Hydrogen sulfide detection device

Abstract

The present invention provides a hydrogen sulfide detection device that can be applied to battery packs containing battery cells having a sulfide electrolyte and is capable of detecting the generation of hydrogen sulfide with high accuracy. [Solution] The hydrogen sulfide detection device comprises wiring that electrically connects a first node and a second node, and a monitoring circuit that monitors the voltage between the first node and the second node. The wiring includes a pattern formed on a substrate and made of a metal that corrodes in reaction with hydrogen sulfide, and the pattern includes at least one via. Recesses exist on the surface of the substrate, and each of the at least one via is exposed to the outside of the substrate through the recess.

Description

[Technical Field]

[0001] This disclosure relates to a hydrogen sulfide detection device applied to a battery pack that houses battery cells having a sulfide-based electrolyte. [Background technology]

[0002] Solid-state batteries are attracting attention as the next generation of battery cells that make up battery packs. Compared to conventional batteries with liquid electrolytes, solid-state batteries have advantages such as high safety and long lifespan. Solid-state batteries using sulfide-based electrolytes in particular offer high capacity and high output, and are expected to be used in vehicle batteries.

[0003] On the other hand, when a battery cell containing a sulfide-based electrolyte is used as the battery cell for an all-solid-state battery, there is a risk of hydrogen sulfide gas generation due to malfunction. Hydrogen sulfide gas is toxic and can corrode surrounding metal components. Therefore, there is a need for technology to appropriately detect the generation of hydrogen sulfide in battery packs that house battery cells containing sulfide-based electrolytes.

[0004] Patent Document 1 discloses a technique for detecting electrolyte leakage from a battery by providing a substrate with a first copper foil ribbon and a second copper foil ribbon in a battery pack, and measuring the duration of the voltage drop or the number of voltage drops between the first and second copper foil ribbons. In addition, Patent Documents 2 and 3 below are documents that demonstrate the level of technology in this field. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-251985 [Patent Document 2] Japanese Patent Publication No. 2003-035705 [Patent Document 3] International Publication No. 03 / 029801 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] When hydrogen sulfide is generated from a battery cell, it is desirable to detect the generation of hydrogen sulfide as quickly and reliably as possible. In the technology disclosed in Patent Document 1, there is a risk that the reaction with each copper foil ribbon may not proceed sufficiently when only a small amount of hydrogen sulfide is generated, making it impossible to detect the generation of hydrogen sulfide. Thus, there is a need to improve the accuracy of hydrogen sulfide generation detection.

[0007] This disclosure has been made in view of the above-mentioned issues. One of the purposes of this disclosure is to provide a technology that can detect the generation of hydrogen sulfide with high accuracy. [Means for solving the problem]

[0008] One aspect of the present disclosure relates to a hydrogen sulfide detection device applied to a battery pack housing a battery cell having a sulfide-based electrolyte. The hydrogen sulfide detection device comprises wiring electrically connecting a first node and a second node, and a monitoring circuit for monitoring the voltage between the first node and the second node. The wiring includes a pattern formed on a substrate and made of a metal that corrodes in reaction with hydrogen sulfide, the pattern including at least one via. Recesses are present on the surface of the substrate, and each of the at least one via is exposed to the outside of the substrate through the recess. [Effects of the Invention]

[0009] According to this disclosure, hydrogen sulfide gas flows into the via through a recess, and the generation of hydrogen sulfide is detected by the corrosion of the via's metal. Since the incoming hydrogen sulfide remains inside the via, even a small amount of hydrogen sulfide will cause rapid corrosion of the via's metal. Therefore, the generation of hydrogen sulfide can be detected with high accuracy. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the configuration of a hydrogen sulfide detection device according to the first embodiment. [Figure 2] This is a cross-sectional view showing the configuration of the detection unit. [Figure 3] This is a schematic diagram illustrating the operation of a hydrogen sulfide detection device. [Figure 4] This is a flowchart showing the processing flow of the monitoring circuit. [Figure 5] This is a schematic diagram showing an example of via arrangement in the detection unit. [Figure 6] This is a schematic diagram showing an example of a circuit board layout. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described below with reference to the attached drawings. In each drawing, identical or corresponding components are denoted by the same reference numerals, and their descriptions are simplified or omitted.

