Blister detection device

Abstract

To prevent casing breakage and the generation of unpleasant odors by being able to more accurately grasp and address deterioration of battery cells from the perspective of swelling of the battery cells.SOLUTION: A blister detection device according to an embodiment includes a housing that houses a plurality of battery cells, and a monitoring notification unit that notifies a user a case in which the swelling displacement amount of the battery cell detected by a detection unit exceeds a predetermined amount.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a bulge detection device.

Background Art

[0002] Conventionally, techniques for diagnosing degradation for the purpose of reusing battery cells have been proposed. The degradation of a lithium-ion battery cell can be quantified by an increase in internal resistance and a decrease in capacity. In addition to quantifying the degradation of a battery cell, when a lithium-ion battery cell has a rectangular parallelepiped shape, due to gas generation caused by decomposition of an electrolytic solution, a positive electrode, and a negative electrode, for example, a side surface with a larger area (hereinafter referred to as a long side surface) expands, and then, a side surface with a smaller area (hereinafter referred to as a short side surface) expands. This phenomenon is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above, and aims to provide a swelling detection device that can more accurately grasp and address the deterioration of battery cells from the perspective of swelling of the battery cells, thereby preventing casing rupture and the generation of off-odors. [Means for solving the problem]

[0006] The swelling detection device of this embodiment comprises a housing containing multiple battery cells, and a device provided at a predetermined location on the housing. When contact is made with a predetermined circumferential surface of the battery cell, or when contact with the housing is released, Battery cell swelling The amount of displacement exceeded a predetermined amount. Detect It has a detection element that maintains the detection state. The system comprises one or more detection units, and a monitoring notification unit that notifies the system when the amount of swelling displacement of a battery cell detected by the detection units exceeds a predetermined amount. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic block diagram of the battery system according to the embodiment. [Figure 2] Figure 2 is an overview perspective view of the battery module itself. [Figure 3] Figure 3 is a plan view of the battery module itself. [Figure 4] Figure 4 is an explanatory diagram illustrating an example configuration of the detection unit group. [Figure 5] Figure 5 is an explanatory diagram of the deformation that occurs due to the degradation of battery cells. [Figure 6] Figure 6 illustrates how repeated charging and discharging of a cell over a wide range of states of charge (SOC) at a certain temperature can cause cell degradation, which is explained by an increase in internal resistance and a decrease in capacity. [Figure 7A] FIG. 7A is an explanatory diagram (part 1) of deformation due to deterioration of a conventional battery module. [Figure 7B] FIG. 7B is an explanatory diagram (part 2) of deformation due to deterioration of a conventional battery module. [Figure 8] FIG. 8 is a schematic configuration block diagram of the detection unit according to the first embodiment. [Figure 9A] FIG. 9A is an explanatory diagram of the state in the normal state of the first embodiment. [Figure 9B] FIG. 9B is an explanatory diagram of the state when bulging in the first embodiment. [Figure 10] FIG. 10 is a schematic configuration block diagram of the detection unit according to the second embodiment. [Figure 11A] FIG. 11A is an explanatory diagram of the state in the normal state of the second embodiment. [Figure 11B] FIG. 11B is an explanatory diagram of the state when bulging in the second embodiment. [Figure 12] FIG. 12 is a schematic configuration block diagram of the detection unit according to the third embodiment. [Figure 13A] FIG. 13A is an explanatory diagram of the state in the normal state of the third embodiment. [Figure 13B] FIG. 13B is an explanatory diagram of the state when bulging in the third embodiment. MODE FOR CARRYING OUT THE INVENTION

[0008] Next, embodiments will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration block diagram of the battery system according to the embodiment. The battery system 20 includes a battery unit 21 and a controller 22.

[0009] The battery unit 21 includes a plurality of battery modules 10, a positive electrode side contactor (MC) 31P, a negative electrode side contactor (MC) 31N, a positive electrode side service disconnect (SDC) 32P, a negative electrode side service disconnect (SDC) 32N, a fuse 33, a current sensor (CT) 34, and a BMU (Battery Management Unit) 35.

[0010] The battery module 10 includes a battery module main body 10A and a CMU (Cell Monitoring Unit) 10B. In the above configuration, between the CMUs 10B, the CMU s 10B, the BMU 35, and the controller 22, they can communicate with each other via a CAN (Controller Area Network) as a communication network.

[0011] The battery module main body 10A, in this embodiment, although will be described in detail later, constitutes a 2P12C module in which 24 battery cells are connected in 2 parallel and 12 series (2P12S). The CMU 10B monitors the voltage and temperature of each of the plurality of battery cells constituting the battery module main body 10A and notifies the BMU 35.

