Inspection device and inspection method for battery module

Abstract

The present invention provides an inspection method for a battery module, the method being capable of identifying not only the presence or absence of a failure in a block constituting the battery module, but also identifying the type of the failure. This inspection method is for a battery module that includes at least one block in which single batteries of a plurality of secondary batteries are connected in series and / or in parallel, the method including: a step 1 for discharging the single batteries of the plurality of secondary batteries included in the block; a step 2 for repeatedly recording the voltage of the block during step 1 for a first prescribed time period for each unit time period; and a step 3 for determining whether the block corresponds to any of a plurality of predetermined failure modes on the basis of the change over time of the voltage of the block as obtained by step 2.

Description

Battery module inspection method and inspection apparatus

[0001] This invention relates to a method and apparatus for inspecting battery modules. In particular, this invention relates to a method and apparatus for inspecting battery modules of sodium-sulfur batteries.

[0002] Compared to conventional generators, storage batteries can change output power at a much faster rate, making them effective for regulating the frequency of the power grid, adjusting the difference between the power generated by renewable energy generators and the planned output power, and adjusting the power demand and supply of the power grid.

[0003] One example of a high-temperature operating battery connected to a power grid is a sodium-sulfur battery (hereinafter also referred to as "NAS battery"). An NAS battery has a configuration in which a bottomed cylindrical component made of a solid electrolyte such as β-alumina is placed inside a metal container on the positive electrode side, which serves as the housing case. Sodium is contained as the negative electrode active material on the inside of the bottomed cylindrical component, and sulfur is contained as the positive electrode active material on the outside. In an NAS battery, during discharge, ionized sodium permeates through the solid electrolyte and reacts with sulfur to produce sodium polysulfide, generating electricity. Conversely, the reverse reaction produces sodium and sulfur, which is used for charging.

[0004] NAS batteries are typically provided as battery modules, housing multiple single cells connected in series and / or parallel within a box. For example, a battery module has a structure in which circuits (strings) of multiple single cells connected in series are connected in parallel to form blocks, and at least two of these blocks are connected in series. Furthermore, it is also possible to provide a large-scale containerized battery by connecting multiple battery modules to each other and housing them together with control equipment in a container.

[0005] Conventionally, a method for inspecting battery modules is known in which abnormalities are detected and reported by comparing the discharge depth of each block constituting the battery module (Patent Document 1). Furthermore, in order to quickly identify the module that is the source of the abnormality when an abnormality occurs, a method is known in which the abnormal module is identified based on the difference between a reference block voltage obtained from the correlation between the block voltage value and the average block voltage value and the block voltage value (Patent Document 2).

[0006] Japanese Patent Publication No. 3-158781, International Publication No. 2015 / 029832

[0007] Thus, conventional battery module inspection methods can detect modules or blocks where abnormalities (hereinafter referred to as "failures") have occurred. However, even when such failures are detected, the cause of the failure is not singular, but rather can vary. Therefore, if information about the type of failure that occurred can be obtained, it would be easier to identify the cause of the failure and enable the necessary repairs to the battery module to be carried out quickly.

[0008] In view of the above circumstances, the object of the present invention is to provide, in one embodiment, a method for inspecting a battery module that can identify not only whether or not there is a fault in the blocks constituting the battery module, but also the type of fault.