[0012] 1. Hydrogen sulfide detection device Figure 1 is a schematic diagram showing the configuration of the hydrogen sulfide detection device 10 according to this embodiment. The hydrogen sulfide detection device 10 is applied to a battery pack that houses battery cells having a sulfide electrolyte and detects the generation of hydrogen sulfide. The hydrogen sulfide detection device 10 may be housed together with the battery cells in the battery pack. The battery cells having a sulfide electrolyte are typically all-solid-state batteries using a solid sulfide electrolyte. The form of the battery cell is not particularly limited. For example, the form of the battery cell may be laminated or rectangular. All-solid-state batteries using sulfide electrolytes have high capacity and high output and are suitable for vehicle batteries. Therefore, the battery pack to which the hydrogen sulfide detection device 10 is applied may be a battery mounted in a vehicle.

[0013] The hydrogen sulfide detection device 10 includes a monitoring circuit 100 and a substrate 200. The substrate 200 is a printed circuit board (PCB) having a pattern 220 formed of metal. The substrate 200 may particularly be a flexible printed circuit (FPC). The pattern 220 of the substrate 200 forms a wiring (hereinafter also simply referred to as wiring) that electrically connects the first node 401 and the second node 402.

[0014] The monitoring circuit 100 and the substrate 200 are each connected to an external device via connectors 110 and 210. In the hydrogen sulfide detection device 10 shown in FIG. 1, the monitoring circuit 100 and the substrate 200 are directly connected by the connectors 110 and 210.

[0015] The monitoring circuit 100 monitors the voltage between the first node 401 and the second node 402. In the monitoring circuit 100, the first node 401 is connected to a power supply with a voltage Vcc (for example, 5V) via a resistor 120, and the second node 402 is connected to a ground GND with a reference potential (for example, 0V). The monitoring circuit 100 includes a monitoring processing unit 130. The monitoring processing unit 130 is a computer that executes a process of monitoring the voltage. The monitoring processing unit 130 may be realized by a microcontroller. The monitoring processing unit 130 is arranged so that the potential between the resistor 120 and the first node 401 is input. For example, when the monitoring processing unit 130 is a microcontroller, the input port of the microcontroller is connected between the resistor 120 and the first node 401. The resistor 120 serves as a pull-up resistor for the monitoring processing unit 130. For example, the resistance value of the resistor 120 is about 10 kΩ. The monitoring circuit 100 constitutes a voltage dividing circuit, and the monitoring processing unit 130 can detect the voltage between the first node 401 and the second node 402.

[0016] Note that the configuration of the monitoring circuit 100 shown in Figure 1 is just one example, and the monitoring circuit 100 can employ other configurations. For example, the voltage between the first node 401 and the second node 402 can be indirectly detected by measuring the voltage across the resistor 120. That is, monitoring the voltage between the first node 401 and the second node 402 includes monitoring the voltage across the resistor 120. Therefore, the monitoring processing unit 130 may be configured to measure the voltage across the resistor 120. Alternatively, for example, the monitoring circuit 100 can be configured such that the resistor 120 acts as a pull-down resistor for the monitoring processing unit 130. That is, the first node 401 may be directly connected to the power supply, and the second node 402 may be connected to ground GND via the resistor. The monitoring processing unit 130 may then be configured to detect the voltage between the first node 401 and the second node 402. For example, the input port of a microcontroller may be connected between the resistor and the second node 402.

