Energy Storage Devices

Abstract

To provide an electric power storage device capable of detecting cell swelling without increasing cell resistance.SOLUTION: The electric power storage device includes: a cell in which a battery element is wrapped in an outer package; a conductive member that covers the sides of the cell; and a detection unit that electrically connects with a conductive member and detects the energized state of the conductive member by supplying current to the conductive member. The conductive member has a structure in which the conduction state of the conductive member changes due to the expansion of the cell.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to an electricity storage device. [Background technology]

[0002] Laminated cells, in which battery elements are wrapped in a laminate film, are known as batteries with high energy density and easy handling. However, in laminated cells, electrolytes and other components may decompose and generate gas when abnormalities such as overcharging or internal short circuits occur. When gas is generated, the laminated cell expands. Therefore, by detecting such expansion, the current flowing through the laminated cell can be controlled to improve safety. Such technology is disclosed, for example, in Patent Document 1.

[0003] Patent Document 1 discloses a battery pack in which a laminate cell is sandwiched between predetermined restraining plates and the laminate cell and the restraining plates are fixed with a belt-shaped fastening member, in which an electrode tab of the laminate cell is fixed to the restraining plate connected to an external power load, and the fixation between the electrode tab and the restraining plate is released when the laminate cell expands. With this battery pack, the external power load and the laminate cell can be electrically disconnected by releasing the fixation between the electrode tab and the restraining plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6825705 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in a laminate cell housing a lithium ion capacitor, a large current of 1000W or more is often applied to a small cell of about 100cc. In this case, high temperature heat is generated in the electrode tab due to the internal resistance of the cell. The battery pack described in Patent Document 1 requires a joint that joins the restraining plate and the electrode tab, and such a joint has a large contact resistance and becomes a heat generating point. This not only causes energy loss due to heat generation, but also causes a problem that the contact state of the joint changes due to deformation due to heat, resulting in a circuit interruption regardless of the expansion of the cell.

[0006] In view of the above circumstances, an object of the present disclosure is to provide an electricity storage device that can detect cell expansion without increasing the resistance of the cell. [Means for solving the problem]

[0007] As one aspect for solving the above-mentioned problems, the present disclosure provides an electricity storage device comprising: a cell in which a battery element is packaged in an exterior body; a conductive member covering a side surface of the cell; and a detection unit electrically connected to the conductive member and detecting a conductive state of the conductive member by supplying a current to the conductive member, wherein the conductive member has a structure in which the conductive state of the conductive member changes due to expansion of the cell.

[0008] In the above-mentioned power storage device, the conductive member may have a structure in which a current-carrying state of the conductive member changes when a tension of 0.5 N to 300 N is applied thereto. The conductive member may have a slit or a notch. Furthermore, the above-mentioned power storage device may include a control unit that controls current supply to the cell, and when the detection unit detects a change in the current-carrying state of the conductive member, the control unit may control the current supply to the cell. Effect of the Invention

[0009] The electric storage device of the present disclosure detects the expansion of the cell by detecting a change in the current-carrying state of the conductive member. Here, the conductive member is a member that covers the side surface of the cell and is not electrically connected to the cell. Therefore, the electric storage device of the present disclosure can detect the expansion of the cell without increasing the resistance of the cell. [Brief description of the drawings]

[0010] [Figure 1] 2 is a schematic diagram of a side surface of an electricity storage device 100 in which a conductive member 20 is observed from the front side. [Diagram 2] 1 shows a schematic diagram of the side surface of the electricity storage device 100 observed from the side surface of the conductive member 20. The top view of the portion enclosed by the dotted line is indicated by an arrow. [Diagram 3] 1 is a schematic diagram for explaining a conductive member 120 arranged so as to wrap around the periphery of the cell stack 15. The top view of the portion indicated by the dotted line is indicated by an arrow. [Figure 4] FIG. 13 is a diagram showing a configuration in which a clip 121 is used as a fixing member. [Diagram 5] 13 is a diagram showing a configuration in which one of the fixing members 21 is provided in a position close to an end face of the cell stack 15. FIG. [Figure 6] FIG. [Figure 7] 13A is a front view of the conductive member 220. FIG. 13B is a side view of the conductive member 220. FIG. 13C is a side view of the conductive member 220 with a protective film 220c disposed thereon. [Figure 8] 1 and shows the electricity storage device 100 after the cell stack 15 has expanded. [Figure 9] 3 corresponds to FIG. 2 and shows the electricity storage device 100 after the cell stack 15 has expanded. [Figure 10] 2 is a schematic diagram of a side surface of an electricity storage device 200 in which a conductive member 20 is observed from the front side. [Figure 11] 4 is a control flow of an embodiment of the power storage device 200. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] [First embodiment] An electricity storage device according to the present disclosure will be described with reference to an electricity storage device 100 as a first embodiment. Fig. 1 shows a schematic side view of the electricity storage device 100 in which a conductive member 20 is observed from the front side. Fig. 2 shows a schematic side view of the electricity storage device 100 in which a conductive member 20 is observed from the side side.

