Battery system

Abstract

To avoid a situation where a battery system overreacts to a hydrogen sulfide gas from a sulfide-based all-solid battery.SOLUTION: A battery system includes a battery unit 105, a heater unit 121, and a sensor unit 110. The battery unit 105 is housed in a battery case 102 and includes a sulfide-based all-solid battery. The heater unit 121 is configured to heat the battery unit 105. The sensor unit 110 is configured to measure a hydrogen sulfide gas concentration in the battery case 102. Driving of the heater unit 121 is started when a measured value of the sensor unit 110 exceeds a first threshold value. In a case that the measured value exceeds a second threshold value higher than the first threshold value after the driving of the heater unit 121 is started, handling control for handling occurrence of a hydrogen sulfide gas from the sulfide-based all-solid battery is carried out.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a battery system.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2022-46077 (Patent Document 1) discloses a battery system including a secondary battery, a sensor, and a control device. The secondary battery may be a sulfide-based all-solid-state battery and is housed in a battery case. The sensor is, for example, a hydrogen sulfide concentration meter and detects (measures) the hydrogen sulfide gas concentration in the battery case. When the detected value of the sensor is higher than a threshold value, the control device determines that hydrogen sulfide is being generated from the secondary battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A sulfide-based all-solid-state battery can generate hydrogen sulfide gas inside a battery case. Although hydrogen sulfide gas may be present inside the battery case, there may also be miscellaneous gases different from hydrogen sulfide gas. If the above sensor reacts to the miscellaneous gases, the measurement error of the sensor may increase. As a result, although hydrogen sulfide is not actually being generated from the sulfide-based all-solid-state battery, the measured value of the sensor may exceed the threshold value. In this case, it may be erroneously determined that hydrogen sulfide gas is being generated from the sulfide-based all-solid-state battery. As a result, unnecessary control may be executed, and there is a possibility of overresponding to hydrogen sulfide gas from the sulfide-based all-solid-state battery.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to avoid a situation of overresponding to hydrogen sulfide gas from a sulfide-based all-solid-state battery. [Means for solving the problem]

[0006] The battery system of this disclosure comprises a battery unit, a heater unit, and a sensor unit. The battery unit is housed in a battery case and includes a sulfide-based all-solid-state battery. The heater unit is configured to heat the battery unit. The sensor unit is configured to measure the hydrogen sulfide gas concentration in the battery case. The heater unit is activated when the measurement value from the sensor unit exceeds a first threshold. If the measurement value exceeds a second threshold higher than the first threshold after the heater unit has been activated, response control is performed to address the generation of hydrogen sulfide gas from the sulfide-based all-solid-state battery.

[0007] According to this disclosure, it is possible to avoid situations where hydrogen sulfide gas from sulfide-based all-solid-state batteries is over-reacted to. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram schematically shows the overall configuration of a vehicle equipped with a battery system according to the present invention. [Figure 2] This diagram schematically shows each cell in a battery pack of a battery unit. [Figure 3] This diagram illustrates the connection relationships between the battery unit, the SMR (System Main Relay), and the drive unit. [Figure 4] This is a perspective view of the battery case and battery unit. [Figure 5] This is the AA section in Figure 4. [Figure 6] This flowchart illustrates the processing and control performed by the ECU (Electronic Control Unit) in the embodiment. [Figure 7] This flowchart illustrates the processing and control performed by the ECU in the modified example. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described in detail below with reference to the drawings. The same or corresponding parts in the drawings will be denoted by the same reference numerals and their descriptions will not be repeated. Each embodiment and its modifications may be combined with one another as appropriate.

[0010] Figure 1 is a schematic diagram showing the overall configuration of a vehicle equipped with a battery system according to the present embodiment. This vehicle is, for example, an electric vehicle (BEV), but may also be other types of electric vehicles such as a hybrid electric vehicle (HEV) equipped with an engine.

