Method for inspecting battery airtightness and device for inspecting battery airtightness

Abstract

To provide a method and device for inspecting airtightness of a battery that can determine the airtightness of an all-solid battery by identifying leakage of hydrogen sulfide gas on the basis of a pressure difference of moisture vapor being supplied when inspecting the sealing performance (airtightness) of an all-solid battery.SOLUTION: A method for inspecting airtightness of a battery comprises: a step (ST1) of supplying moisture vapor-containing gas to the inside of a closed vessel in which a battery having a sulfide-based solid electrolyte is housed; a step (ST2) of setting a determination threshold value on the basis of information on a moisture vapor concentration contained in the moisture vapor-containing gas; a step (ST3) of detecting a hydrogen sulfide gas that is generated from the battery by supplying the vapor-containing gas to the battery; a step (ST4) of comparing a value related to the hydrogen sulfide gas detected with the determination threshold value; and a step (ST5, ST6) of determining the airtightness of the battery on the basis of the result of comparing the value related to the hydrogen sulfide gas with the determination threshold value.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for inspecting the airtightness of a battery and an apparatus for inspecting the airtightness of a battery.

Background Art

[0002] Patent Document 1 discloses an airtightness inspection apparatus capable of performing an airtightness inspection in a short time by detecting a gaseous detection target leaked from an inspection target.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the object to be inspected by the airtightness inspection apparatus in Patent Document 1 is a liquid-type lithium-ion battery. In the case of the liquid-type lithium-ion battery, gas leaks to the outside of the battery due to the volatilization and decomposition of the liquid electrolyte components.

[0005] However, for example, when a all-solid-state battery including a solid electrolyte is the inspection target, gas is not generated by the volatilization or the like of the electrolyte components. Therefore, when performing an airtightness inspection, it is not possible to adopt a method of inspecting the airtightness of a battery by detecting a gaseous detection target leaked from an inspection target using the method disclosed in Patent Document 1.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery airtightness inspection method and a battery airtightness inspection apparatus capable of determining the airtightness of a all-solid-state battery by grasping the leakage of hydrogen sulfide gas based on the partial pressure difference of water vapor supplied when inspecting the airtightness of the all-solid-state battery.

Means for Solving the Problem

[0007] The method for inspecting the airtightness of a battery in the embodiment includes a step of supplying a water vapor-containing gas into a sealed container in which a battery having a sulfide-based solid electrolyte is accommodated, a step of setting a determination threshold based on information on the water vapor concentration contained in the water vapor-containing gas, a step of detecting hydrogen sulfide gas generated from the battery when the water vapor-containing gas is supplied to the battery, a step of comparing a value related to the detected hydrogen sulfide gas with the determination threshold, and a step of determining the airtightness of the battery based on the result of comparing the value related to the hydrogen sulfide gas with the determination threshold.

Advantages of the Invention

[0008] Since the present invention adopts such a configuration, it is possible to provide a method for inspecting the airtightness of a battery and an apparatus for inspecting the airtightness of a battery, which can grasp the leakage of hydrogen sulfide gas based on the partial pressure difference of water vapor supplied when inspecting the airtightness of an all-solid-state battery and determine the airtightness of the all-solid-state battery.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that each drawing is schematic and may be different from the actual one. In addition, the embodiments of the present invention shown below are examples of devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention does not specify the structure, arrangement, etc. of the components as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

[0011] FIG. 1 is a block diagram showing the internal configuration of a battery airtightness inspection device A in an embodiment of the present invention. The airtightness inspection device A is a device used to inspect the airtightness of a packaging material of a battery B containing a battery element including a current collector and an electrolyte.

[0012] Here, the packaging material is, for example, made of a laminate film and is composed of a metal laminate film having a heat-sealing resin layer on the surface facing the inside of the battery B. More specifically, for example, two metal laminate films are overlapped to form a laminate film packaging material. Then, with a battery including, for example, a sulfide-based solid electrolyte housed inside, the outer periphery of the laminate film packaging material is heat-sealed, thereby sealing the inside.

[0013] Since the packaging material adopts such a configuration, it inherently has gas permeability, allowing gaseous substances to enter the battery B from the outside or be released from the inside of the battery B to the outside. Therefore, the airtightness inspection device A of the battery inspects whether gas permeation exceeding the preset level has occurred, that is, inspects the airtightness of the battery B to be inspected, especially using the gas released from the inside to the outside of the battery B.

[0014] Also, in the embodiments of the present invention, the battery B to be inspected for airtightness is, for example, a all-solid-state battery. A all-solid-state battery is a battery in which the electrolyte is formed of a solid, rather than using a liquid electrolyte like a conventional liquid lithium-ion battery. Also, as all-solid-state batteries, for example, batteries of various types of solid electrolytes such as sulfide-based and oxide-based can be considered. However, in the embodiments of the present invention, in particular, a all-solid-state battery using a sulfide-based solid electrolyte as the electrolyte is the object of the airtightness inspection.

[0015] The airtightness inspection device A includes a water vapor-containing gas supply device 1, a sealed container 2, a detection device 3, and a determination device 4. The water vapor-containing gas supply device 1 is a device that supplies a gas containing water vapor into the sealed container 2. Here, as the water vapor-containing gas, for example, in addition to a gas whose amount of water vapor is adjusted to a preset water vapor concentration, a gas whose water vapor concentration contained in the gas is unknown in advance may also be used. Note that as a gas with an unknown water vapor concentration like the latter gas, for example, air can be cited.

[0016] Also, the following devices may be provided in the water vapor-containing gas supply device 1. For example, each device that can be added to the water vapor-containing gas supply device 1 is shown at the lower part of the water vapor-containing gas supply device 1 in FIG. 1.

[0017] The flow rate measuring device 11 has a function of measuring the flow rate of the water vapor-containing gas supplied to the sealed container 2. As the flow rate measuring device 11, for example, a flow meter is used. Also, as long as the flow rate of the water vapor-containing gas can be measured, any measurement method may be used.

[0018] Further, the humidity adjusting device 12 has a function of adjusting the water vapor concentration contained in the water vapor-containing gas by adjusting the humidity of the water vapor-containing gas. As the humidity adjusting device 12, for example, a hygrometer is used, and the humidity information measured by the humidity adjusting device 12 is transmitted to, for example, the water vapor-containing gas supply device 1, thereby adjusting the humidity. Also, in addition to the hygrometer, when, for example, a device capable of adjusting the humidity is provided, the humidity adjusting device 12 may directly adjust the water vapor concentration contained in the water vapor-containing gas.

