiment described above.

[0111] Figure 11 This is a schematic cross-sectional view showing the energy storage device according to the third embodiment. Figure 11 As shown, the energy storage device 1F includes: two adjacent battery stacks 5B (a first stack and a second stack) in the stacking direction, a pair of cooling members CM (a first cooler and a second cooler), and a temperature detection unit 100. Additionally, although not shown, the energy storage device 1F includes a pair of restraining members that constrain the two battery stacks 5B and the pair of cooling members CM in the stacking direction. The structures of the two battery stacks 5B are identical. Therefore, the structure of one battery stack 5B will be described below.

[0112] Figure 12This is a schematic cross-sectional view showing the battery stack of the third embodiment. Figure 12 As shown, the battery stack 5B includes: a plurality of bipolar electrodes 10B, a plurality of separators 13A, a positive terminal electrode 64A, and a negative terminal electrode 65B. Each of the plurality of bipolar electrodes 10B includes: a current collector 71A, a positive active material layer 22C, and a negative active material layer 23B. In the third embodiment, each of the plurality of separators 13A has a single-layer structure, but is not limited thereto. At least a portion of the peripheral portion of the separator 13A is flexible. The positive terminal electrode 64A includes a current collector 71A and a positive active material layer 22C. The negative terminal electrode 65A includes a current collector 71A and a negative active material layer 23B. At least a portion of the current collectors 71A described above is flexible.

[0113] Each battery stack 5B has two or more individual energy storage cells. In the third embodiment, multiple energy storage cells 2G each have two adjacent bipolar electrodes 10B in the stacking direction and a separator 13A located between the two bipolar electrodes 10B. More specifically, each energy storage cell 2G includes: a current collector 71A and a positive active material layer 22C included in one bipolar electrode 10B; a separator 13A; and a current collector 71A and a negative active material layer 23B included in the other bipolar electrode 10B. Furthermore, in the third embodiment, each energy storage cell 2H includes: a bipolar electrode 10B closest to the positive terminal electrode 64A in the stacking direction; a separator 13A; and a positive terminal electrode 64A. In the third embodiment, each energy storage cell 2I includes: a bipolar electrode 10B closest to the negative terminal electrode 65A in the stacking direction; a separator 13A; and a negative terminal electrode 65A.

[0114] The battery stack 5B is enclosed by the enclosure 200. The enclosure 200 is a component having the same structure and function as the enclosure 63 in the second embodiment described above, and is insulating. The enclosure 200 is rectangular in shape when viewed from the stacking direction and is fused to the edge of the current collector 71A. The enclosure 200 extends from one end of the battery stack 5B in the stacking direction to the other end, enclosing the battery stack 5B. The enclosures 200 that enclose two adjacent battery stacks 5B are separate from each other. A portion of the inner surface of the enclosure 200 can protrude along the current collector 71A. In this case, the periphery of the spacer 13A is disposed on the protrusion at the inner surface. Alternatively, at least a portion of the periphery of a plurality of spacers 13A may be embedded in the enclosure 200. In the third embodiment, one end face 200a of the closed body 200 orthogonal to the stacking direction is aligned with the end face 64a of the positive terminal electrode 64A, and the other end face 200b of the closed body 200 orthogonal to the stacking direction is aligned with the end face 65a of the negative terminal electrode 65A.

[0115] return Figure 11 The temperature sensor 101 of the temperature detection unit 100 is disposed between the two battery stacks 5B in the stacking direction. In the third embodiment, the battery cell (first battery cell) included in one battery stack 5B (first stack) is in contact with the temperature sensor 101. Furthermore, the battery cell (second battery cell) included in the other battery stack 5B (second stack) and adjacent to the first battery cell is in contact with the temperature sensor 101. In the third embodiment, the current collector 71A of the first battery cell is a positive terminal electrode disposed at one end of the first stack in the stacking direction, and the current collector 71A of the second battery cell is a negative terminal electrode disposed at one end of the second stack in the stacking direction. Therefore, the first battery cell is equivalent to... Figure 12 The battery cell 2H shown above is equivalent to the second battery cell mentioned above. Figure 12 The energy storage cell 2I shown has a temperature sensor 101 disposed between the positive terminal electrode of the first energy storage cell and the negative terminal electrode of the second energy storage cell.