[0017] The monitoring and processing unit 130 includes one or more processors 131 (hereinafter simply referred to as processor 131) and one or more storage devices 132 (hereinafter simply referred to as storage devices 132). The processor 131 executes various processes. The processor 131 is composed of, for example, a general-purpose processor, a special-purpose processor, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), an integrated circuit, a conventional circuit, and one or more combinations thereof. The processor 131 can also be called processing circuitry. The storage device 132 stores various information necessary for the execution of processes by the processor 131. The storage device 132 is composed of, for example, a recording medium such as RAM (Random Access Memory), ROM (Read Only Memory), SSD (Solid State Drive), HDD (Hard Disk Drive), etc. The storage device 132 stores computer programs that can be executed by the processor 131. The computer program consists of multiple instruction codes that describe the processes to be executed by the processor 131. The computer program is recorded on a computer-readable recording medium. The functions of the monitoring processing unit 130 are realized through the cooperation of the processor 131, which executes the computer program, and the storage device 132.

[0018] The metal used to form the pattern 220 on the substrate 200 is a metal that corrodes when it reacts with hydrogen sulfide. For example, copper or silver can be used as the metal. Furthermore, the substrate 200 has a detection unit 300 for detecting hydrogen sulfide. The configuration of the detection unit 300 will be described below with reference to Figure 2.

[0019] Figure 2 is a cross-sectional view showing a cross-section of the detection section 300 of the substrate 200. In the detection section 300, the substrate 200 has a two-layer structure in which patterns 220 are formed on both sides of the base material 230. When the substrate 200 is constructed as an FPC, polyimide or liquid crystal polymer can be used as the base material 230. However, the substrate 200 may also be constructed as a rigid substrate. In this case, paper phenol, paper epoxy, glass epoxy, etc. can be used as the base material 230.

[0020] In the detection unit 300, the pattern 220 includes at least one via 221, forming a single current path that crosses layers via the via 221. In the example shown in Figure 2, the pattern 220 includes four vias 221, forming a current path that crosses layers four times via the vias 221. Each via 221 is hollow, and its inner wall surface is plated with the same metal as the pattern 220.

[0021] Both sides of the substrate 200 are coated with a surface protection material 240 (e.g., coverlay, solder resist) using an adhesive 260. However, as shown in Figure 2, one surface of the substrate 200 has a recess 201 where the surface protection material 240 coating is not applied. Each via 221 of the pattern 220 is exposed to the outside of the substrate 200 through the recess 201. In other words, one surface of the substrate 200 is coated with the surface protection material 240 such that the positions of each via 221 of the pattern 220 are the recesses 201. Hereafter, the surface of the substrate 200 on the side where the recess 201 exists will be referred to as the "first surface," and the surface opposite the first surface will be referred to as the "second surface." In particular, the hydrogen sulfide detection device 10 is positioned so that the first surface faces vertically upward. That is, the recess 201 opens vertically upward.

[0022] In the detection unit 300, a reinforcing plate 250 is further attached to the second surface of the substrate 200 using adhesive 260 in the area where the pattern 220 is formed. The vias 221 of the pattern 220 are prone to breakage due to physical external forces. Therefore, the reinforcing plate 250 can improve the resistance of the detection unit 300 to vibration and shock.

[0023] The detection unit 300 of the substrate 200 is configured in this way. As described above, the pattern 220 of the detection unit 300 forms a single current path that spans layers via 221. Therefore, the wiring connecting the first node 401 and the second node also forms a single current path. In the example shown in Figure 2, the substrate 200 was partially a two-layer structure in the detection unit 300. However, the substrate 200 may be configured as a two-layer structure overall. Alternatively, the substrate 200 may be configured as a multilayer structure of three or more layers. In any case, the substrate 200 has a first surface on which the recess 201 exists, and each via 221 of the pattern 220 is configured to be exposed to the outside of the substrate 200 via the recess 201.

[0024] As described above, the hydrogen sulfide detection device 10 according to this embodiment is configured as described. Below, the operation of the hydrogen sulfide detection device 10 described above will be explained in detail.

[0025] 2. Operation of the hydrogen sulfide detection device Figure 3 is a schematic diagram illustrating the operation of the hydrogen sulfide detection device 10. Figure 2(A) shows the operation when the target battery pack is functioning normally. In other words, it shows the operation when no hydrogen sulfide is being generated from the battery cells. Under normal conditions, the pattern 220 of the detection unit 300 is conductive, and the wiring simply becomes a current path with no resistance. Therefore, the monitoring and processing unit 130 acquires the reference potential of ground GND as the detected value.