[0019] Furthermore, the flow rate adjusting device 13 has a function of adjusting the flow rate of the water vapor-containing gas supplied to the sealed container 2. By adjusting the flow rate, the water vapor concentration contained in the water vapor-containing gas can be kept constant. As the flow rate adjusting device 13, for example, a valve mechanism such as a flow rate adjusting valve is conceivable, and by adjusting the opening degree of the valve mechanism, the flow rate of the water vapor-containing gas supplied to the inside of the sealed container 2 is adjusted.

[0020] The sealed container 2 is a container that houses the battery B to be subjected to the airtightness inspection. In the airtightness inspection, it is necessary to determine whether or not the gas leaking from the inside of the battery B to the outside leaks more than a preset amount. Therefore, in order to avoid mixing of other gases with the gas leaking from the inside of the battery B to the outside (inside the sealed container 2), the container that houses the battery B is made airtight.

[0021] As described above, the sealed container 2 is a container that houses the battery B to be inspected, but the following devices may be provided. For example, each device that can be added to the sealed container 2 is shown at the lower part of the sealed container 2 in FIG. 1.

[0022] That is, for example, when the water vapor concentration in the supplied water vapor-containing gas is unknown, the water vapor concentration measuring device 21 measures the water vapor concentration contained in the supplied water vapor-containing gas. As will be described later, when the water vapor concentration contained in the supplied water vapor-containing gas is measured by the water vapor concentration measuring device 21, a determination threshold value necessary for determining the airtightness of the battery B to be inspected is set.

[0023] Note that the method for measuring the water vapor concentration may be any method. For example, the water vapor concentration can be calculated by measuring the partial pressure difference of the water vapor contained in the water vapor-containing gas. Also, for the device for measuring the water vapor concentration, any device can be adopted as long as it can grasp the water vapor concentration. Further, the information on the measured water vapor concentration is transmitted to the determination device 4. Additionally, the water vapor concentration measuring device 21 may be provided anywhere in the sealed container 2.

[0024] The temperature measuring device 22 is a device that measures the temperature inside the sealed container 2. Generally, when a chemical reaction proceeds, the reaction progresses faster at a higher temperature. Therefore, by measuring the temperature inside the sealed container 2, it is used when determining the threshold value used in the determination of airtightness based on the temperature information.

[0025] The temperature measuring device 22 is, for example, a thermometer, and any thermometer can be used as long as it can measure the temperature. Also, the information on the measured temperature is transmitted to the determination device 4.

[0026] As will be described later, the stirring device 23 is used to make the concentration of the gas leaked to the outside of the battery B through the seal portion of the battery B uniform inside the sealed container 2 when a reaction occurs inside the battery B and gas is generated due to the supply of the water vapor-containing gas.

[0027] If the gas leaked from the battery B accumulates and the concentration inside the sealed container 2 becomes different, it becomes difficult to accurately measure how much gas has leaked in relation to the detection device 3 described later. Therefore, a stirring device 23 is used to make the concentration of the leaked gas approximately constant inside the sealed container 2.

[0028] As the stirring device 23, for example, it is conceivable to use a fan to make the concentration of the leaked gas inside the sealed container 2 constant. Also, any device other than a fan that can create a gas flow inside the sealed container 2 can be used as the stirring device 23.

[0029] The temperature adjustment device 24 is a device that keeps the temperature inside the sealed container 2 constant during the inspection based on the temperature information measured by the above-described temperature measurement device 22. Note that any method of temperature adjustment may be used.

[0030] The detection device 3 is a device that detects gas leaked from the battery B when performing an airtightness inspection of the battery B. Any method of detecting gas leakage from the battery B may be used. Also, the detection device 3 may be provided with, for example, a mechanism for sucking the gas leaked inside the sealed container 2.

[0031] Also, it may be provided at a position where the leakage location of hydrogen sulfide gas from the battery B can be grasped. That is, for example, the detection device 3 may be provided near all the seal locations of the battery B to be inspected. Also, the water vapor-containing gas supply device 1 and the detection device 3 may be arranged at positions facing each other with the battery B in between.

[0032] The determination device 4 determines the airtightness of the battery B to be inspected based on the gas leaked from the battery B detected by the detection device 3. FIG. 2 is a block diagram showing the internal configuration of the determination device 4 in the airtightness inspection device for the battery B according to the embodiment of the present invention. The determination device 4 includes an information acquisition unit 41, a storage unit 42, a threshold setting unit 43, and a determination unit 44. Further, each unit is connected to the bus B1, and transmission and reception of information are enabled.

[0033] For example, when the water vapor concentration contained in the water vapor-containing gas supplied inside the sealed container 2 is unknown, the information acquisition unit 41 acquires the information on the water vapor concentration transmitted from the water vapor concentration measurement device 21. Also, for example, regarding the temperature inside the sealed container 2, the information acquisition unit 41 acquires the information on the temperature measured by the temperature measurement device 22.

[0034] The storage unit 42 is composed of, for example, a semiconductor storage device, a magnetic storage device, an optical storage device, etc. Alternatively, the storage unit 42 may include memories such as registers, cache memories, ROM (Read Only Memory) and RAM (Random Access Memory) used as a main storage device.

[0035] The storage unit 42 stores, for example, information on the known water vapor concentration in the water vapor-containing gas supplied inside the sealed container 2, a determination program used when the determination unit 44 determines the airtightness of the battery B to be inspected, etc. Also, setting thresholds and expressions used when the threshold setting unit 43 described below sets a determination threshold may be stored.

[0036] The threshold setting unit 43 sets a determination threshold used when the determination unit 44 determines the airtightness of the battery B to be inspected. When the threshold setting unit 43 sets the determination threshold, it is considered that the object of the airtightness inspection in the embodiment of the present invention is an all-solid-state battery including a sulfide-based solid electrolyte.

[0037] That is, the battery to be subjected to the airtightness inspection disclosed in the prior art document is a liquid-type lithium-ion battery. If the airtightness of the liquid-type lithium-ion battery is low, the gas leaking from the battery is the gas generated by the volatilization and decomposition of the electrolyte components.

[0038] Therefore, regardless of whether any substance is supplied from the outside of the battery, if the seal of the battery is not appropriate, the gas generated inside the battery leaks to the outside of the battery. Therefore, when inspecting the airtightness of the battery, for example, a process such as depressurization is necessary, but it is not necessary to supply any substance when allowing gas to leak from the inside of the battery.

[0039] On the other hand, the battery B targeted by the airtightness inspection method in the embodiment of the present invention is an all-solid-state battery including a sulfide-based solid electrolyte as described above. In the case of such an all-solid-state battery, since the electrolyte is a solid electrolyte rather than a liquid electrolyte, gas is not generated by the volatilization and decomposition of the electrolyte.