[0011] Referring to Figure 1, Vehicle 1 comprises a battery case 102, a battery unit 105, a sensor unit 110, an SMR 112, a drive unit 115, a drive wheel 119, a heater unit 121, an HMI (Human Machine Interface) device 122, and an ECU 170. The battery case 102, battery unit 105, sensor unit 110, SMR 112, heater unit 121, HMI device 122, and ECU 170 form the “battery system” of this disclosure.

[0012] The battery case 102 houses the battery unit 105. The battery unit 105 is configured to be rechargeable and dischargeable and stores power for the vehicle 1 to run. The battery unit 105 includes a sulfide-based all-solid-state battery. An all-solid-state battery is a battery in which the electrolyte layer is solid. A sulfide-based all-solid-state battery is an all-solid-state battery in which at least one of the materials of the positive electrode active material layer of the battery unit 105 or the materials of the solid electrolyte layer of the battery unit 105 contains a sulfur component. The battery unit 105 includes a plurality (two in this example) of battery packs.

[0013] Figure 2 is a schematic diagram showing each cell of the battery pack of battery unit 105. Referring to Figure 2, each cell 52 includes a laminate film 45, an electrode body 46, a positive electrode tab 47, and a negative electrode tab 48. The electrode body 46 is sealed within the laminate film 45. The positive electrode tab 47 and the negative electrode tab 48 are connected to the electrode body 46 and are drawn out from inside to outside the laminate film 45. Each cell 52 is a sulfide-based all-solid-state battery.

[0014] Repeated charging and discharging of the battery unit 105 can generate hydrogen sulfide gas within the battery cell 25. For example, a gap may form in the area where the positive electrode tab 47 and negative electrode tab 48 are drawn out from the laminate film 45, allowing air to enter the laminate film 45 through this gap. As a result, the solid electrolyte layer may react with water in the air to generate hydrogen sulfide gas. Alternatively, an internal short circuit may occur within the electrode body 46, causing the electrode body 46 to become hot and generating hydrogen sulfide gas. Thus, sulfide-based all-solid-state batteries can generate hydrogen sulfide gas themselves. This generation of hydrogen sulfide gas is unique to sulfide-based all-solid-state batteries and is promoted as the cell temperature rises (the higher the cell temperature, the greater the amount of hydrogen sulfide gas generated).

[0015] Figure 3 is a diagram illustrating the connection relationship between the battery unit 105, the SMR 112, and the drive unit 115. Referring to Figure 3, the battery unit 105 is configured to be connectable to the drive unit 115 via the SMR 112. Organic solvents may be present outside the battery unit 105. The battery case 102 houses the battery unit 105 as well as components made of various chemical materials, including silicone rubber.

[0016] The SMR112 is connected between the battery unit 105 and the drive unit 115. Closing the SMR112 is equivalent to turning on the vehicle 1's driving system. Opening the SMR112 is equivalent to turning off the vehicle 1's driving system.

[0017] Referring to FIG. 1 again, the sensor unit 110 includes sensors 55A and 55B. Each of the sensors 55A and 55B is configured to measure the concentration of hydrogen sulfide (H2S) gas in the battery case 102. The measured values of the sensors 55A and 55B are also represented as measured values MVA and MVB, respectively. Each sensor may also react to a gas different from hydrogen sulfide gas (impurity gas). That is, each of the measured values MVA and MVB may be affected by the impurity gas.

[0018] The drive unit 115 includes a PCU (Power Control Unit) 116 and a rotating electric machine 118 (see FIG. 3). The PCU 116 is connected to the rotating electric machine 118. The PCU 116 is a power conversion device that converts the DC power supplied from the battery unit 105 via the SMR 112 into AC power and supplies the AC power to the rotating electric machine 118. The rotating electric machine 118 is connected to the drive wheels 119 and generates a driving force (travel driving force) of the vehicle 1 by receiving the AC power from the PCU 116. The heater unit 121 includes a plurality of (two in this example) heaters and is configured to heat the battery unit 105.

[0019] The HMI device 122 is a touch screen and functions as an informing device that receives various operations from the user of the vehicle 1 and informs the user by displaying various screens.