[0012] < The positive electrode side contactor (MC) 31P connects or disconnects the positive electrode side of the battery unit 21 from the main circuit 40. The positive electrode side contactor (MC) 31P connects or disconnects the positive electrode side of the battery unit 21 from the main circuit 40.

[0013] The negative electrode side contactor (MC) 31N connects or disconnects the negative electrode side of the battery module main body 10A from the main circuit 40

[0014] The positive side service disconnect (SDC) 32P and the negative side service disconnect (SDC) 32N disconnect all battery modules 10 from the main circuit 40 when the battery modules 10 are installed into the battery unit 21, when the battery unit is removed, or during maintenance.

[0015] The fuse 33 blows, for example, when a current exceeding a predetermined value flows, such as in the case of an overcurrent, thereby protecting all battery modules 10 from the main circuit 40.

[0016] The current sensor (CT) 34 detects the current value of the current flowing from the battery unit 21 to the main circuit 40 or the current flowing from the main circuit 40 to the battery unit, and outputs a current detection signal to the BMU 35.

[0017] The BMU (Battery Management Unit) 35 monitors the status of the battery cells and, consequently, the battery module body 10A, based on notifications of the voltage and temperature of each of the multiple battery cells constituting the battery module body 10A, which are notified by the CMU 10B that makes up each battery module 10, and protects the battery unit 21 when an abnormality is detected.

[0018] Based on the state of the main circuit 40 and the communication results with the BMU 35, the controller 22 controls one battery unit via the BMU 35 in the example shown in Figure 1. It is also possible to configure the controller to control multiple battery units, each via its own BMU 35.

[0019] Figure 2 is an overview perspective view of the battery module itself. Figure 3 is a plan view of the battery module body. In Figures 2 and 3, for ease of understanding, the top cover (upper housing), the busbars that electrically connect the terminals of the battery module body 10A, and the flexible circuit board of the CMU 10B, which is positioned opposite the top surface of the battery module body 10A, are omitted from the illustration.

[0020] In Figure 2, the battery module body 10A is equipped with multiple (24 in the case of Figure 2) battery cells 11. All battery cells 11 are housed in a metal container having a rectangular parallelepiped shape, and are further housed in a casing 10C made of resin and some metal components. As shown in Figures 2 and 3, the battery cell 11 is equipped with a positive terminal 11P, a negative terminal 11N, and an opening valve 11G on its top surface.

[0021] On the side of the casing 10C (the long side in Figure 2), there are multiple detection elements 12 for detecting swelling due to deterioration of the battery cell 11, and multiple detection circuits 13 for processing the output signals of the detection elements 12. The multiple detection elements 12 and the multiple detection circuits 13 constitute a group of detection units.

[0022] Here, we will describe an example configuration of the detection unit group. Figure 4 is an explanatory diagram illustrating an example configuration of the detection unit group. The detection unit group 50 comprises multiple detection units 51. Each detection unit 51 is equipped with a detection element 12 and a detection circuit 13.

[0023] According to the above configuration, the detection element 12 detects swelling of the battery cell 11 and, consequently, deformation of the casing 10C, and the CMU 10B, BMU 35, or controller 22, which function as monitoring and notification units, notify the user of this fact.

[0024] In this case, the notification method will be one of a predetermined method, such as displaying the information on the screen or illuminating the notification light. As a result, users can understand the situation before it escalates to the point of opening the release valve or damaging the casing, which would otherwise be necessary to ensure the safety of the battery cell 11, as described later.

[0025] Next, before describing the operation of the embodiment, we will explain in detail the problems of the conventional approach. Figure 5 is an explanatory diagram of the deformation that occurs due to the degradation of battery cells. As gas accumulates inside the battery cell 11 due to degradation, it begins to swell, as shown by the dashed line 11X in Figure 5.

[0026] In this case, the release valve 11G provided on the top surface of the battery cell 11 opens when the internal pressure of the battery cell 11 exceeds a predetermined internal pressure due to the gas accumulated inside the battery cell 11, thereby releasing the gas to the outside of the battery cell 11.

[0027] The release of gas caused the electrolyte, which is a Class II petroleum product, to volatilize, generating an unpleasant odor. Furthermore, if the battery cell 11 was housed in a resin casing, there was a risk that the resin casing would break, causing the battery cell 11 to protrude. Incidentally, there may be no correlation between an increase in the internal resistance of the battery cell 11, a decrease in its capacity, or both, and an increase in displacement, which is a sign that the battery cell 11 is beginning to swell.