[0040] Therefore, in the case of an all-solid-state battery including a solid electrolyte, when inspecting the airtightness, a substance is supplied to the battery and reacted with the solid electrolyte to generate gas, and the airtightness is determined by detecting whether the gas leaks to the outside of the battery.

[0041] The all-solid-state battery in the embodiment of the present invention includes a sulfide-based solid electrolyte. Therefore, when water vapor is supplied to the battery, sulfide reacts with water vapor inside the battery to generate hydrogen sulfide gas. Then, the airtightness is determined by detecting whether the generated hydrogen sulfide gas leaks to the outside of the battery B.

[0042] However, when water vapor is supplied to the sulfide-based solid electrolyte, the amount of hydrogen sulfide gas generated varies depending on the water vapor concentration. That is, when the water vapor concentration is high, the amount of hydrogen sulfide gas generated is larger than when the water vapor concentration is low. This will be described with reference to FIG. 3.

[0043] Note that in the airtightness inspection device A for the battery in the embodiment of the present invention as described above, the airtightness is inspected using information regarding the generated hydrogen sulfide gas. As information regarding the hydrogen sulfide gas, for example, the concentration and the amount can be cited.

[0044] However, when determining the airtightness of the battery B, as information regarding the generated hydrogen sulfide gas, either its concentration or its generation amount may be used. Therefore, in the following description, the case where the airtightness is determined using the amount of hydrogen sulfide gas generated will be taken as an example for explanation.

[0045] FIG. 3 is a schematic diagram showing the relationship between the water vapor concentration and the hydrogen sulfide gas leaking from the battery B when a water vapor-containing gas is supplied to the battery B to be inspected. In FIG. 3, two graphs are shown on the left and right. In either graph, the vertical axis indicates the amount of hydrogen sulfide gas generated by supplying the water vapor-containing gas. On the other hand, the horizontal axis is time.

[0046] Also, among the two graphs, the left graph shows the result when the water vapor concentration contained in the supplied water vapor-containing gas is high. On the other hand, the right graph shows the result when the water vapor concentration contained in the supplied water vapor-containing gas is low.

[0047] When determining the airtightness of the battery B in the embodiment of the present invention, the amount of hydrogen sulfide gas generated by supplying the water vapor-containing gas is compared with a determination threshold value for determination. As described above, the higher the water vapor concentration, the greater the amount of hydrogen sulfide gas generated. On the other hand, when the water vapor concentration is low, the amount of hydrogen sulfide gas generated is small.

[0048] This indicates that the amount of hydrogen sulfide gas generated is in a relationship that depends on the water vapor concentration. Therefore, when determining the airtightness of Battery B, if the threshold value is set without considering the water vapor concentration, the airtightness cannot be accurately determined. Regarding this point, explaining based on FIG. 3, the left graph shows the change in the amount of hydrogen sulfide gas leaked from Battery B over time when the water vapor concentration in the water vapor-containing gas supplied to Battery B to be determined is high.

[0049] In the left graph of FIG. 3, two lines are shown indicating how the amount of hydrogen sulfide gas increases over time. Among these two lines, the line closer to the horizontal axis indicates the amount of hydrogen sulfide gas leaked, for example, for Battery O. In the case of Battery O, the amount of hydrogen sulfide gas leaked does not increase much even as time passes.

[0050] On the other hand, among these two lines, the line that does not indicate the amount of hydrogen sulfide gas leaked from Battery O indicates the amount of hydrogen sulfide gas leaked, for example, for Battery P. In the case of Battery P, when comparing the amount of hydrogen sulfide gas at the same elapsed time with that of Battery O, it can be seen that a larger amount of hydrogen sulfide gas has leaked. That is, it can be said that Battery P has lower airtightness than Battery O.

[0051] Also, in the left graph of FIG. 3, a dotted line parallel to the horizontal axis is shown. This indicates a certain amount of leaked hydrogen sulfide gas, and when this amount is grasped as the leakage amount, the airtightness of the battery for which this leakage amount is recognized is determined to be low. Therefore, this dotted line is the determination threshold value when determining the airtightness of Battery B.

[0052] In this graph, since the line indicating the leakage amount of battery P intersects the determination threshold value, it is considered that the leakage amount will further increase in the future. Since the amount of hydrogen sulfide gas leaked from battery P is more than the threshold value, it is determined that the airtightness of battery P is low. On the other hand, since the line indicating the leakage amount of battery O does not exceed the threshold value even when the leakage amount of hydrogen sulfide gas from battery P exceeds the determination threshold value, it is determined that the airtightness of battery O where the leakage amount is recognized is high.

[0053] On the other hand, also in the right graph of FIG. 3 showing the case where the water vapor concentration in the water vapor-containing gas supplied to the battery housed inside the sealed container 2 is low, the increase in the amount of hydrogen sulfide gas over time is shown by two lines. Among the two lines, the line closer to the horizontal axis indicates the amount of hydrogen sulfide gas leaked, for example, for battery Q. In the case of battery Q, the amount of hydrogen sulfide gas leaked does not increase much even as time passes.

[0054] In contrast, among the two lines, the line that is not the line indicating the amount of hydrogen sulfide gas in battery Q indicates the amount of hydrogen sulfide gas leaked, for example, for battery R. In the case of battery R, when comparing the amount of hydrogen sulfide gas at the same elapsed time with the case of battery Q, a state where a larger amount of hydrogen sulfide gas is leaked is shown. That is, it can be said that battery R has lower airtightness than battery Q.

[0055] Also, in the right graph of FIG. 3, a one-dot chain line parallel to the horizontal axis is shown. This indicates a certain amount of leaked hydrogen sulfide gas. When this amount is grasped as the leakage amount, it is determined that the airtightness of the battery where the leakage amount is recognized is low. Therefore, the amount of hydrogen sulfide gas indicated by the one-dot chain line becomes the determination threshold value when determining the airtightness.

[0056] In this graph, since the line indicating the leakage amount of battery R intersects the determination threshold value, it is considered that the leakage amount will further increase in the future. Since the amount of hydrogen sulfide gas leaked from battery R is more than the threshold value, it is determined that the airtightness of battery R is low. On the other hand, since the line indicating the leakage amount of battery Q does not exceed the threshold value even when the leakage amount of hydrogen sulfide gas from battery R exceeds the determination threshold value, it is determined that the airtightness of battery Q with such a recognized leakage amount is high.

[0057] However, as can be seen from the graphs on the left and right, the determination threshold values used when determining that the airtightness is low are different. That is, as shown by the downward arrow in the right graph of FIG. 3, the determination threshold value indicated by the dashed-dotted line in the right graph is set to a state where the amount of leaked hydrogen sulfide gas is less than the determination threshold value indicated by the dotted line in the left graph.