[0116] A pair of cooling components CM are components that suppress the temperature rise of the energy storage device 1F, and are made of metal, for example. One cooling component CM (first cooler) is located at one end of the energy storage device 1F in the stacking direction and is in contact with the positive terminal electrode of one battery stack 5B. The other cooling component CM is located at the other end of the energy storage device 1F in the stacking direction and is in contact with the negative terminal electrode of the other battery stack 5B. In other words, the first cooler is in contact with the other end of the first stack in the stacking direction, and the second cooler is in contact with the other end of the second stack in the stacking direction. More specifically, the first cooler is in contact with the negative terminal electrode 65A of the first stack, and the second cooler is in contact with the positive terminal electrode 64A of the second stack. Each cooling component CM is also in contact with the enclosure 200.

[0117] Each pair of cooling components CM includes: a main body CM1, a cooling flow path CM2, and a detection line CM3. The main body CM1 is conductive and, for example, is rectangular plate-shaped. The cooling flow path CM2 is a through-hole formed in the main body CM1, through which cooling fluids such as air can pass. The cooling flow path CM2 extends in a direction orthogonal to the lamination direction, but is not limited thereto. The cooling flow path CM2 can be tortuous or extend in a direction intersecting the lamination direction. Multiple cooling flow paths CM2 are provided in the main body CM1. As an example, the multiple cooling flow paths CM2 are formed equally spaced and parallel to each other. The detection line CM3 is provided at one end of the main body CM1 and is electrically connected to the main body CM1.

[0118] Thus, each cooling component CM has a cooling flow path CM2 provided inside the conductive plate component (main body CM1), and each cooling component CM abuts against and is electrically connected to the positive terminal electrode 64A or the negative terminal electrode 65A. For example, using the detection line CM3 of one cooling component CM and the detection line (not shown) connected to the current collector 71A of the bipolar electrode 10B adjacent to the negative terminal electrode 65A, the battery state (e.g., voltage) of the storage cell 2I, including the negative terminal electrode 65A and the bipolar electrode 10B adjacent to the negative terminal electrode 65A, can be detected. Similarly, using the detection line CM3 of the other cooling component CM and the detection line (not shown) connected to the current collector 81A of the bipolar electrode 10B adjacent to the positive terminal electrode 64A, the battery state (e.g., voltage) of the storage cell 2H can be detected. Therefore, the detection line CM3 can be used to detect the battery state of the storage cell. Each cooling component CM has the function of transmitting constraint load to the corresponding battery stack 5B. In the third embodiment, the cooling member CM extends from the central portion of the current collector 71A to the periphery of the current collector 71A in a manner that overlaps with the enclosure 200 when viewed from the stacking direction.

[0119] In the energy storage device 1F of the third embodiment described above, the temperature sensing unit 100 is disposed between the two battery stacks 5B (i.e., at the center of the energy storage device 1F in the stacking direction). Therefore, in the third embodiment, the temperature sensing unit 100 can also accurately measure the internal temperature of the energy storage device 1F. Furthermore, by using multiple temperature sensing units 100, for example, the temperature difference between the center of the energy storage device 1F in the stacking direction and one end of the energy storage device 1F in the stacking direction can be accurately measured. Moreover, each battery stack 5B is enclosed by the enclosure 200. Therefore, the temperature sensor 101 can be disposed without compromising the sealing of each battery stack 5B.

[0120] In the third embodiment described above, the energy storage device 1F includes a cooling member CM. Therefore, while maintaining the temperature of the energy storage device 1F appropriately, the internal temperature of the desired battery stack 5B can be precisely measured using the temperature sensor 101.

[0121] Hereinafter, variations of the third embodiment described above will be described. In the following variations, descriptions that overlap with the third embodiment described above will be omitted. Therefore, the following mainly describes the differences from the third embodiment described above.

[0122] Figure 13 This is a schematic cross-sectional view showing a modified example of the energy storage device according to the third embodiment. Figure 13As shown, the energy storage device 1G differs from the aforementioned energy storage device 1F in that it further includes a conductive plate CP located between the two battery stacks 5B. The conductive plate CP is a component that electrically connects the two battery stacks 5B to each other, and is, for example, a metal plate or alloy plate with a rectangular shape. Viewed from the stacking direction, the periphery of the conductive plate CP is located further outward than the battery stacks 5B, but is not limited to this. The conductive plate CP includes a pair of planar main surfaces. One main surface is connected to one end of one battery stack 5B, and the other main surface is connected to the other end of the other battery stack 5B.