[0028] Figure 6 illustrates how repeated charging and discharging of a cell over a wide range of states of charge (SOC) at a certain temperature can cause cell degradation, which is explained by an increase in internal resistance and a decrease in capacity. In the example shown in Figure 6, after n days, the capacitance has decreased by only 1% and the internal resistance has increased by 10% compared to the factory shipment state.

[0029] Furthermore, it can be seen that the swelling and displacement increase rapidly from n days onward. However, even when the charging / discharging conditions and temperature conditions differed, the increase in internal resistance and decrease in capacity still occurred due to degradation within the battery cell, but swelling did not necessarily occur.

[0030] In other words, the swelling of battery cell 11 was not always correlated with an increase in internal resistance or a decrease in capacity. In other words, even if an increase in internal resistance or a decrease in capacity was observed, there was a risk that it would not be possible to predict when the battery cell 11 would start to swell or when it would need to be replaced, nor could the risk of the battery cell swelling be assessed.

[0031] Figure 7A is an explanatory diagram (part 1) of the deformation that occurs due to the degradation of a conventional battery module. As shown in Figures 2 and 3, the battery module 10 houses multiple battery cells 11 arranged in series and parallel, and the battery cells 11 are fixed to the bottom side of a resin casing 10C with, for example, adhesive BD.

[0032] Primarily due to the degradation of the battery cells 11 caused by repeated charging and discharging, swelling occurs in the metal container (so-called cell can) of the battery cell 11, as explained in Figure 5. Since the swelling mainly progresses from the long side, the dimensions of the cell increase in the direction perpendicular to the long side. The battery module 10 is usually designed to account for some degree of swelling of the battery cells 11, so when the battery cells 11 begin to swell, the side walls 10CS of the casing 10C also swell.

[0033] Figure 7B is an explanatory diagram (part 2) of the deformation that occurs due to the degradation of a conventional battery module. However, if the casing 10C is made of a softer resin than the metal container of the battery cell 11, the crack may propagate and break, as shown in Figure 7B, and the battery cell 11 may continue to swell.

[0034] This condition damages the external appearance of the battery module 10, and if left untreated, the release valve 11G will eventually open, releasing the volatile electrolyte and causing an unpleasant odor.

[0035] Therefore, in this embodiment, the swelling of the battery cell 11 is constantly monitored, and if a predetermined amount of swelling is detected, a notification is sent.

[0036] [1] First Embodiment Figure 8 is a schematic block diagram of the detection unit according to the first embodiment. The detection unit 51 includes a mechanical switch MSW that functions as a detection element 12 and has one end connected to the positive side monitoring terminal TP of the CMU 10B, a first resistor R1 that functions as a detection circuit 13A and has one end connected to the other end of the mechanical switch MSW and the other end connected to the negative side monitoring terminal TN of the CMU 10B, and a second resistor R2 that functions as a detection circuit 13A and is connected in parallel to the mechanical switch MSW and the first resistor R1.

[0037] In the above configuration, a predetermined voltage (for example, +5 volts) is applied by the CMU10B between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B.

[0038] Figure 9A is an explanatory diagram of the normal state of the first embodiment. As shown in Figure 9A, the mechanical switch MSW, which is provided on the side wall 10CS of the casing 10C, is in contact with and pressed against the side wall 10CS of the casing 10C, and is in the ON state.

[0039] As a result, as shown in Figure 8, the first resistor R1 and the second resistor R2 are connected in parallel, and their combined resistance is smaller than the resistance of the second resistor R2.

[0040] Figure 9B is an explanatory diagram of the state during swelling in the first embodiment. As shown in Figure 9B, when the battery cell 11 swells and presses the side wall 10CS of the casing 10C outward (in the direction of the arrow in Figure 9B), the mechanical switch MSW provided on the side wall 10CS of the casing 10C is no longer pressed against the side wall 10CS of the casing 10C, and therefore turns off.

[0041] As a result, the first resistor R1 is electrically disconnected from the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B, and only the second resistor R2 is connected between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B. In this state, the voltage between the positive terminal TP and the negative terminal TN of the CMU10B will increase compared to the normal state.

[0042] Therefore, the detection voltage of the CMU10B will be higher than under normal conditions, and the CMU10B will notify that the amount of bulging displacement has exceeded a predetermined displacement threshold.

[0043] As a result, according to this first embodiment, as shown in Figure 7B, it is easy to avoid the crack propagating and rupturing, and the battery cell 11 continuing to swell. Therefore, the external shape of the battery module 10 is not damaged, and the release valve 11G does not open, preventing the release of volatile electrolyte and the generation of an unpleasant odor.