[0058] As described above, this is because the amount of hydrogen sulfide gas generated depends on the high or low water vapor concentration contained in the supplied water vapor-containing gas. That is, when a water vapor-containing gas containing water vapor with different concentrations is supplied to battery B with low airtightness, the amount of hydrogen sulfide gas generated is larger when the water vapor concentration is high than when the water vapor concentration is low. Therefore, the amount of hydrogen sulfide gas leaked from the grasped battery B also increases.

[0059] Therefore, without considering the water vapor concentration contained in the supplied water vapor-containing gas, when the water vapor concentration contained in the water vapor-containing gas supplied into the sealed container 2 is low, for example, if the determination threshold value indicated by the dotted line in the left graph of FIG. 3 is used to determine the airtightness of battery Q and battery R shown in the right graph, there is a possibility that an appropriate determination cannot be made.

[0060] That is, as described above, in the right graph, the airtightness of battery R is lower than that of battery Q. However, when such batteries are the inspection targets and the airtightness is determined using the determination threshold value indicated by the dotted line in the left graph, it may be determined that not only battery Q but also battery R has high airtightness.

[0061] Furthermore, the following situation can also be considered. Here, FIG. 4 is a schematic diagram for explaining setting a threshold value using water vapor concentration when determining airtightness in an embodiment of the present invention. In FIG. 4, three graphs are shown, one at the upper part and two at the lower part. The contents indicated by the vertical axis and the horizontal axis in each graph are the same as those in the graph shown in FIG. 3.

[0062] In the graph shown at the upper part of FIG. 4, the two determination threshold values described with reference to FIG. 3 are shown. That is, the determination threshold value M shown by the broken line on the upper side is the determination threshold value used when the water vapor concentration in the supplied water vapor-containing gas is high. On the other hand, the lower broken line indicates the determination threshold value N used when the water vapor concentration in the supplied water vapor-containing gas is low.

[0063] Also, when a water vapor-containing gas is supplied to the battery to be inspected, three lines are shown indicating a state where the amount of hydrogen sulfide gas increases over time. Among these, the line shown by the dotted line intersects the determination threshold value M shown by the upper broken line, and shows the increase in the amount of hydrogen sulfide gas in the case of the battery P shown on the left side of FIG. 3 so to speak. Therefore, for the battery P in this case, it is determined that the airtightness is low (in the graph shown at the upper part of FIG. 4, it is shown as "water vapor concentration: high, airtightness: low").

[0064] On the other hand, among the three lines, the dashed-dotted line at the position closest to the horizontal axis does not contact either the broken line indicating the determination threshold value M or the broken line indicating the determination threshold value N. Therefore, it can be said that the line shown by the dashed-dotted line shows the increase in the amount of hydrogen sulfide gas in the case of the battery Q shown on the right side of FIG. 3 so to speak. Therefore, for the battery Q in this case, it is determined that the airtightness is high (in the graph shown at the upper part of FIG. 4, it is shown as "water vapor concentration: low, airtightness: high").

[0065] Between the lines indicated by these dotted lines and the lines indicated by the dashed-dotted lines, a line indicated by a solid line is drawn. This solid line does not reach the dashed line indicating the determination threshold M, while it intersects the dashed line indicating the determination threshold N. Therefore, it is unclear whether the battery indicated by the solid line is a battery with a high water vapor concentration and high airtightness in the supplied water vapor-containing gas (not reaching the dashed line indicating the determination threshold M), or a battery with a low water vapor concentration and low airtightness (intersecting the dashed line indicating the determination threshold N).

[0066] In such a case, if only one of the determination thresholds M or the determination threshold N is set, it is impossible to determine whether the airtightness of the battery R whose leakage amount is indicated by the solid line is high or low, and there is a possibility that appropriate determination as described above may not be performed.

[0067] That is, if only the determination threshold M is set, the battery indicating the increase amount of the hydrogen sulfide gas amount of the solid line is determined to be a battery with high airtightness because the leaked hydrogen sulfide gas amount does not reach the determination threshold M. However, as described above, the water vapor-containing gas supplied to the battery indicating the increase amount of the hydrogen sulfide gas amount indicated by the solid line may have a high water vapor concentration or a low water vapor concentration.

[0068] In such a case, if it is a determination result for a battery supplied with a water vapor-containing gas having a high water vapor concentration, there is no problem because it is determined that the airtightness is high. On the other hand, if it is a determination result for a battery supplied with a water vapor-containing gas having a low water vapor concentration, it must be determined that the airtightness is low. Therefore, if only the determination threshold M is set, the latter may be overlooked.

[0069] Conversely, if only the determination threshold N is set, the battery indicating the increase amount of the hydrogen sulfide gas amount of the solid line is determined to be a battery with low airtightness because the leaked hydrogen sulfide gas amount reaches the determination threshold N. However, as described above, the water vapor-containing gas supplied to the battery indicating the increase amount of the hydrogen sulfide gas amount indicated by the solid line may have a high water vapor concentration or a low water vapor concentration.

[0070] In such a case, if it is a determination result for a battery to which a water vapor-containing gas with a low water vapor concentration is supplied, there is no problem from the viewpoint of removing a battery with low airtightness because it is determined that the airtightness is low. On the other hand, if it is a determination result for a battery to which a water vapor-containing gas with a high water vapor concentration is supplied, originally, it must be determined that the airtightness is high. Therefore, when only the determination threshold N is set, there is a possibility that a battery with high airtightness may be removed as in the latter case.

[0071] Therefore, in the airtightness determination process in the embodiment of the present invention, a determination threshold corresponding to the water vapor concentration in the supplied water vapor-containing gas is set and used. By changing the determination threshold according to the water vapor concentration in this way, it is possible to accurately determine the airtightness of the battery showing the increase amount of the hydrogen sulfide gas amount of the solid line as described above.

[0072] Speaking in accordance with the graph of FIG. 4, by setting a plurality of determination thresholds according to the water vapor concentration, it becomes possible to strictly distinguish a battery with high airtightness when the water vapor concentration is high (battery O in the lower left graph) and a battery with low airtightness when the water vapor concentration is low (battery R in the lower right graph).

[0073] As described above, the threshold setting unit 43 sets a determination threshold according to the water vapor concentration contained in the water vapor-containing gas supplied to the battery B to be inspected.