[0020] The ECU 170 includes a processor 171, a memory 172, and a storage device 173. The processor 171 is, for example, a CPU (Central Processing Unit) and executes various arithmetic processes. The memory 172 includes a ROM (Read Only Memory) and a RAM (Random Access Memory) (both not shown). The ROM stores programs executed by the processor 171. The storage device 173 stores various data.

[0021] The ECU 170 controls various devices of the vehicle 1, such as the SMR 112, the PCU 116, the heater unit 121, the HMI device 122, and an electromagnetic on-off valve (described later). The ECU 170 opens and closes the SMR 112. The ECU 170 controls the charging power and discharging power of the battery unit 105 by controlling the PCU 116. The ECU 150 sets the upper limit of the charging power and the upper limit of the discharging power. The ECU 150 can limit the charging power and the discharging power respectively by reducing these upper limits. When the charging power and the discharging power (charging and discharging of the battery unit 105) are limited, the generation of hydrogen sulfide gas is suppressed.

[0022] The ECU 170 determines whether hydrogen sulfide gas is generated from the battery unit 105 in the battery case 102 according to the measured values MVA and MVB. For example, when both of the measured values MVA and MVB are less than a predetermined threshold value (described later), the ECU 170 determines that no hydrogen sulfide gas is generated in the battery case 102. On the other hand, when at least one of the measured values MVA and MVB is greater than or equal to the above threshold, the ECU 170 determines that hydrogen sulfide gas is generated in the battery case 102. In this case, the ECU 170 executes corresponding control (specifically described later) for coping with the generation of hydrogen sulfide gas from the battery unit 105.

[0023] FIG. 4 is a perspective view of the battery case 102 and the battery unit 105. Referring to FIG. 4, the battery case 102 houses two battery packs 50 (batteries 50A and 50B) included in the battery unit 105. The battery case 102 includes a lower case 91 and an upper case 92. A breathing film 61 is provided on the upper case 92.

[0024] The heater unit 121 includes heaters 30A and 30B. The heaters 30A and 30B are respectively disposed below the batteries 50A and 50B. The heaters 30A and 30B heat the batteries 50A and 50B respectively.

[0025] Sensors 55A and 55B are located near batteries 50A and 50B, respectively. In other words, sensor 55A is closer to battery 50A than sensor 55B, and sensor 55B is closer to battery 50B than sensor 55A.

[0026] Figure 5 is a cross-section of AA in Figure 4. Referring to Figure 5, the battery pack 50 (battery 50B in this example) contains multiple cells 52. The multiple cells 52 and the heater 30B are located between the end plates 31, 32. The sensor 55B is located on the bottom surface of the lower case 91. This is because hydrogen sulfide gas is heavier than air.

[0027] The duct 60 is provided in the battery case 102 (upper case 92) and is a passage that connects the inside and outside of the battery case 102. The duct 60 is provided with breathing membranes 61 and 62. Each of the breathing membranes 61 and 62 is made of a breathable waterproof material. This material is, for example, GORE-TEX (registered trademark). The internal space of the battery case 102 is almost sealed, but it is not completely sealed because the breathing membranes 61 and 62 are provided in the duct 60. A desulfurizing agent 63 is placed inside the duct 60.

[0028] When the pressure inside the battery case 102 increases, air is discharged from the inside to the outside of the battery case 102 through the duct 60 and breathing membranes 61 and 62. If hydrogen sulfide gas is present inside the battery case 102, the desulfurizing agent 63 adsorbs and purifies the hydrogen sulfide gas flowing from the inside to the outside of the battery case 102. On the other hand, when the pressure inside the battery case 102 decreases, air flows in from the outside to the inside of the battery case 102 through the duct 60 and breathing membranes 61 and 62.

[0029] A solenoid valve 65 is provided in the duct 60. The opening degree of the solenoid valve 65 is adjusted according to a command from the ECU 170. By adjusting this opening degree, the duct 60 can be opened or closed. Both the duct 60 and the solenoid valve 65 are included in the aforementioned battery system.