[0044] Therefore, it becomes possible to detect and address the degradation of the battery cell 11, and consequently the battery module 10, at an early stage.

[0045] [2] Second embodiment Figure 10 is a schematic block diagram of the detection unit according to the second embodiment. The detection unit 51 includes a normally closed switch NCSW which functions as a detection element 12, with one end connected to the positive side monitoring terminal TP of the CMU 10B and the other end connected to the negative side monitoring terminal TN of the CMU 10B, and a first resistor R11 which functions as a detection circuit 13B and is connected in parallel to the normally closed switch NCSW.

[0046] In the above configuration, a predetermined voltage (for example, +5 volts) is applied by the CMU10B between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B.

[0047] Figure 11A is an explanatory diagram of the normal state of the second embodiment. As shown in Figure 11A, for example, the normally closed switch NCSW is provided on the side wall 10CS of the casing 10C, and the push button portion is positioned opposite the location where the battery cell 11 is expected to bulge more, and is in the OFF state.

[0048] As a result, as shown in Figure 10, the normally closed switch NCSW and the first resistor R11 are connected to the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B. The voltage between the positive side monitoring terminal TP and the negative side monitoring terminal TN is lower than when only the first resistor R11 is connected to the negative side monitoring terminal TN of the CMU10B.

[0049] Figure 11B is an explanatory diagram of the swelling state in the second embodiment. As shown in Figure 11B, when the battery cell 11 swells and presses against the push button portion of the normally closed switch NCSW located on the side wall 10CS of the casing 10C, the push button portion of the normally closed switch NCSW located on the side wall 10CS of the casing 10C is pressed, and thus the switch turns off.

[0050] As a result, the first resistor R1 is electrically disconnected from the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B, and only the second resistor R2 is connected between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B. In this state, the voltage between the positive terminal TP and the negative terminal TN of the CMU10B will increase compared to the normal state.

[0051] Therefore, the detection voltage of the CMU10B will be higher than under normal conditions, and the CMU10B will notify that the amount of bulging displacement has exceeded a predetermined displacement threshold.

[0052] As a result, this second embodiment also makes it easy to avoid the crack propagating and rupturing, as shown in Figure 7B, and the battery cell 11 continuing to swell. Therefore, the external shape of the battery module 10 is not damaged, and the release valve 11G does not open, preventing the release of volatile electrolyte and the generation of an unpleasant odor.

[0053] Therefore, it becomes possible to detect and address the degradation of the battery cell 11, and consequently the battery module 10, at an early stage.

[0054] [3] Third embodiment Figure 12 is a schematic block diagram of the detection unit according to the third embodiment. Incidentally, the swelling of the battery cell 11 does not decrease before the release valve 11G is opened.

[0055] Therefore, it is not necessary to use a switch that allows for state restoration (such as a mechanical switch MSW or a normally closed switch NCSW) as in the first and second embodiments described above. This is because the battery cell 11, and consequently the battery module 10, that has deteriorated and swollen beyond a certain amount needs to be replaced.

[0056] Therefore, the same operation can be performed even if a component that physically interrupts the current path is provided.

[0057] Therefore, the detection unit 51 of this third embodiment includes a break resistor SR that functions as a detection element 12, with one end connected to the positive side monitoring terminal TP of the CMU 10B, and interrupts the current flow path when physically broken; a first resistor R21 that functions as a detection circuit 13C, with one end connected to the other end of the break resistor SR and the other end connected to the negative side monitoring terminal TN of the CMU 10B; and a second resistor R22 that functions as a detection circuit 13C and is connected in parallel to the break resistor SR and the first resistor R1.

[0058] In the above configuration, a predetermined voltage (for example, +5 volts) is applied by the CMU10B between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU10B.

[0059] Figure 13A is an explanatory diagram of the normal state of the third embodiment. As shown in Figure 13A, the fracture resistance SR provided at the joint between the side wall 10CS and the bottom wall 10CB of the casing 10C is in an unbroken state and maintains a connected state. As a result, as shown in Figure 12, the series-connected break resistor SR and the first resistor R21 are connected in parallel with the second resistor R22, and their combined resistance is smaller than the resistance of the second resistor R22 alone.

[0060] Figure 13B is an explanatory diagram of the state during swelling in the third embodiment. As shown in Figure 13B, when the battery cell 11 swells and presses the side wall 10CS of the casing 10C outward (in the direction of the arrow in Figure 9B), causing the joint between the casing 10C and the bottom wall 10CB to break, the break resistance SR provided at the joint between the side wall 10CS and the bottom wall 10CB of the casing 10C also breaks, and the first resistor R21 is electrically disconnected from the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU 10B, leaving only the second resistor R22 connected between the positive side monitoring terminal TP and the negative side monitoring terminal TN of the CMU 10B.