[0074] That is, for example, using a preset water vapor concentration as a setting threshold, the setting threshold is compared with the water vapor concentration contained in the supplied water vapor-containing gas. Then, it is divided into the case where the water vapor concentration is smaller than the setting threshold and the case where the water vapor concentration is equal to or higher than the setting threshold, and determination thresholds to be used in each case are set. By doing so, as described above, it is possible to perform the airtightness determination using an appropriate determination threshold according to the water vapor concentration.

[0075] However, other items to be considered when setting the determination threshold may be provided. That is, in the airtightness inspection method according to the embodiment of the present invention, the battery B to be inspected is an all-solid-state battery including a sulfide-based solid electrolyte. And the airtightness of the battery B is determined based on the value regarding hydrogen sulfide gas generated by the reaction of moisture contained in the water vapor that has leaked outside the battery B with the sulfide. Therefore, it is premised that a chemical reaction between moisture and sulfide occurs. As described above, the higher the temperature, the faster the reaction rate of the chemical reaction.

[0076] Therefore, for example, using the temperature inside the sealed container 2 in which the battery B to be inspected is housed as the above-described set threshold, considering that the reaction rate varies depending on the temperature, a determination threshold corresponding to the water vapor concentration can be further set.

[0077] Furthermore, the set threshold may be set based on the structure of the battery B itself to be inspected. That is, when the battery is manufactured, specifications are set based on various conditions and experimental results. Therefore, the specification information varies for each battery. Therefore, the specification information of the battery B to be inspected can also be used as the set threshold.

[0078] Examples of the specification information that can be adopted as the set threshold include, for example, the electrolyte exposure area of the battery B, the generation rate of hydrogen sulfide gas from the electrolyte when reacting with water vapor, or the permeation coefficient of the packaging material for moisture and hydrogen sulfide gas. The threshold setting unit 43 sets the set threshold based on such specification information, for example.

[0079] Here, the mechanism until hydrogen sulfide gas leaks from the battery B is as follows. First, the water vapor contained in the water vapor-containing gas supplied inside the sealed container 2 enters the inside of the battery B. Next, the water vapor that has entered the inside of the battery B reacts with the sulfide constituting the solid electrolyte to generate hydrogen sulfide gas. And finally, the generated hydrogen sulfide gas leaks from the inside of the battery B to the outside.

[0080] The threshold setting unit 43 obtains the amount of water vapor entering the inside of the battery B from the formula "Permeation amount of the packaging material of H2O (amount of water vapor entering the inside of the battery B)=Permeation coefficient of H2O×time×partial pressure difference...(Formula 1)".

[0081] Here, the "permeation coefficient of H2O" is one of the above-described specifications information and is a value that can change depending on the temperature. That is, as the temperature inside the sealed container 2 in which the battery B is housed increases, the value of the permeation coefficient also increases, and it becomes easier for water vapor to enter the inside of the battery B. Also, the "partial pressure difference" here indicates the water vapor concentration contained in the water vapor-containing gas supplied inside the sealed container 2.

[0082] After that, the threshold setting unit 43 calculates the amount of hydrogen sulfide gas generated when the water vapor entering the inside of the battery B reacts with the solid electrolyte. The generation amount of the hydrogen sulfide gas can be calculated by using the formula "Generation amount of H2S = Exposed surface area of the solid electrolyte×H2S generation coefficient×Permeation amount of the packaging material of H2O...(Formula 2)".

[0083] Among the (Formula 2), the "exposed surface area of the solid electrolyte" and the "H2S generation coefficient" are the specification information. The "permeation amount of the packaging material of H2O" is a value previously calculated by the threshold setting unit 43 using the above-described (Formula 1). Also, the "H2S generation coefficient" is a value that can change depending on the temperature. That is, as the temperature inside the sealed container 2 in which the battery B is housed increases, the value of the permeation coefficient also increases, and the reaction between water vapor and the sulfide constituting the solid electrolyte proceeds further.

[0084] Finally, the threshold setting unit 43 calculates the amount of hydrogen sulfide gas leaking from the packaging material of the battery B using the generation amount of hydrogen sulfide gas (generation amount of H2S) calculated using the above (Formula 2). Specifically, the formula "Permeation amount of H2S (leakage amount of hydrogen sulfide gas)=Permeation coefficient of H2S×time×partial pressure difference...(Formula 3)" is used.

[0085] Here, the "permeability coefficient of H2S" is also a value that can change with temperature. Similar to the "permeability coefficient of H2O", as the temperature increases, the amount of hydrogen sulfide gas leaking from the inside to the outside of battery B increases. Note that the "partial pressure difference" here indicates the concentration of hydrogen sulfide gas contained in the gas leaking from the inside to the outside of battery B.

[0086] The "permeation amount of H2S (leakage amount of hydrogen sulfide gas)" calculated by the threshold setting unit 43 is a value that can be used to determine that the airtightness is low if hydrogen sulfide gas leaks more than this value when determining the airtightness of battery B to be inspected. Therefore, as described with reference to FIG. 4, in order to finally perform an accurate determination according to the water vapor concentration, this value is adopted as the set threshold value when using the specification information.

[0087] Thereafter, a determination threshold value according to the water vapor concentration is selected by the threshold setting unit 43 for performing the final airtightness determination, and is used in the determination unit 44 to determine the airtightness of battery B to be inspected.

[0088] However, the specification information is not limited to these. Also, the specification information can be a single piece, or any combination of multiple pieces of information can be arbitrarily adopted as the set threshold value. Generally, the more specification information is adopted, the higher the determination accuracy of the airtightness.

[0089] The determination unit 44 uses the determination threshold value set by the threshold setting unit 43 to determine the airtightness of battery B to be inspected. The determination unit 44 compares the amount of hydrogen sulfide gas leaked from battery B and detected by the detection device 3 with the determination threshold value to determine the airtightness of the battery B.

[0090] Note that the specification information is information that is originally set in advance as design values for each battery as described above. For example, for specification information such as the permeation amount of the packaging material of H2O (the amount of water vapor entering the inside of battery B), numerical values obtained through experiments or the like may be used as the specification information.

[0091] [Operation] Next, the process flow of determining the airtightness of the battery by the airtightness inspection device A will be described. In the following, first, the process flow of the airtightness determination process will be described. Then, the process flow of setting the determination threshold by the threshold setting unit 43 will be described separately for different cases.

[0092] FIG. 5 is a flowchart showing the process flow of inspecting the airtightness of the battery according to the embodiment of the present invention. In this flowchart, it is assumed that the battery B to be inspected is previously housed inside the sealed container 2.