[0012] As shown in Figures 1 and 2, the energy storage device 100 includes a cell stack 15 in which a plurality of cells 10 are stacked, a conductive member 20 covering the side surface of the cell stack 15, and a detection unit 30 that is electrically connected to the conductive member 20 and detects the electrical current flowing through the conductive member 20 by supplying a current to the conductive member 20.

[0013] <Cell 10> The cell 10 is a single cell in which a battery element is packaged in an exterior body 11. The battery element includes a positive electrode, a negative electrode, and an electrolyte. The type of the cell 10 is not particularly limited, and may be a liquid battery or a solid battery. The cell 10 may be a secondary battery or a capacitor. Furthermore, in the cell 10, the type of ions that move within the battery element due to charging and discharging is not particularly limited. For example, known ions such as lithium ions and sodium ions can be mentioned. An example of the cell 10 through which a large current flows and which is prone to expansion is a lithium ion capacitor. Even if the power storage device 100 uses a cell 10 that is prone to such expansion, it is possible to detect the expansion. Therefore, a lithium ion capacitor may be used for the cell 10.

[0014] The exterior body 11 is not particularly limited as long as it is an exterior body that can accommodate the battery element and can be deformed by a change in internal pressure. For example, a laminate film or a metallic housing can be used. From the viewpoint of ease of handling, a laminate film may be used for the exterior body 11. Since a laminate film has a lower rigidity than other exterior bodies, it is likely to expand due to an increase in the internal pressure of the cell 10. However, even if the power storage device 100 uses a cell 10 that is prone to such expansion, it is possible to detect the expansion. Therefore, a laminate film may be used for the exterior body 11. As the laminate film, for example, a known metal laminate such as an aluminum laminate can be used.

[0015] The cell 10 has a pair of electrode tabs (positive electrode tab 12a and negative electrode tab 12b) protruding from the exterior body 11. The positive electrode tab 12a is connected to a positive electrode sealed in the cell 10, and the negative electrode tab 12b is connected to a negative electrode sealed in the cell 10. In FIG. 1, the positive electrode tab 12a and the negative electrode tab 12b are provided on opposing side surfaces of the cell 10. However, the power storage device of the present disclosure is not limited to this, and the positive electrode tab 12a and the negative electrode tab 12b may be disposed on the same side surface of the cell, or on different side surfaces.

[0016] <Cell stack 15> The cell stack 15 is a structure in which the cells 10 are stacked in the thickness direction. A member such as a stack plate or a heat spreader may be disposed between the stacked cells 10. In the cell stack 15, the electrode tabs of the cells 10 are connected in series. However, in the power storage device of the present disclosure, the connection method of the electrode tabs of the cells is not particularly limited, and may be in series or in parallel. From the viewpoint of passing a large current, the electrode tabs of the cells may be connected in series.

[0017] In the first embodiment, the power storage device 100 has a cell stack 15 in which a plurality of cells 10 are stacked, but the power storage device of the present disclosure is not limited to this and may have only one cell. The same applies to the second embodiment described below. However, from the viewpoint of passing a large current, the power storage device of the present disclosure may have a cell stack in which a plurality of cells are stacked.

[0018] <Conductive member 20> The conductive member 20 is a member that covers the side surface of the cell stack 15. The material of the conductive member 20 is not particularly limited as long as it is a conductive member. For example, it may be a soft metal such as aluminum, or a resin having a conductive material. The conductive material is, for example, graphite, metal powder, or a conductive polymer. The type of resin is not particularly limited, and a known resin can be appropriately adopted.

[0019] The shape of the conductive member 20 is not particularly limited, and may be a tape, a band, or a line. A plurality of conductive members may be bundled together to form a single conductive member 20. Furthermore, in order to reinforce the conductive member 20, a resin film or the like may be attached to the surface of the conductive member 20. Furthermore, in order to fix the conductive member 20 to the cell stack 15, the resin film may have adhesive properties. This allows the conductive member 20 to be easily fixed to the side surface of the cell stack 15.