[0026] Figure 2(B) shows the operation during an abnormal situation, i.e., when hydrogen sulfide is generated from the battery cell. At this time, the hydrogen sulfide gas flows into the via 221 through the recess 201. As a result, the metal of the via 221 reacts with the incoming hydrogen sulfide and corrodes. When the metal corrodes into sulfides, the resistance value of the detection unit 300 increases. Furthermore, the metal tends to move radially due to corrosion. The corroded metal also moves when vibration is applied. For example, the corrosion of the vehicle is transmitted, causing the corroded metal to move. As corrosion progresses in this way, the metal of the via 221 gradually disappears. This causes the resistance value of the detection unit 300 to increase further. Finally, the pattern 220 of the detection unit 300 breaks. Moreover, according to this embodiment, the recess 201 opens vertically upward and hydrogen sulfide is heavier than air, so the incoming hydrogen sulfide remains inside the via 221. Therefore, the corrosion of the metal of the via 221 can be accelerated.

[0027] As the resistance of the detection unit 300 increases, the monitoring and processing unit 130 acquires the voltage division due to the resistance of the detection unit 300 as a detected value. In other words, as the resistance of the detection unit 300 increases, the detected value of the monitoring and processing unit 130 rises from the reference potential. Finally, when the pattern 220 of the detection unit 300 is broken, the power supply voltage Vcc is input directly to the monitoring and processing unit 130. That is, the monitoring and processing unit 130 acquires the power supply voltage Vcc as a detected value.

[0028] When hydrogen sulfide is generated from the battery cell in this way, the detection state of the detection unit 300 is expressed as the voltage between the first node 401 and the second node 402. That is, when hydrogen sulfide is generated from the battery cell, the detected value of the monitoring and processing unit 130 changes from the reference potential to Vcc. Therefore, the monitoring and processing unit 130 can determine whether or not hydrogen sulfide is being generated from the battery cell based on the change in the detected value (voltage between the first node 401 and the second node 402). For example, the monitoring and processing unit 130 may determine that hydrogen sulfide is being generated from the battery cell when the amount of change in the detected value from its initial value exceeds a threshold. Alternatively, the monitoring and processing unit 130 may use the detected value as is without calculating the amount of change in the detected value, and determine that hydrogen sulfide is being generated from the battery cell when the detected value exceeds a threshold.

[0029] Figure 4 is a flowchart showing the processing flow of the monitoring circuit 100 (more specifically, the monitoring processing unit 130). The processing flow shown in Figure 4 is executed repeatedly at predetermined processing cycles.

[0030] First, in step S110, the monitoring circuit 100 acquires the detected value. Next, in step S120, the monitoring circuit 100 calculates the amount of change from the initial value of the detected value. In the monitoring circuit 100 described above, the initial value of the detected value is the reference potential, and the amount of change from the initial value is the difference between the detected value and the reference potential. In particular, when the reference potential is 0V, the amount of change from the initial value matches the detected value. Next, in step S130, the monitoring circuit 100 determines whether the calculated amount of change is greater than a threshold.

[0031] If the fluctuation amount is below the threshold (step S130; No), the monitoring circuit 100 terminates the process, determining that no hydrogen sulfide is being generated. If the fluctuation amount is greater than the threshold (step S130; Yes), the monitoring circuit 100 determines that hydrogen sulfide is being generated from the battery cell (step S140). The monitoring circuit 100 may further execute a process to warn the user (e.g., vehicle driver) that hydrogen sulfide is being generated by display or sound.

[0032] In this embodiment, magnetic noise may be superimposed on the pattern of the detection unit 300. Therefore, it is desirable to reflect the detection error due to magnetic noise in the threshold value. Also, the processing flow shown in Figure 4 is just one example, and the monitoring circuit 100 can also determine whether hydrogen sulfide is being generated from the battery cell using other processing flows. For example, as described above, the monitoring circuit 100 may be configured to determine whether hydrogen sulfide is being generated from the battery cell by using the detected value directly without calculating the amount of fluctuation in the detected value. In this case, the processing related to step S120 in the processing flow shown in Figure 4 is skipped. In step S130, it is determined whether the detected value is greater than the threshold value. If the detected value is greater than the threshold value, the monitoring circuit 100 should determine that hydrogen sulfide is being generated from the battery cell.