[0093] First, a water vapor-containing gas is supplied from the water vapor-containing gas supply device 1 into the sealed container 2 (ST1). When the supply of the water vapor-containing gas is started, a reaction starts between the water vapor and the solid electrolyte in the battery B housed inside the sealed container 2. Of course, when the packaging material of the battery B is surely sealed, the supplied water vapor-containing gas does not enter the inside of the battery B. Therefore, no reaction occurs between the water vapor and the solid electrolyte, and no hydrogen sulfide gas is generated. However, here, the description is made on the premise that the reaction between the two starts and hydrogen sulfide gas leaks.

[0094] At the same time, the information acquisition unit 41 receives a signal indicating that the water vapor-containing gas is supplied from the water vapor-containing gas supply device 1 into the sealed container 2. Then, triggered by receiving this signal, the threshold setting unit 43 sets the determination threshold (ST2). The detailed process flow of setting the determination threshold will be described later.

[0095] When the reaction between the water vapor and the solid electrolyte proceeds, the hydrogen sulfide gas generated inside the battery B leaks to the outside (inside the sealed container 2). The amount of the leaked hydrogen sulfide gas is measured by the detection device 3 (ST3).

[0096] The information on the amount of hydrogen sulfide gas measured by the detection device 3 is transmitted to the determination unit 44. Also, the determination threshold value set by the threshold value setting unit 43 is transmitted to the determination unit 44. Therefore, the determination unit 44 compares the amount of hydrogen sulfide gas with the determination threshold value (ST4).

[0097] When the amount of hydrogen sulfide gas is greater than the determination threshold value as a result of the comparison between the amount of hydrogen sulfide gas and the determination threshold value in the determination unit 44 (YES in ST4), it is determined that the airtightness of the battery B under inspection is low (ST5).

[0098] On the other hand, when the determination unit 44 determines that the amount of hydrogen sulfide gas is less than or equal to the determination threshold value as a result of the comparison between the amount of hydrogen sulfide gas and the determination threshold value (NO in ST4), it is determined that the airtightness of the battery B under inspection is high (ST6).

[0099] Next, the case of using only the water vapor concentration when setting the determination threshold value in the threshold value setting unit 43 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the flow of the process of setting the threshold value in the airtightness inspection process of the battery B in the embodiment of the present invention.

[0100] The threshold value setting unit 43 first grasps the water vapor concentration contained in the water vapor-containing gas supplied into the sealed container 2 (ST11). For this water vapor concentration, for example, the information transmitted from the above-described water vapor concentration measuring device 21 is used.

[0101] On the other hand, when the water vapor concentration contained in the supplied water vapor-containing gas is known, for example, it is grasped based on the information on the water vapor concentration contained in the supplied water vapor-containing gas stored in the storage unit 42.

[0102] The threshold value setting unit 43 acquires information on the set threshold value (water vapor concentration) preset as the set threshold value from the storage unit 42. Then, the grasped water vapor concentration is compared with the acquired set threshold value (ST12).

[0103] As a result, when the water vapor concentration is lower than the set threshold value (YES in ST12), the storage unit 42 is accessed, and the determination threshold value (here, the "first determination threshold value") set in association with the set threshold value used for comparison is selected (ST13).

[0104] On the other hand, when the water vapor concentration is equal to or higher than the set threshold value (NO in ST12), the storage unit 42 is accessed, and the determination threshold value (here, the "second determination threshold value") set in association with the set threshold value used for comparison is selected (ST14).

[0105] Note that when the water vapor concentration is equal to or higher than the set threshold value, it means that the water vapor concentration is high. Therefore, the determination threshold value (second determination threshold value) selected here is a larger value than the determination threshold value (first determination threshold value) when the water vapor concentration is lower than the set threshold value.

[0106] In this way, the determination threshold value is set in the threshold value setting unit 43. As described above, in the determination unit 44, the set determination threshold value is used to determine the airtightness of the battery B to be inspected.

[0107] Next, the case where temperature information is used as the set threshold value will be described with reference to FIG. 7. FIG. 7 is a flowchart showing the flow of the process of setting the threshold value in the process of inspecting the airtightness of the battery B in the embodiment of the present invention.

[0108] First, the water vapor concentration contained in the water vapor-containing gas supplied into the sealed container 2 is grasped (ST21). This point is the same as the flow when setting the determination threshold value described with reference to FIG. 6.

[0109] Next, the temperature information inside the sealed container 2 is grasped (ST22). The temperature information is the information measured by the temperature measuring device 22 and transmitted to the determination device 4. The reason for grasping the temperature information is that, as described above, for example, the reaction rate between water vapor and the solid electrolyte increases as the temperature increases.

[0110] Therefore, the threshold setting unit 43 accesses the storage unit 42 to obtain a set threshold value preset in relation to the temperature. Then, the grasped temperature information is compared with the obtained set threshold value (ST23).

[0111] As a result, when the temperature is lower than the set threshold value (YES in ST23), the storage unit 42 is accessed to select the set threshold value used for the comparison and the determination threshold value (here, the "third determination threshold value") set in association with the water vapor concentration (ST24).

[0112] On the other hand, when the temperature is equal to or higher than the set threshold value (NO in ST23), the storage unit 42 is accessed to select the set threshold value used for the comparison and the determination threshold value (here, the "fourth determination threshold value") set in association with the water vapor concentration (ST25).

[0113] Note that when the temperature is equal to or higher than the set threshold value, it means that the temperature inside the sealed container 2 is high. Therefore, the determination threshold value (fourth determination threshold value) selected here is a larger value than the determination threshold value (third determination threshold value) when the temperature is lower than the set threshold value.

[0114] In this way, the determination threshold value is set in the threshold setting unit 43. As described above, the determination unit 44 uses the set determination threshold value to determine the airtightness of the battery B to be inspected.

[0115] Next, the case of using the specification information as the set threshold value will be described with reference to FIG. 8. FIG. 8 is a flowchart showing the flow of the process of setting the threshold value in the airtightness inspection process of the battery B according to the embodiment of the present invention.

[0116] First, the water vapor concentration and temperature included in the water vapor-containing gas supplied into the sealed container 2 are grasped (ST31 and ST32). This point is the same as the flow when setting the determination threshold value described with reference to FIG. 7.

[0117] Next, the specifications information of the battery B to be inspected is grasped (ST33). This is because, for each battery B to be inspected, for example, the permeation amount in the packaging material of the battery B is different.

[0118] Therefore, the threshold setting unit 43 accesses the storage unit 42 to obtain the set threshold value preset in relation to the specifications information. Then, the grasped specifications information and the obtained set threshold value are compared (ST34).

[0119] As a result, when the specifications information is a value lower than the set threshold value (YES in ST34), the storage unit 42 is accessed to select the set threshold value used for the comparison and the determination threshold value (here, the "fifth determination threshold value") set in association with the water vapor concentration (ST35).