[0020] The side surface of the cell stack 15 on which the conductive member 20 is arranged is not particularly limited, and the conductive member 20 may be arranged on any side surface. However, in order to avoid increasing the resistance of the cells 10, it is necessary to consider not electrically connecting the conductive member 20 to the electrode tabs of the cells 10. Therefore, from the viewpoint of preventing contact between the conductive member 20 and the current path (the current path formed by connecting the electrode tabs of the cells 10), the conductive member 20 may be arranged at least on the side surface on which the current path of the cells 10 is not arranged. This prevents energy loss due to contact between the conductive member 20 and the current path (electrode tab), and prevents a decrease in the accuracy with which the detection unit 30 detects a change in the current-carrying state of the conductive member 20.

[0021] The conductive member 20 may cover at least a part of the side surface of the cell stack 15. This allows the expansion of the cells 10 covered by the conductive member 20 to be detected. However, from the viewpoint of detecting the expansion of the entire cell stack 15, as shown in FIG. 1, the conductive member 20 may cover the side surface of the cell stack 15 in the thickness direction. In particular, the conductive member 20 may cover the side surface of the cell stack 15 from one end to the other end in the thickness direction. The conductive member 20 may not only cover only one side surface of the cell stack, but also cover the other surfaces. For example, the conductive member 20 may cover one side surface and the end surface in the thickness direction of the cell stack 15. The conductive member 20 may be arranged so as to wrap around the cell stack 15. That is, the conductive member 20 may cover both opposing side surfaces and both end surfaces in the thickness direction of the cell stack 15. FIG. 3 shows a form having a conductive member 120 arranged so as to wrap around the cell stack 15.

[0022] 3, by arranging the conductive material 120 so as to wrap around the cell stack 15, the current flow state of the conductive material 120 can change even if the end face of the cell stack 15 expands. Therefore, with this type of power storage device configuration, it is possible to detect not only the expansion of the side face of the cell stack 15, but also the expansion of the end face.

[0023] The method for arranging the conductive member 20 on the side surface is not particularly limited, and the conductive member 20 may be attached with an adhesive or may be arranged using a predetermined fixing member 21. In this case, the conductive member 20 may be fixed with a predetermined tension. An insulating adhesive may be used as the adhesive, but a conductive adhesive may be used as the adhesive for connecting the conductive member 20 and the fixing member 21. The conductive adhesive is an adhesive containing a conductive polymer, metal, or carbon powder.

[0024] 1 and 2, fixing members 21, 21 (terminals) are arranged on the respective end faces of the cell stack 15, and the end of the conductive member 20 is fixed to the fixing members 21, 21, respectively, so that the conductive member 20 is arranged on the side of the cell stack 15. The end of the conductive member 20 is fixed to the fixing member 21 using a conductive adhesive. Then, as shown in the upper part of FIG. 2, the connection portion 31 of the detection unit 30 is electrically connected to the end of the conductive member 20. This allows the detection unit 30 to detect a change in the current-carrying state of the conductive member 20. The connection form between the connection portion 31 and the conductive member 20 is not particularly limited, and the electrical connection may be made using a coupler or a crimp terminal.

[0025] The fixing member 21 is not particularly limited as long as it can fix the conductive member 20 and connect the conductive member 20 to the detection unit 30. As shown in Fig. 2, a terminal may be used as the fixing member 21. A clip may also be used as the fixing member. Fig. 4 shows an embodiment in which a clip 121 is used as the fixing member.

[0026] 4, the end 20 of the conductive member 20 may be clamped and fixed by a clip 121. The clip 121 may have a predetermined locking mechanism, and the fixed state may be maintained by using the locking mechanism. Then, the end of the conductive member 20 extending from the rear of the clip 121 and the connection portion 31 of the detection portion 30 are electrically connected.

[0027] 1 and 2, the fixing members 21 are arranged on each end surface of the cell stack 15, but the arrangement of the fixing members 21 is not limited thereto. As shown in FIG. 5, one of the fixing members 21 may be provided at a position close to an end surface of the cell stack 15. In the embodiment of FIG. 1 and FIG. 2, since the fixing members 21 are arranged on both end surfaces of the cell stack 15, none of the end surfaces are horizontal, and the electricity storage device 100 cannot be stably placed. On the other hand, as shown in FIG. 5, by placing the fixing member 21 on the side on which the electricity storage device 100 is placed on the placement surface at a position close to the end surface of the cell stack 15, the electricity storage device 100 can be stably placed.