[0030] As mentioned above, the battery unit 105 (sulfide-based all-solid-state battery) may generate hydrogen sulfide gas within the battery case 102. Although hydrogen sulfide gas may be present within the battery case 102, other miscellaneous gases may also be present. This is because the air flowing into the battery case 102 from the outside through the duct 60 may contain miscellaneous gases, or miscellaneous gases may be generated from the various materials contained within the battery case 102, organic solvents outside the battery unit 105 (battery pack 50), or the constituent materials of the breathing membranes 61 and 62.

[0031] Sensors 55A and 55B can react to unwanted gases. In this case, the measurement error included in the measured values ​​MVA and MVB may increase. As a result, even though hydrogen sulfide is not actually being generated from the battery unit 105, at least one of the measured values ​​MVA and MVB may exceed the aforementioned threshold. Therefore, it may be mistakenly determined that hydrogen sulfide gas is being generated from the battery unit 105. Consequently, unnecessary control may be executed, and an overreaction to hydrogen sulfide gas may occur. To avoid the above misjudgment, it would seem preferable to mount a high-precision hydrogen sulfide gas concentration sensor with low reactivity to unwanted gases (capable of accurately measuring only hydrogen sulfide gas) on the vehicle 1. However, this would increase costs.

[0032] In this embodiment, the ECU 170 has a configuration to address the above-mentioned problem. Specifically, the ECU 170 starts driving the heater unit 121 (for example, both heaters 30A and 30B) when at least one of the measured values ​​MVA and MVB exceeds a first threshold. After the heater unit 121 is started, if neither of the measured values ​​MVA or MVB exceeds a second threshold, the ECU 170 determines that no hydrogen sulfide gas is being generated from the battery unit 105 in the battery case 102. On the other hand, if at least one of the measured values ​​MVA or MVB exceeds the second threshold, the ECU 170 determines that hydrogen sulfide gas is being generated from the battery unit 105 in the battery case 102. Based on this determination, the ECU 170 performs corresponding control (details will be described later) to address the generation of hydrogen sulfide gas from the battery unit 105. The second threshold is higher than the first threshold.

[0033] With this configuration, if the battery unit 105 is actually generating hydrogen sulfide gas, the generation of hydrogen sulfide gas is accelerated after the heater unit 121 starts operating due to the heating of the battery unit 105 (increase in cell temperature). As a result, the amount of hydrogen sulfide gas generated from the battery unit 105 increases, and the hydrogen sulfide gas concentration in the battery case 102 rises further. Consequently, at least one of the measured values ​​MVA and MVB exceeds the second threshold. On the other hand, the concentration of impurities gas in the battery case 102 is unrelated to the temperature rise of the battery unit 105 and therefore does not rise in response to the start of operation of the heater unit 121. With the above configuration, it is possible to avoid situations in which it is incorrectly determined that hydrogen sulfide gas is being generated. Furthermore, a highly accurate hydrogen sulfide gas concentration sensor is not necessarily required. In addition, it is possible to avoid situations in which the response control is unnecessarily started due to the reaction of sensors 55A and 55B to impurities gas. Therefore, it is possible to avoid situations in which the system overreacts to hydrogen sulfide gas from the battery unit 105.

[0034] The following describes an example of corresponding control. The corresponding control includes at least one of the following: opening the SMR112 (turning off the driving system), opening the electromagnetic valve 65, controlling the HMI device 122 to notify the user of the generation of hydrogen sulfide gas in the battery case 102, and controlling the PCU 116 to limit the charging and discharging of the battery unit 105.

[0035] Opening the SMR112 disconnects the battery unit 105 from the PCU116. This electrically isolates the battery unit 105, cutting off its connection to other components of the vehicle 1. As a result, charging and discharging are stopped (the vehicle 1 stops), and the generation of hydrogen sulfide gas is suppressed. Opening the electromagnetic valve 65 allows hydrogen sulfide gas to be discharged from inside the battery case 102 to the outside through the duct 60. Controlling the HMI device 122 as described above notifies the user of the generation of hydrogen sulfide gas. This motivates the user to take action to address the generation of hydrogen sulfide gas (for example, by using the vehicle 1 maintenance service). Controlling the PCU116 as described above limits the charging and discharging of the battery unit 105. This suppresses the generation of hydrogen sulfide gas. Thus, the corresponding control can address the generation of hydrogen sulfide gas inside the battery case 102.