[0120] On the other hand, when the specifications information is a value equal to or higher than the set threshold value (NO in ST34), the storage unit 42 is accessed to select the set threshold value used for the comparison and the determination threshold value (here, the "sixth determination threshold value") set in association with the water vapor concentration (ST36).

[0121] Note that the case where the specifications information is a value equal to or higher than the set threshold value is, for example, when the permeation amount of the packaging material in the battery B is larger. Therefore, the determination threshold value (sixth determination threshold value) selected here is a value larger than the determination threshold value (fifth determination threshold value) when the specifications information is smaller than the set threshold value.

[0122] In this way, the determination threshold value is set in the threshold setting unit 43. As described above, the determination unit 44 uses the set determination threshold value to determine the airtightness of the battery B to be inspected.

[0123] Regarding the process of comparing the above-described specifications information with the set threshold value, for the convenience of the above explanation, a plurality of adoptable specifications information as described above has been explained as one piece of specifications information. However, instead of making a determination with the set threshold value in this way, for example, after comparing with the set threshold value set for each individual piece of specifications information, the process may be performed to set the final determination threshold value.

[0124] In addition, in the flowcharts shown in FIGS. 6 to 8, one set threshold value acquired from the storage unit 42 is used to compare with the water vapor concentration, temperature, etc. However, it is also possible to use a plurality of set threshold values. When using a plurality of set threshold values in this way, the number of determination threshold values to be set increases as compared with the case of using one set threshold value. Therefore, it becomes possible to determine the airtightness of the battery B with higher accuracy.

[0125] Note that, so far, “the amount of hydrogen sulfide gas” has been described as an example of information regarding the generated hydrogen sulfide gas. The amount of hydrogen sulfide gas is the total amount of hydrogen sulfide gas generated from the battery B over time.

[0126] However, as described above, it is also possible to determine the airtightness using “the concentration of hydrogen sulfide gas”. Since the concentration of hydrogen sulfide gas is information regarding the hydrogen sulfide gas leaked from the battery B at a certain point in time, when using the concentration of hydrogen sulfide gas, it is possible to immediately determine the airtightness regardless of the passage of time. Therefore, it is possible to shorten the inspection time.

[0127] [Effects of the Embodiment] (1) The method for inspecting the airtightness of a battery according to the embodiment of the present invention includes a step of supplying a water vapor-containing gas into a sealed container in which a battery including a sulfide-based solid electrolyte is housed, a step of setting a determination threshold value based on information on the water vapor concentration contained in the water vapor-containing gas, a step of detecting hydrogen sulfide gas generated from the battery when the water vapor-containing gas is supplied to the battery, a step of comparing a value related to the detected hydrogen sulfide gas with the determination threshold value, and a step of determining the airtightness of the battery based on a result of comparing the value related to the hydrogen sulfide gas with the determination threshold value.

[0128] By adopting such a determination method, it becomes possible to determine the airtightness of the all-solid-state battery by grasping the leakage of hydrogen sulfide gas based on the partial pressure difference of water vapor supplied when inspecting the airtightness of the all-solid-state battery.

[0129] (2) In the above (1), the water vapor concentration contained in the water vapor-containing gas includes both cases where it is known and where it is unknown. When the water vapor concentration is unknown, a step of measuring the water vapor concentration is provided before the step of setting the determination threshold value.

[0130] When determining the airtightness of the battery to be inspected, especially when the water vapor concentration contained in the water vapor-containing gas supplied to the battery is unknown, the water vapor concentration is measured in advance. Thereby, a determination threshold value corresponding to the water vapor concentration can be used.

[0131] (3) In the step of setting the determination threshold value in the above (1) or (2), the determination threshold value is set to a first determination threshold value when the water vapor concentration is lower than the set threshold value, and to a second determination threshold value which is higher than the first determination threshold value when the water vapor concentration is equal to or higher than the set threshold value. In this way, by setting and using a plurality of determination threshold values according to the water vapor concentration, the airtightness of the battery can be determined with higher accuracy.

[0132] (4) In the step of setting the determination threshold value in the above (1) to (3), in addition to the information on the water vapor concentration, the determination threshold value is set using the information on the temperature inside the sealed container. It becomes possible to set a determination threshold value considering the influence of temperature, such as the reaction between water vapor and the solid electrolyte.

[0133] (5) In the step of setting the determination threshold value in the above (4), after dividing into the case where the temperature information is lower than the set threshold value and the case where the temperature information is equal to or higher than the set threshold value, in each case, the determination threshold value is set based on the information on the water vapor concentration.

[0134] The higher the temperature, the faster the reaction between water vapor and the solid electrolyte. By also using the temperature information, the change in the leakage amount of hydrogen sulfide gas accompanying the change in temperature can be grasped, so that the airtightness of the battery can be determined with higher accuracy.

[0135] (6) In the step of setting the determination threshold value in the above (4) or (5), in addition to the temperature information, the determination threshold value is set using the specification information of the battery. The amount and concentration of hydrogen sulfide gas leaked vary depending on the specifications of the battery to be inspected. Therefore, by also considering the specifications of the battery, more accurate determination of airtightness can be performed.

[0136] (7) In the step of setting the determination threshold value in the above (6), after dividing into the case where the specification information is lower than the set threshold value and the case where the specification information is equal to or higher than the set threshold value, in each case, the determination threshold value is set based on the information on the water vapor concentration and the temperature information.

[0137] When setting the determination threshold value, first perform sorting using the set threshold value based on the specifications of the battery to be inspected, and then set the determination threshold value. Therefore, it becomes possible to perform highly accurate determination of airtightness considering the characteristics of each battery to be inspected.

[0138] (8) It includes a sealed container that houses a battery equipped with a sulfide-based solid electrolyte, a water vapor-containing gas supply device that supplies a water vapor-containing gas inside the sealed container, a detection device that detects hydrogen sulfide gas generated from the battery when the water vapor-containing gas is supplied to the battery, and a determination device that sets a determination threshold value based on the information on the water vapor concentration of the water vapor-containing gas supplied inside the sealed container, compares the determination threshold value with the value related to the hydrogen sulfide gas, and determines the airtightness of the battery.

[0139] By inspecting the airtightness of the battery using such a battery airtightness inspection device adopting such a configuration, when inspecting the seal performance (airtightness) in all-solid-state batteries, it becomes possible to grasp the leakage of hydrogen sulfide gas based on the partial pressure difference of water vapor supplied and determine the airtightness of all-solid-state batteries.