[0028] Here, the conductive member 20 has a structure in which the conductive state of the conductive member 20 changes due to the expansion of the cell 10. Preferably, the conductive member 20 has a structure in which the conductive state of the conductive member 20 changes before the cell 10 expands and reaches the internal pressure limit. In the electricity storage device 100, gas may be generated inside the cell 10 due to a side reaction or a thermal reaction of the battery element, causing the cell 10 to expand. Therefore, the "internal pressure limit" is the internal pressure limit at which cracks, cuts, etc. do not occur in the exterior body 11 of the cell 10 when the internal pressure changes due to the generation of gas inside the cell 10. In particular, since the sealed portion (e.g., laminated sealed portion) of the exterior body 11 that is bonded or welded is easily opened, the internal pressure limit may be the internal pressure limit at which the sealed portion is not opened. The "change in the current state" is a change in the current or voltage of the conductive member 20 detected by the detection unit 30, or an interruption of current flow. The electricity storage device 100 may have a threshold value for determining whether the current state of the conductive member 20 has changed. The threshold value may be set appropriately depending on the conductive member 20. This is because the threshold value changes depending on the amount of current supplied to the conductive member 20 and the material of the conductive member 20. The "structure in which the current flow state changes" is a structure in which a crack or a cut occurs in the conductive member 20 before the cell 10 expands and reaches the internal pressure limit. For example, when a crack occurs in the conductive member 20, the current or voltage of the conductive member 20 detected by the detection unit 30 changes, and when the conductive member 20 is cut, the current to the conductive member 20 is cut. The threshold value for determining whether the current flow state has changed may be set based on the current flow state when a crack or a cut occurs in the conductive member 20. Preferably, the threshold value is set based on the current flow state (cutoff of current) when the current flow state occurs in the conductive member 20.

[0029] Since the power storage device 100 has the conductive member 20, the expansion of the cell 10 covered by the conductive member 20 changes the current-carrying state of the conductive member 20, and therefore the expansion of the cell 10 can be detected. The internal pressure limit of the cell 10 varies depending on the type of the cell 10, and therefore cannot be uniquely determined. Therefore, it is preferable to obtain the internal pressure limit of the cell 10 in advance by experiment or simulation. For example, the structure of the conductive member 20 may be designed so that a change in the current-carrying state occurs with a force sufficiently smaller than (internal pressure limit of the cell 10)×(coverage area of ​​the conductive member 20 in one cell 10). The internal pressure limit of the cell 10 using a laminate film for the exterior body 11 is generally 40 kPa to 100 kPa.

[0030] Since the conductive member 20 has a structure in which the conductive state of the conductive member 20 changes due to the expansion of the cell 10, it is necessary to consider that the conductive member 20 does not easily crack or break during the manufacture of the electricity storage device 100. For example, the conductive member 20 may have a structure in which the conductive state of the conductive member 20 changes when a tension of 0.5N to 300N is applied. This makes it easy to detect the expansion of the cell 10 and also makes it easy to arrange the conductive member 20 on the cell 10. If the tension of the conductive member 20 is less than 0.5N, the conductive member 20 is easily cut, making it difficult to arrange the conductive member 20 on the cell 10. If the tension of the conductive member 20 exceeds 300N, it is easy to detect the expansion of the cell 10. The tension of the conductive member can be measured by a known method such as a test method in accordance with the international standards ASTM D882-18, D883, and D638.

[0031] The conductive member 20 may have a slit or a notch. This makes it easier for the conductive member 20 to change its current-carrying state, and improves the accuracy of detecting the expansion of the cell 10. For example, when using a conductive member 20 with high strength, a slit or a notch may be added to the conductive member 20 to adjust its strength. The shape of the slit or the notch of the conductive member 20 is not particularly limited, but it is preferable that the slit or the notch has an angle with respect to the thickness direction so that the current-carrying state of the conductive member 20 can easily change. For example, the angle of the slit or the notch with respect to the thickness direction may be more than 0°, may be 10° or more, may be 30° or more, may be 45° or more, may be 60° or more, may be less than 180°, may be 170°, may be 150° or less, may be 135° or less, or may be 120° or less.