[0123] A temperature sensor 101 of the temperature sensing section 100 is disposed inside and / or on the surface of the conductive plate CP. When the temperature sensor 101 is disposed inside the conductive plate CP, the conductive plate CP may also be a hollow component. When the temperature sensor 101 is disposed on the surface of the conductive plate CP, the temperature sensor 101 may also be embedded in the conductive plate CP. The temperature sensor 101 is disposed in the central region of the conductive plate CP as viewed from the stacking direction. The temperature sensor 101 is in contact with at least one of the two battery stacks 5B sandwiching the conductive plate CP.

[0124] In the modified example of the third embodiment described above, the same effect is achieved as in the third embodiment described above. Moreover, deformation of the battery stack 5B caused by the presence of the temperature sensing unit 100 can be suppressed, thus preventing damage to the energy storage device 1G caused by the presence of the temperature sensing unit 100.

[0125] In the third embodiment and the modified examples described above, the energy storage device includes two battery stacks and a pair of cooling members, but is not limited thereto. For example, when two battery stacks connected to each other are configured as one energy storage component, the energy storage device may also include multiple energy storage components and multiple cooling members. In this case, one cooling member is provided between two adjacent energy storage components in the stacking direction. In other words, two adjacent energy storage components can share one cooling member. Furthermore, the energy storage device having multiple energy storage components may also include multiple temperature sensing units.

[0126] The preferred embodiments and modifications of this disclosure have been described in detail above, but this disclosure is not limited to the above embodiments and modifications. The above embodiments and modifications can also be appropriately combined. For example, the first embodiment and the second embodiment can be combined with each other. In this case, in the first embodiment, the outer surface of the sealing portion can also be covered by an outermost film made of insulating resin. For example, the first embodiment and the first modification can also be combined with each other. In this case, in the first embodiment, the outer surface of the sealing portion can also be covered by a metal film or the like. For example, the first modification and the third modification can also be combined with each other. For example, the second embodiment can also be combined with the first modification or the second modification. In this case, in the second embodiment, the outer surface of the sealing portion may not be covered by an outermost film made of insulating resin, but by a metal layer. For example, the second embodiment and the third embodiment can also be combined with each other. In this case, the temperature sensing unit can be disposed both between the two battery stacks and inside at least one battery stack.

[0127] In the above embodiments and modifications, one surface of the first current collector has an adhesive surface for bonding to the edge of the separator with a first adhesive layer, but this is not a limitation. For example, one surface of the second current collector may have an adhesive surface for bonding to the edge of the separator with a second adhesive layer. In this case, one surface of the second current collector includes a coated area with a negative electrode active material layer and a non-coated area without a negative electrode active material layer. Furthermore, the non-coated area is disposed around the coated area and includes the aforementioned adhesive surface, with the sealing portion bonded to the first adhesive layer at the edge of the separator.

[0128] In the above embodiments and variations, the temperature detection unit has one temperature sensor, but is not limited thereto. Figure 14 (a) is a schematic top view showing the main part of an example of a temperature detection unit. Figure 14 The temperature sensing unit 100B shown in (a) has multiple temperature sensors 101 for measuring the temperature distribution of the same battery cell. Each of the multiple temperature sensors 101 is electrically connected to a wire 102. Each temperature sensor 101 is, for example, connected to a base film 102b of the wire 102 (see reference). Figure 2(b) Encapsulation. Multiple temperature sensors 101 are arranged separately from each other when viewed in the stacking direction. As a specific example, multiple temperature sensors 101 are arranged sequentially along the long axis of the wire 102, and adjacent temperature sensors 101 are separated from each other in the aforementioned long axis direction. Thus, for example, when multiple temperature sensors 101 are arranged in the same space, the temperature detection unit 100B can detect the temperature distribution within that space. Alternatively, a portion of the multiple temperature sensors 101 may be embedded in the positive or negative electrode active material layer, while another portion may be exposed from the positive and negative electrode active material layers. Alternatively, a portion of the multiple temperature sensors 101 may be embedded, for example, in a closed structure.

[0129] Furthermore, when the temperature detection unit 100B has multiple temperature sensors 101, the space allocated to some of the temperature sensors 101 may differ from the space allocated to other temperature sensors 101. In this case, the first embodiment described above can be combined with the fourth modification described above, or the first modification described above can be combined with the second modification described above.