[0061] As a result, the voltage between the positive terminal TP and the negative terminal TN of the CMU10B will increase compared to the normal state. Therefore, the detection voltage of the CMU10B will be higher than under normal conditions, and the CMU10B will notify that the amount of bulging displacement has exceeded a predetermined displacement threshold.

[0062] As a result, according to this third embodiment, the release valve 11G does not open, preventing the release of volatile electrolyte and the generation of an unpleasant odor. Therefore, it becomes possible to detect and address the degradation of the battery cell 11, and consequently the battery module 10, at an early stage.

[0063] [4] Modified examples of embodiments In each of the embodiments described above, the case in which the CMU10B functions as a monitoring and notification unit has been explained. However, in a battery system that includes a BMU35 and a controller (higher-level controller) 22 in addition to the CMU10B, it is possible to make the BMU35 or the controller 22 function as a monitoring and notification unit.

[0064] As shown in Figure 1, the CMU10B is built into multiple battery module bodies. Therefore, to prevent false detection, the BMU35, controller 22, main circuit 40, or all of them may be equipped with a function to notify the higher-level user that swelling is occurring throughout the system if signals indicating increased swelling displacement obtained via the CMU10B are detected from two or more CMU10Bs.

[0065] The CMU10B, BMU35, and controller 22, which function as monitoring and notification units in this embodiment, have a hardware configuration that utilizes a normal computer equipped with a control device such as a CPU and a storage device such as ROM (Read Only Memory) or RAM.

[0066] The programs executed by the CMU10B, BMU35, and controller22, which function as monitoring and notification units in this embodiment, are provided as files in a format installable to USB memory, SSD (Solid State Drive), or executable format, recorded on a computer-readable recording medium such as a CDVD (Digital Versatile Disk).

[0067] Furthermore, the CMU10B, BMU35, and controller22, which function as the monitoring and notification unit of this embodiment, may be configured to be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Alternatively, the CMU10B, BMU35, and controller22, which function as the monitoring and notification unit of this embodiment, may be configured to be provided or distributed via a network such as the Internet.

[0068] Alternatively, the program of this embodiment may be provided pre-installed in a ROM or the like.

[0069] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0070] 10 Battery Modules 10A Battery Module Unit 10B CMU 10C Casing 10CB bottom wall 10CS side wall 11 battery cells 11G Opening valve 11N negative terminal 11P Positive side terminal 11X dashed line 12 detection elements 13, 13A~13C detection circuit 20 Battery Systems 21 Battery Unit 22 controllers 33 fuses 35 BMU 40 Main circuit 50 detection unit group 51 Detection Unit R1 is the first resistor. R2 2nd resistor R11 1st resistor R21 1st resistor R22 2nd resistor BD adhesive MSW Mechanical Switch NCSW Normally Closed Switch SR (Severity Resistance to Breaking) TN Negative side monitoring terminal TP Positive side monitoring terminal

Claims

1. A housing containing multiple battery cells, One or more detection units are provided at a predetermined location on the housing and have a detection element that contacts a predetermined circumferential surface of the battery cell, or when contact with the housing is released, detects that the amount of swelling displacement of the battery cell exceeds a predetermined amount, and maintain the detection state. A monitoring notification unit that notifies the user if the amount of swelling displacement of the battery cell detected by the detection unit exceeds a predetermined amount, A blister detection device equipped with the following features.

2. The detection unit comprises the detection element and A detection circuit that outputs a swelling detection signal based on the state of the detection element, A bulge detection device according to claim 1, comprising:

3. The detection element is configured as a mechanical switch that turns on when it comes into contact with a predetermined circumferential surface of the battery cell when the battery cell swells by a predetermined amount or more. The detection circuit includes a first resistor connected in series with the mechanical switch, The device comprises the mechanical switch and a second resistor connected in parallel to the first resistor. The bulge detection device according to claim 2.

4. The detection element is configured as a normally closed switch that is turned off when the battery cell swells beyond a predetermined amount, by releasing contact with the housing. The detection circuit comprises a first resistor connected in parallel with the normally closed switch, The bulge detection device according to claim 2.

5. The monitoring and notification unit applies a predetermined voltage to the detection unit and determines whether the amount of swelling displacement of the battery cell exceeds a predetermined amount based on the change in the voltage. The bulge detection device according to claim 1.

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