[0036] The first threshold is, for example, 1 ppm or less (1 ppm = 0.0001%). The second threshold is, for example, higher than 1 ppm and less than 5 ppm. In this embodiment, the first threshold is 1 ppm and the second threshold is 3 ppm.

[0037] Generally, the control concentration and permissible concentration of hydrogen sulfide gas are considered to be 1 ppm and 5 ppm, respectively. With the above configuration, even if at least one of the measured values ​​MVA and MVB exceeds the second threshold (3 ppm) after the heater unit 121 starts operating, it is possible to avoid a situation where the hydrogen sulfide gas concentration exceeds the permissible concentration (5 ppm). As a result, it is possible to accurately determine whether hydrogen sulfide gas is generated or not without the hydrogen sulfide gas concentration exceeding the permissible concentration.

[0038] Figure 6 is a flowchart illustrating the processing and control performed by the ECU170 in the embodiment. This flowchart is initiated when at least one of the measured values ​​MVA and MVB exceeds the threshold TH1. The threshold TH1 corresponds to the first threshold.

[0039] Referring to Figure 6, the ECU 170 starts driving the heater unit 121 (S110), and then determines whether at least one of the measured values ​​MVA and MVB exceeds the threshold TH2 (S115). The threshold TH2 corresponds to the second threshold.

[0040] If at least one of the measured values ​​MVA or MVB exceeds the threshold TH2 (YES in S115), the ECU 170 determines that hydrogen sulfide gas has been generated in the battery case 102 (S120) and executes the corresponding control described above (S125). On the other hand, if neither of the measured values ​​MVA or MVB exceeds the threshold TH2 (NO in S115), the ECU 170 determines that no hydrogen sulfide gas has been generated in the battery case 102 (S130). In this case, it is considered that the sensor unit 110 has simply reacted to some unwanted gas. After S125 or S130, the process ends.

[0041] As described above, according to this embodiment, the generation / non-generation of hydrogen sulfide gas can be determined with high accuracy. Furthermore, excessive response to hydrogen sulfide gas from the battery unit 105 can be avoided.

[0042] <Modified Example of Embodiment> Referring again to Figure 4, in this embodiment, the ECU 170 drives both heaters 30A and 30B, but from the viewpoint of reducing power consumption, only one of these heaters may be driven. In this modified example, if the measured value MVA exceeds the threshold TH1 earlier than the measured value MVB, the ECU 170 starts driving only heater 30A of heaters 30A and 30B.

[0043] As mentioned above, sensor 55A is located closer to battery 50A than sensor 55B. Therefore, if the measured value MVA exceeds threshold TH1 earlier than the measured value MVB, it is considered that the hydrogen sulfide gas is being generated from battery 50A and not battery 50B. Consequently, to promote the generation of hydrogen sulfide gas from battery 50A (battery unit 105), it is sufficient to start driving only heater 30A of heaters 30A and 30B, and it is not necessarily required to drive both heaters. By starting to drive only heater 30A as described above, power consumption in heater unit 121 can be reduced compared to the embodiment in which both heaters 30A and 30B are driven. Furthermore, after starting to drive heater 30A, the generation of hydrogen sulfide gas from battery 50A is promoted, and the measured value MVA may exceed threshold TH2. As a result, it is determined that the hydrogen sulfide gas is being generated from battery 50A, and corresponding control is executed.

[0044] Figure 7 is a flowchart illustrating the processing and control performed by the ECU170 in this modified example. This flowchart is initiated when either the measured value MVA or MVB exceeds the threshold TH1.

[0045] Referring to Figure 7, the ECU 170 determines whether the measured value MVA exceeded the threshold TH1 earlier than the measured value MVB, that is, whether the measured value that exceeded the threshold TH1 was the measured value MVA (S205).