[0130] Figure 14 (b) is a schematic top view showing the main parts of another example of a temperature sensing unit. Figure 14 As shown in (b), voltmeter terminals 111 and 112 (voltage detection units) are provided on the conductor 102A. The voltmeter terminals 111 and 112 are connected to the voltage detection conductive parts 102c and 102d, respectively, and protrude from the base film 102b. The voltmeter terminal 111, for example, contacts a current collector contained in a predetermined bipolar electrode (or a suspected bipolar electrode). The voltmeter terminal 112, for example, contacts a current collector contained in a bipolar electrode different from the aforementioned predetermined bipolar electrode. Furthermore, by cutting a portion of the conductor 102A, the voltmeter terminals 111 and 112 can be easily positioned at different locations, even if they are formed on the same substrate. By using such a conductor 102A, the voltage of any part of the energy storage device can be measured.

[0131] In the above embodiment, the temperature sensing element is embedded in the positive electrode active material layer, but it is not limited thereto. The temperature sensing element may also be embedded in the negative electrode active material layer. Alternatively, in a portion of the battery stack, the temperature sensing element may be embedded in the positive electrode active material layer, while in another portion of the battery stack, a different temperature sensing element may be embedded in the negative electrode active material layer.

[0132] In the first modification described above, the temperature sensing unit is housed in a groove provided in the positive electrode active material layer, but this is not a limitation. For example, the temperature sensing unit may also be housed in a groove provided in the negative electrode active material layer. Furthermore, if the temperature sensing unit is housed in a groove provided in the positive electrode active material layer, a groove may not be provided in the negative electrode active material layer. In this case, the capacity of the negative electrode can be sufficiently ensured. Additionally, in the first modification described above, grooves are provided in the positive electrode active material layers of all the battery cells included in the battery stack, but this is not a limitation. For example, grooves may only be provided in the positive electrode active material layers of the battery cells including the temperature sensing unit. In this case, grooves may only be provided in the negative electrode active material layers of the battery cells including the temperature sensing unit, or grooves may not be provided in the negative electrode active material layers of any of the battery cells. This effectively suppresses the capacity reduction of the energy storage device caused by the provision of the temperature sensing unit.

[0133] In the second variation described above, the temperature sensing unit is housed in a recess provided in the positive electrode active material layer, but this is not a limitation. For example, the temperature sensing unit may also be housed in a recess provided in the negative electrode active material layer. Alternatively, in a portion of the battery stack, the temperature sensing unit may be housed in a recess provided in the positive electrode active material layer, while in another portion of the battery stack, a separate temperature sensing unit may be housed in a recess provided in the negative electrode active material layer.

[0134] In the fourth variation described above, a recess for housing a temperature sensor is provided in the second current collector included in one of the battery cells, but this is not a limitation. For example, the aforementioned recess may also be provided in the first current collector included in another battery cell. In other words, in the stacking direction, the portion of the first current collector in the other battery cell that overlaps with the temperature sensor may also be recessed toward the positive electrode active material layer in that other battery cell. Alternatively, the aforementioned recess may be provided in both the second current collector and the first current collector. That is, when the temperature sensor is disposed between two adjacent battery cells, a recess for housing the temperature sensor may be provided in at least one of the first current collector of one battery cell and the second current collector of the other battery cell.

[0135] Explanation of reference numerals in the attached figures

[0136] 1. 1A~1G...Energy storage device; 2. 2A~2I...Energy storage cell; 5. 5A, 5B...Battery stack; 11...Positive electrode; 12...Negative electrode; 13...Separator; 13a...Substrate layer; 13aa...First side; 13ab...Second side; 13b...First adhesive layer; 13c...Second adhesive layer; 13e, 20e, 21e...Edge; 14...Sealing part; 14a...Sealing body; 15...Metal layer; 20...First current collector; 20a, 21a...One side; 20b, 21b...The other side; 21...Second current collector; 22. 22A~22C...Positive electrode active material layer; 22a... 22d...recess, 23, 23A, 23B...negative electrode active material layer, 23a...groove, 25...resin frame, 30...constraint member, 64, 64A...positive electrode terminal, 65, 65A...negative electrode terminal, 71, 71A...current collector, 100, 100A, 100B...temperature sensing part, 101...temperature sensor, 102, 102A...wire, 102a...conductor foil (conductive part), 102b...base film (insulating part), 103...constantan wire, 111, 112...voltmeter measuring terminal (voltage detection part), 200...enclosure, CM...cooling member, CP...conductive plate, S, S1...space, U1...positive electrode unit, U2...negative electrode unit.