[0140] Incidentally, as described above, as devices that can be added to the water vapor-containing gas supply device 1, for example, three devices, namely, a flow rate measurement device 11, a humidity adjustment device 12, and a flow rate adjustment device 13, were cited. Here, if the flow rate measurement device 11 is provided, it is possible to prevent the reaction between the water vapor contained in the supplied water vapor-containing gas and the solid electrolyte from proceeding and the amount of moisture contained in the supplied water vapor-containing gas from becoming insufficient, and an effect of preventing a decrease in water vapor concentration can be expected.

[0141] That is, in the relationship between the "water vapor concentration" and the "flow rate of the water vapor-containing gas", if the flow rate of the water vapor-containing gas is small, the amount of moisture supplied relatively decreases. Therefore, if the reaction between water vapor and the solid electrolyte proceeds inside the battery, the amount of moisture required for the reaction may become insufficient.

[0142] As a result, if the amount of moisture supplied becomes insufficient, there is a possibility that accurate determination cannot be made. Therefore, in order to always keep the water vapor concentration (partial pressure difference) in the supplied water vapor-containing gas constant, a flow rate measurement device 11 may be provided to supply a certain flow rate constantly into the sealed container 2.

[0143] Also, by providing the humidity adjustment device 12, the humidity (water vapor concentration) of the water vapor-containing gas supplied to the inside of the sealed container 2 (inside the battery B) can be increased. If the water vapor concentration increases, the reaction rate with the solid electrolyte will also increase, so the inspection time can be shortened.

[0144] Furthermore, by providing the flow rate adjustment device 13, it is possible to maintain the water vapor concentration of the water vapor-containing gas supplied to the inside of the sealed container 2 (inside the battery B) and prevent the partial pressure difference of the water vapor concentration in the water vapor-containing gas from changing. This can prevent the reaction between water vapor and the solid electrolyte from accelerating or decelerating, and enable a more stable airtightness determination.

[0145] In addition, as described above, as devices that can be added to the sealed container 2, in addition to the water vapor concentration measuring device 21 and the stirring device 23, for example, a temperature measuring device 22 and a temperature adjusting device 24 are mentioned. Among these, the temperature measuring device 22 is used, as described above, for example, to set a determination threshold that can be used as a set threshold to more accurately determine airtightness.

[0146] This is because the reaction rate between water vapor and the solid electrolyte changes depending on the temperature inside the sealed container 2. However, the arrangement position of the temperature measuring device 22 is not particularly limited. Therefore, for example, it is also possible to arrange the temperature measuring device 22 so as to be in contact with the packaging material of the battery B that is the inspection target.

[0147] By arranging the temperature measuring device 22 at such a position, it becomes possible to more finely grasp the influence of temperature on the reaction inside the battery, so that a more accurate determination of airtightness can be performed.

[0148] In addition, by providing the temperature adjusting device 24, it becomes possible to adjust the temperature inside the sealed container 2 (inside the battery B). Therefore, the reaction rate inside the battery B that is the inspection target can be adjusted, and the inspection time can be adjusted.

[0149] Furthermore, in FIG. 1, the arrangement positions of the respective devices constituting the airtightness inspection device A are not particularly specified. However, for example, it is also possible to arrange the water vapor-containing gas supply device 1 above the sealed container 2 and the detection device 3 below the sealed container 2.

[0150] By arranging the water vapor-containing gas supply device 1 and the detection device 3 at the above-described positions with respect to the sealed container 2, the generated hydrogen sulfide gas will move to the lower part of the sealed container 2. Therefore, it is possible to suppress the convection of the hydrogen sulfide gas inside the sealed container 2.

Explanation of Reference Numerals

[0151] 1... Steam-containing gas supply device, 2... Sealed container, 3... Detection device, 4... Judgment device, 11... Flow rate measurement device, 12... Humidity adjustment device, 13... Flow rate adjustment device, 21... Water vapor concentration measurement device, 22... Temperature measurement device, 23... Stirring device, 24... Temperature adjustment device, 41... Information acquisition unit, 42... Memory unit, 43... Threshold setting unit, 44... Judgment unit

Claims

1. A step of supplying a water vapor-containing gas into a sealed container in which a battery including a sulfide-based solid electrolyte is housed; A step of setting a determination threshold based on information on the water vapor concentration contained in the water vapor-containing gas; A step of detecting hydrogen sulfide gas generated from the battery when the water vapor-containing gas is supplied to the battery; A step of comparing a value related to the detected hydrogen sulfide gas with the determination threshold; A step of determining the airtightness of the battery based on a result of comparing the value related to the hydrogen sulfide gas with the determination threshold; A method for inspecting the airtightness of a battery, comprising the above steps.

2. The water vapor concentration contained in the water vapor-containing gas includes both cases where it is known and cases where it is unknown. When the water vapor concentration is unknown, a step of measuring the water vapor concentration is provided before the step of setting the determination threshold. The method for inspecting the airtightness of a battery according to Claim 1, characterized in that.

3. In the step of setting the determination threshold, when the water vapor concentration is lower than a set threshold, the determination threshold is set to a first determination threshold, and when the water vapor concentration is equal to or higher than the set threshold, the determination threshold is set to a second determination threshold which is a value higher than the first determination threshold. The method for inspecting the airtightness of a battery according to Claim 1, characterized in that.

4. In the step of setting the determination threshold, the determination threshold is set using information on the temperature in the sealed container in addition to the information on the water vapor concentration. The method for inspecting the airtightness of a battery according to Claim 1, characterized in that.

5. In the step of setting the determination threshold, after dividing into cases where the temperature information is lower than a set threshold and cases where the temperature information is equal to or higher than the set threshold, in each case, the determination threshold is set based on the information on the water vapor concentration. The method for inspecting the airtightness of a battery according to Claim 4, characterized in that.

6. In the step of setting the determination threshold, the determination threshold is set using the specifications information of the battery in addition to the temperature information. The method for inspecting the airtightness of a battery according to Claim 4, characterized in that.

7. In the step of setting the determination threshold value, after dividing into the case where the specifications information is lower than the set threshold value and the case where the specifications information is equal to or higher than the set threshold value, in each case, the determination threshold value is set based on the information on the water vapor concentration and the information on the temperature. The method for inspecting the airtightness of a battery according to claim 6, characterized in that.

8. A sealed container that houses a battery provided with a sulfide-based solid electrolyte, A water vapor-containing gas supply device that supplies a water vapor-containing gas into the sealed container, A detection device that detects hydrogen sulfide gas generated from the battery when the water vapor-containing gas is supplied to the battery, A determination device that sets a determination threshold value based on information on the water vapor concentration of the water vapor-containing gas supplied into the sealed container, compares the determination threshold value with a value related to the hydrogen sulfide gas, and determines the airtightness of the battery. An airtightness inspection device for a battery, characterized by comprising.

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