[0032] An enlarged view of the conductive member 20 is shown in Fig. 6. As shown in Fig. 6, the conductive member 20 has a plurality of cutouts 20a, which gives it a shape in which hexagons are arranged continuously. In this manner, the conductive member 20 may have a shape in which polygons are arranged continuously. By having the cutouts 20a in the conductive member 20, changes in the electrical conduction state are more likely to occur starting from the cutouts 20a. In other words, cracks or cuts are more likely to occur in the conductive member 20 starting from the cutouts 20a.

[0033] 7 shows a conductive member 220 having a plurality of notches 220a on its surface. (a) is a front view of the conductive member 220, and (b) is a side view of the conductive member 220. (c) is a side view of the conductive member 220 when a protective film 220c is disposed thereon.

[0034] As shown in Fig. 7(a), the conductive member 220 has a plurality of notches 220a on its surface, and the conductive member 220 has a structure in which changes in the electrical conduction state are likely to occur starting from the notches 220a. When notches are provided on the surface of the conductive member 220, as shown in Fig. 7(b), a resin film 220b may be attached to the other surface of the conductive member 220 to improve strength. Also, as shown in Fig. 7(c), during the manufacture of the electricity storage device, the conductive member 120 to which a protective film 220c for protecting the surface provided with the notches 220a is attached may be placed on the side of the cell stack 15, and the protective film 220c may then be peeled off.

[0035] <Detection unit 30> The detection unit 30 is a member that is electrically connected to the conductive member 20 and detects the current-carrying state of the conductive member 20 by supplying a current to the conductive member 20. Then, by detecting a change in the current-carrying state of the conductive member 20, the expansion of the cell 10 can be detected. In FIG. 1, the detection unit 30 is electrically connected to each end of the conductive member 20. The detection unit 30 has predetermined connection parts 31, 31, and is connected to the conductive member 20 via the connection part 31. The detection unit 30 can be appropriately selected from known detection devices. The magnitude of the current and voltage that are applied from the detection unit 30 to the conductive member 20 is not particularly limited, and is appropriately set to a magnitude of the current and voltage that makes it easy to detect a change in the current-carrying state of the conductive member 20.

[0036] <Effects> 8 and 9 correspond to FIGS. 1 and 2 and are diagrams of the electricity storage device 100 after the cell stack 15 has expanded. As shown in FIGS. 8 and 9, the expansion of the cell stack 15 (cells 10) changes the electrical conduction state of the conductive member 20. Specifically, the expansion of the cell stack 15 (cells 10) causes the conductive member 20 to break, thereby cutting off electrical conduction from the detection unit 30 to the conductive member 20. The detection unit 30 detects this change in the electrical conduction state of the conductive member 20 (cutoff of electrical conduction). Therefore, the electricity storage device 100 can detect the expansion of the cells 10.

[0037] Furthermore, as described above, the conductive member 20 is not electrically connected to the cell 10. Therefore, the power storage device 100 can detect the expansion of the cell 10 without increasing the resistance of the cell 10.

[0038] <Supplementary Information> By appropriately adjusting the structure of the conductive member 20, the power storage device 100 can detect the displacement of the cell stack 15 in addition to detecting the expansion of the cells 10. Normally, if the conductive member 20 has a structure in which the conductive state of the conductive member 20 changes due to the expansion of the cells 10, the detection unit 30 can detect the change in the conductive state of the conductive member 20, and the power storage device 100 can also detect the displacement of the cell stack 15.

[0039] For example, when an external force is applied to the power storage device 100, the relative position of any of the cells 10 in the cell stack 15 may be displaced. When the relative positions of the cells 10 are displaced, the electrode tabs between the cells 10 may come off, or even if the electrode tabs do not come off, a high load may be applied near the electrode tabs. When the electrode tabs come off, the power storage device 100 may become unusable. In addition, when a high load is applied near the electrode tabs, the battery element connected to the electrode tabs may be damaged. Furthermore, since a large current may flow through a limited cross-sectional area of ​​the electrode tabs, when the electrode tabs are weakened due to the positional displacement, the electrode tabs may generate heat. Thus, the displacement of the relative positions of the cells 10 is undesirable because it leads to an abnormal state of the power storage device 100. The battery pack described in Patent Document 1 does not have a means for detecting such a positional displacement.

[0040] On the other hand, the conductive member 20 of the electricity storage device 100 may crack or cut due to misalignment of the cells 10, which may cause a change in the electrical conduction state. In particular, when the conductive member 20 is attached to the side surface of the cell stack 15, the conductive member 20 is likely to crack or cut due to misalignment of the cells 10, which may cause a change in the electrical conduction state. Therefore, the electricity storage device 100 can detect a misalignment of the relative positions of the cells 10.