Claims

1. An energy storage device comprising: a plurality of battery cells stacked in a stacking direction; and a temperature sensor for measuring the temperature of at least one of the plurality of battery cells as the object of measurement, characterized in that... Each of the plurality of battery cells has: The positive electrode has a first current collector and a positive electrode active material layer disposed on one surface of the first current collector. The negative electrode has a second current collector and a negative electrode active material layer disposed on one surface of the second current collector, wherein the negative electrode active material layer and the positive electrode active material layer are arranged opposite each other in the stacking direction. A separator disposed between the positive and negative electrodes; and A sealing portion is disposed between the first current collector and the second current collector, which are opposite to each other in the stacking direction, to seal the positive electrode active material layer and the negative electrode active material layer. Viewed from the stacking direction, the temperature sensor is positioned inside the enclosure of the battery cell being measured. The energy storage device includes: A laminate having the plurality of battery cells; and A closed body is formed by integrating the sealing portions of each of the plurality of energy storage cells together, extending from one end of the stacked body to the other in the stacking direction, thus sealing the stacked body. The temperature sensor is disposed between one end and the other end of the laminate in the stacking direction. The plurality of battery cells have a first battery cell and a second battery cell that are adjacent to each other in the stacking direction. The first current collector of the first battery cell and the second current collector of the second battery cell are adjacent in the stacking direction. The temperature sensor is disposed between the first current collector of the first battery cell and the second current collector of the second battery cell. At least the portion of the second current collector of the second battery cell that overlaps with the temperature sensor is recessed toward the negative electrode active material layer of the second battery cell, and the temperature sensor is housed in the recess.

2. The energy storage device according to claim 1, wherein, The temperature sensor is in contact with either the first current collector or the second current collector.

3. The energy storage device according to claim 1 or 2, wherein, Include: The first layer has two or more energy storage cells included in the plurality of energy storage cells; The second stack, which is adjacent to the first stack in the stacking direction, has two or more other energy storage cells included in the plurality of energy storage cells. The first enclosure is provided by integrating the enclosure portions of the energy storage cells included in the first stack with each other, extending from one end of the first stack in the stacking direction to the other end, thereby enclosing the first stack. as well as The second enclosure is formed by integrating the enclosure portions of the battery cells included in the second stack with each other, extending from one end of the second stack in the stacking direction to the other, thus enclosing the second stack. The first current collector of the first energy storage cell, which is one of the energy storage cells included in the first stack, and the second current collector of the second energy storage cell, which is one of the energy storage cells included in the second stack, are adjacent in the stacking direction. The temperature sensor is disposed between the first current collector, which serves as the positive terminal electrode at one end of the first stack, and the second current collector, which serves as the negative terminal electrode at one end of the second stack.

4. The energy storage device according to claim 3, wherein, It also has: A first cooler, which is in contact with the positive terminal electrode of the first laminate; and The second cooler is in contact with the negative terminal electrode of the second stack.

5. The energy storage device according to claim 1 or 2, wherein, Viewed from the stacking direction, the temperature sensor is disposed in the central region of the battery cell of the object being measured.

6. The energy storage device according to claim 1 or 2, wherein, It also includes multiple temperature sensors, including the aforementioned temperature sensor. Multiple temperature sensors are installed in the battery cell of the object being measured. Multiple temperature sensors, arranged separately from each other in the stacking direction, measure the temperature distribution of the battery cell of the object being measured.

7. The energy storage device according to claim 1 or 2, wherein, It also includes a flexible printed circuit board that is electrically connected to the temperature sensor. The temperature sensor is located at one end of the flexible printed circuit board. The other end of the flexible printed circuit board is connected to a control circuit disposed outside the plurality of battery cells.

8. The energy storage device according to claim 7, wherein, The flexible printed circuit board has a voltage detection section that is in contact with the current collector contained in any one of the plurality of battery cells.

9. The energy storage device according to claim 7, wherein, The flexible printed circuit board has a conductive portion connected to the temperature sensor and an insulating portion covering the conductive portion. The temperature sensor is covered by the insulating part.

Images