[0046] If the measured value MVA exceeds threshold TH1 before the measured value MVB (YES in S205), the ECU 170 starts driving the heater 30A (S210), and then determines whether the measured value MVA has exceeded threshold TH2 (S215). If the measured value MVA does not exceed threshold TH2 (NO in S215), the ECU 170 determines that no hydrogen sulfide gas has been generated in the battery case 102 (S230). If the measured value MVA exceeds threshold TH2 (YES in S215), the ECU 170 determines that hydrogen sulfide gas has been generated (S220) and executes corresponding control (S225).

[0047] If the measured value MVB exceeds the threshold TH1 earlier than the measured value MVA, i.e., if the measured value that exceeded the threshold TH1 was the measured value MVB (NO in S205), the ECU 170 starts driving the heater 30B (S212). Next, the ECU 170 determines whether the measured value MVB has exceeded the threshold TH2 (S217). If the measured value MVB has exceeded the threshold TH2 (YES in S217), the process proceeds to S220. If the measured value MVB has not exceeded the threshold TH2 (NO in S217), the process proceeds to S230.

[0048] As described above, this modification makes it possible to reduce the power consumption of the heater unit 121.

[0049] <Other variations> Although the sensor unit 110 includes both sensors 55A and 55B, it may also include a single sensor that measures the concentration of hydrogen sulfide gas in the battery case 102 without including these two sensors. In this case, the ECU 170 starts driving the heater unit 121 (e.g., heater 30A) when the measurement value from this sensor exceeds the threshold TH1. After starting to drive the heater unit 121, the ECU 170 determines whether the measurement value exceeds the threshold TH2. If the measurement value does not exceed the threshold TH2, the ECU 170 determines that no hydrogen sulfide gas is being generated in the battery case 102. On the other hand, if the measurement value exceeds the threshold TH2, the ECU 170 determines that hydrogen sulfide gas has been generated and performs corresponding control.

[0050] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0051] 1 Vehicle, 30A, 30B heater, 50A, 50B battery, 55A, 55B sensor, 65 electromagnetic valve, 102 battery case, 105 battery unit, 110 sensor unit, 118 rotating electric machine, 121 heater unit, 122 HMI device, 170 ECU.

Claims

1. A battery system, Housed in a battery case, the battery unit includes a sulfide-based all-solid-state battery, A heater unit configured to heat the aforementioned battery unit, The battery case is equipped with a sensor unit configured to measure the hydrogen sulfide gas concentration inside the battery case, The heater unit is started to operate when the measurement value of the sensor unit exceeds a first threshold value. If the measured value exceeds a second threshold value that is higher than the first threshold value after the heater unit has started to operate, a corresponding control is performed to respond to the generation of hydrogen sulfide gas from the sulfide-based all-solid-state battery. The battery unit is configured to be rechargeable and dischargeable, and is configured to be connectable via a relay device to a power converter connected to a rotating electric machine that generates the propulsion force of an electric vehicle. The aforementioned battery system A communication passage that connects the inside and outside of the battery case, An on / off valve provided in the aforementioned communication passage, The vehicle further comprises a notification device that notifies the user of the electric vehicle, The aforementioned corresponding control is, Opening the aforementioned relay device, Opening the aforementioned shut-off valve, Controlling the notification device to notify the user of the generation of hydrogen sulfide gas inside the battery case, A battery system comprising at least one of the following: controlling the power converter such that the charging and discharging of the battery unit is limited.

2. The battery unit includes a first battery and a second battery, The heater unit includes a first heater for heating the first battery and a second heater for heating the second battery. The sensor unit includes a first sensor and a second sensor, each configured to measure the hydrogen sulfide gas concentration, wherein the first sensor is located near the first battery, and the second sensor is located near the second battery. The battery system according to claim 1, wherein if the measurement value of the first sensor exceeds the first threshold value earlier than the measurement value of the second sensor, only the first heater among the first and second heaters is started to operate.

3. The first threshold is 1 ppm or less. The battery system according to claim 1 or claim 2, wherein the second threshold is greater than 1 ppm and less than 5 ppm.

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