[0033] 3. Via arrangement in the detection unit In the detection unit 300, the detection accuracy can be improved by increasing the number of vias 221 in pattern 220. However, it should be noted that increasing the number of vias 221 may lead to a decrease in vibration and shock resistance, an increase in cost, etc. When pattern 220 in the detection unit 300 contains two or more vias 221, various arrangements of vias 221 can be considered. Figure 5 is a schematic diagram showing an example of via arrangement when pattern 220 in the detection unit 300 contains four vias 221.

[0034] 3.1 Example 1 Figure 5(A) is a schematic diagram showing a first example of the arrangement of vias 221. Figure 5(A) is a top view of the detection unit 300 as seen from the first surface side. In Figure 5(A), the dashed lines indicate the pattern 220 that spans across layers to the second surface via the vias 221. In the first example, the four vias 221 (221-1, 221-2, 221-3, 221-4) are arranged in a grid. In particular, the arrangement of the four vias 221 is such that the creepage distance between two of the four vias 221 is greater than the diameter w of each via 221. For example, the creepage distance d between via 221-1 and via 221-414 is larger than w. Similarly, the creepage distance d 12 , d 23 , d 34 , d 13 , d 24 is larger than w.

[0035] When the metal of via 221 corrodes, the sulfide generated by the corrosion moves so as to ooze out to the first surface. Since the sulfide has conductivity, if two vias 221 are connected by the oozed sulfide, the two vias 221 will be short-circuited. Then, even if the corrosion of the metal of via 221 progresses, the pattern 220 of the detection unit 300 may remain in a conductive state, and there is a possibility that the generation of hydrogen sulfide cannot be detected. Therefore, it is important to ensure the creepage distance between two vias 221.

[0036] As shown in the first example, by making the creepage distance between two of the four vias 221 larger than the diameter w of each via 221, the creepage distance between the two vias 221 can be sufficiently ensured. As a result, it is possible to prevent a situation where the two vias 221 are short-circuited and hydrogen sulfide cannot be detected. Similarly, by arranging the vias 221 in the same way even when the pattern 220 includes more than four vias 221, the creepage distance can be sufficiently ensured. Generalizing the case where the pattern 220 includes N vias 221, the creepage distance d ij between the first via 221-i (i = 1, ···, N) and the second via 221-j (j = 1, ···, N, i ≠ j) i and the diameter w of the second via 221-j j should be made larger than that.

[0037] Also, the total amount of sulfide oozing out from the via 221 depends on the total amount of metal used for the via 221. Therefore, the creepage distance between two vias 221 can also be determined from simulation and actual experimental results. As an example, the creepage distance can be set to 5 mm or more.

[0038] 3.2 Second example Figure 5(B) is a schematic diagram showing a second example of the arrangement of vias 221. Figure 5(B), like (A), is a top view of the detection unit 300 seen from the first surface side. Also, like (A), the dashed lines show the pattern 220 that spans across layers to the second surface via the vias 221. In the second example, the four vias 221 (221-1, 221-2, 221-3, 221-4) are arranged in a straight line. In the second example as well, in order to ensure sufficient creepage distance, the arrangement of the four vias 221 is such that the creepage distance between two of the four vias 221 is greater than the diameter w of each via 221. Specifically, the creepage distance d 12 d 23 d 34 It is greater than w.

[0039] Figure 5 shows an example of via 221 arrangement; other patterns of via 221 arrangement are also possible.