[0041] Furthermore, since the power storage device 100 has the conductive member 20, it can detect whether or not a cell 10 has been unintentionally replaced. In other words, if a cell 10 is unintentionally replaced, it is expected that the conductive member 20 will crack or break. Therefore, after a cell 10 is replaced, the detection unit 30 will detect a change in the electrical conduction state of the conductive member 20. In this way, the conductive member 20 also has the role of sealing the cell 10 (cell stack 15).

[0042] [Second embodiment] A power storage device 200, which is a second embodiment of the power storage device of the present disclosure, will be described below. The power storage device 200 is configured by adding a control unit 40 to the power storage device 100. A schematic diagram of the power storage device 200 is shown in FIG.

[0043] 10, the power storage device 200 includes a control unit 40 connected to the detection unit 30 in addition to the configuration of the power storage device 100. The control unit 40 controls the power storage device 200. Specifically, the control unit 40 controls the current supply to the cell stack 15 (the amount of current supply and the stop of current supply). The control unit 40 is a known arithmetic device (computer system) such as a battery management system.

[0044] In the power storage device 200, when the detection unit 30 detects a change in the current-carrying state of the conductive member 20, the control unit 40 controls the current supply to the cell stack 15. This makes it possible to quickly control the power storage device 200 and transition to a safe state. Therefore, it can be said that the power storage device 200 is a safer power storage device.

[0045] An embodiment of a control flow of the power storage device 200 by the control unit 40 will be described below. A control flow of the embodiment is shown in Fig. 11. However, the control of the power storage device 200 by the control unit 40 is not limited to this.

[0046] The control flow according to one embodiment repeatedly executes the following steps S1 to S4.

[0047] In step S1, the control unit 40 determines whether or not it has received information from the detection unit 30 indicating that a change in the current-carrying state of the conductive member 20 has been detected. If the information has not been received, the control unit 40 performs step S1 again. If the information has been received, the control unit 40 proceeds to step S2. "Information indicating that the current-carrying state of the conductive member 20 has changed" is information indicating that the current or voltage of the conductive member 20 detected by the detection unit 30 has changed. This information indicates that an abnormal state such as expansion or displacement has occurred in the cell 10.

[0048] In step S2, the current supply to the cell stack 15 is controlled. For example, the current supply to the cell stack 15 (cells 10) may be reduced or cut off. A safer control is performed according to the state of the power storage device. After step S2, step S3 is performed.

[0049] In process S3, the temperature of the cell stack 15 is measured, and it is determined whether the measured temperature is abnormal. The temperature of the cell stack 15 is measured by a temperature measuring device (not shown). If the measured temperature is abnormal, process S4 is performed. If the measured temperature is not abnormal, the control flow ends.

[0050] In step S4, the temperature of the cell stack 15 is cooled. A cooling device (not shown) is used to cool the cell stack 15. When the temperature of the cell stack 15 has decreased to a predetermined temperature, step S4 is terminated. [Explanation of symbols]

[0051] 10 Cells 11 Exterior body 12a Positive tab 12b Negative tab 15 Cell stack 20, 120, 220 Conductive material 20a Cutout 220a Notch 220b Resin film 220c protective film 21, 121, fixing member 30 Detection unit 31 Connection 40 Control section 100, 200 Energy storage device

Claims

1. A cell in which a battery element is packaged in an exterior body; A conductive member covering a side surface of the cell; a detection unit electrically connected to the conductive member and supplying a current to the conductive member to detect a current-carrying state of the conductive member, the conductive member has a structure in which a current-carrying state of the conductive member changes due to expansion of the cell, the conductive member is not electrically connected to the cell; The conductive member has a shape in which hexagons are continuously arranged, and thus has a plurality of notches, The detection unit has a connection unit that is electrically connected to an end of the conductive member when detecting a current-carrying state of the conductive member. Energy storage device.

2. 2. The power storage device according to claim 1, wherein the conductive member has a structure in which a current-carrying state of the conductive member changes when a tension of 0.5 N to 300 N is applied to the conductive member.

3. A control unit is provided for controlling a current supply to the cell, When the detection unit detects the energization state of the conductive member, the end of the conductive member and the connection unit are electrically connected, and when a change in the energization state of the conductive member is detected, the control unit controls the current supply to the cell. The electricity storage device according to claim 1 or 2.

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