[0040] 4. Effects As described above, the hydrogen sulfide detection device 10 according to this embodiment can detect the generation of hydrogen sulfide from a battery cell. In particular, according to the hydrogen sulfide detection device 10 described above, hydrogen sulfide gas flows into the via 221 through the recess 201 on the first surface of the substrate 200, and the generation of hydrogen sulfide is detected by the corrosion of the metal of the via 221. Since the incoming hydrogen sulfide remains inside the via 221, even if only a small amount of hydrogen sulfide flows in, the corrosion of the metal of the via 221 progresses rapidly. Thus, the hydrogen sulfide detection device 10 according to this embodiment can detect the generation of hydrogen sulfide with high accuracy. Furthermore, it is possible to construct the hydrogen sulfide detection device 10 by reusing an existing substrate used for monitoring the voltage of a battery cell, etc. This makes it possible to construct the hydrogen sulfide detection device 10 at low cost.

[0041] Furthermore, according to this embodiment, the substrate 200 is arranged so that its first surface faces vertically upward. That is, the recess 201 opens vertically upward. Since hydrogen sulfide is heavier than air, this makes it easier for hydrogen sulfide to accumulate inside the via 221. As a result, the detection accuracy of the hydrogen sulfide detection device 10 can be further improved.

[0042] Furthermore, according to this embodiment, in the detection unit 300, a reinforcing plate 250 is attached to the portion of the second surface of the substrate 200 where the pattern 220 is formed. This improves the resistance of the detection unit 300 to vibration and shock. In addition, the reinforcing plate 250 may be fixed to the battery cell or end plate, etc. This makes it possible to reduce physical damage caused by vibration and shock.

[0043] Furthermore, in this embodiment, by making the plating on the inner wall surface of the via 221 appropriately thin, the progression of metal corrosion of the via 221 can be accelerated. As a result, the detection accuracy of the hydrogen sulfide detection device 10 can be further improved.

[0044] Furthermore, in order to quickly detect hydrogen sulfide generated from the battery cells, the substrate 200 of the hydrogen sulfide detection device 10 may be arranged such that the vias 221 face the battery cells. Figure 6 is a schematic diagram showing an example of the arrangement of the substrate 200 of the hydrogen sulfide detection device 10. A battery cell 20 is schematically shown in Figure 6. In the example shown in Figure 6, the substrate 200 is arranged such that the vias 221 face the battery cells 20. By positioning the vias 221 facing the battery cells 20 in this way, hydrogen sulfide can easily flow into the vias 221. As a result, the detection accuracy of the hydrogen sulfide detection device 10 can be further improved. Also, since hydrogen sulfide gas is heavier than air, the detection accuracy can be further improved by placing the substrate 200 at the bottom of the battery pack. In addition, in order to detect the generation of hydrogen sulfide at multiple locations within the battery pack, it is also effective to place the substrate 200 at multiple locations within the battery pack. [Explanation of Symbols]

[0045] 10. Hydrogen sulfide detection device 20 battery cells 100 Supervisory circuit 200 circuit boards 201 Recess 220 patterns 221 Beer 401 Node 1 402 Node 2

Claims

1. A hydrogen sulfide detection device applied to a battery pack containing a battery cell having a sulfide-based electrolyte, Wiring to electrically connect the first node and the second node, A monitoring circuit that monitors the voltage between the first node and the second node, Equipped with, The aforementioned wiring includes a pattern formed on a substrate and made of a metal that corrodes in reaction with hydrogen sulfide. The aforementioned pattern includes at least one via, The surface of the substrate has a recess, Each of the at least one via is exposed to the outside of the substrate through the recess. Hydrogen sulfide detection device.

2. A hydrogen sulfide detection device according to claim 1, The at least one via includes a first via and a second via that are spaced apart. The creepage distance between the first via and the second via is greater than the diameter of the first via and the diameter of the second via. Hydrogen sulfide detection device.

3. A hydrogen sulfide detection device according to claim 1, The at least one via is positioned opposite the battery cell. Hydrogen sulfide detection device.

4. A hydrogen sulfide detection device according to claim 1, The recess opens vertically upward. Hydrogen sulfide detection device.

5. A hydrogen sulfide detection device according to any one of claims 1 to 4, The monitoring circuit determines whether or not hydrogen sulfide is being generated from the battery cell based on the change in voltage. Hydrogen sulfide detection device.

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