[0009] The inventors of the present invention diligently studied to solve the above problems and found that failures in the blocks constituting a battery module are not random but can be classified into several types, and that this can be determined by monitoring the voltage of each block. The present invention was completed based on this finding and is illustrated below. [Aspect 1] A method for inspecting a battery module comprising at least one block in which multiple secondary battery cells are connected in series and / or parallel, comprising: step 1 of discharging the multiple secondary battery cells included in the block; step 2 of repeatedly recording the voltage of the block during step 1 for a first predetermined time at unit time intervals; and step 3 of determining whether the block falls into any of a predetermined failure mode based on the change in the voltage of the block obtained in step 2 over time. [Aspect 2] The inspection method according to aspect 1, wherein the first predetermined time is 14 hours or less. [Aspect 3] The inspection method according to aspect 1 or 2, wherein the unit time is 1 second to 5 minutes. [Aspect 4] An inspection method according to any one of aspects 1 to 3, wherein in step 3, the voltage difference D1 of the block that occurred in the first determination interval during the first predetermined time is compared with a predetermined normal voltage difference D2 in the first determination interval, and it is determined that the block corresponds to one of the plurality of failure modes if the relationship between the two satisfies predetermined conditions. [Aspect 5] An inspection method according to aspect 4, wherein the first determination interval is 5 minutes or more. [Aspect 6] An inspection method according to any one of aspects 1 to 5, wherein in step 3, it is determined that the block corresponds to one of the plurality of failure modes if the voltage difference d1 of the block for each unit time during the first predetermined time satisfies predetermined conditions. [Aspect 7] An inspection method according to aspect 6, which includes specifying the time at which d1 satisfying the predetermined conditions is detected. [Aspect 8] An inspection method according to any one of aspects 1 to 7, wherein in step 3, the voltage difference of the block per unit time calculated based on the voltage of the block recorded from the first to the Nth time (where N is an integer between 2 and 30) in the first predetermined time satisfies a predetermined condition, and it is determined that the block corresponds to one of the plurality of failure modes.[Aspect 9] An inspection method according to any one of aspects 1 to 8, comprising: step 4, which charges the individual cells of the plurality of secondary batteries contained in the block following a waiting period after step 1; step 5, which repeatedly records the voltage of the block during step 4 for a second predetermined time at each unit time interval; and step 6, which determines whether the block falls under any of the plurality of failure modes based on the change in the voltage of the block obtained in step 5 over time. [Aspect 10] An inspection method according to aspect 9, wherein the second predetermined time interval is 14 hours or less. [Aspect 11] An inspection method according to aspect 9 or 10, wherein in step 6, it is determined that the value d2 of the difference in the voltage of the block at each unit time interval during the second predetermined time interval satisfies a predetermined condition, thereby determining whether the block falls under one of the plurality of failure modes. [Aspect 12] An inspection method according to any one of aspects 1 to 11, wherein each of the plurality of secondary batteries is a sodium-sulfur battery. [Aspect 13] A battery module inspection device for performing the inspection method according to any one of aspects 1 to 12, comprising: a block voltage measurement unit capable of repeatedly measuring the voltage of the block for a predetermined time at unit intervals; a storage device capable of recording the voltage of the block measured by the block voltage measurement unit in association with the time at which the voltage was measured; and a determination unit capable of determining whether the block falls under one of a predetermined number of failure modes based on the change in the voltage of the block over time. [Aspect 14] A battery module inspection device according to aspect 13, further comprising an output unit capable of notifying the type of failure mode when the determination unit determines that the block falls under one of the multiple failure modes.

[0010] According to one embodiment of the present invention, it is possible to provide a battery module inspection method that can identify not only whether or not there are faults in the blocks constituting the battery module, but also the type of fault. This inspection method can be used, for example, for pre-shipment inspections as well as for fault monitoring when the battery module is in operation in the field. By being able to identify the type of fault, it becomes easier to identify the cause of the fault, and it is thought that necessary repairs to the battery module can be carried out quickly.

[0011] This is a schematic cross-sectional view illustrating the internal structure of a module battery according to one embodiment of the present invention. This is a schematic electrical circuit diagram of a plurality of single cells included in a module battery according to one embodiment of the present invention. This is a schematic partial cross-sectional view showing the vicinity of the positive electrode of a module battery according to one embodiment of the present invention. This is a schematic partial cross-sectional view showing the vicinity of the negative electrode of a module battery according to one embodiment of the present invention. This is an example of a functional block diagram of a battery module inspection device according to one embodiment of the invention. This is an example of the change in voltage of the block over time during discharge to illustrate failure mode A. This is an example of the change in voltage of the block over time during discharge to illustrate failure mode B. This is an example of the change in voltage of the block over time during discharge to illustrate failure mode C. This is an example of the change in voltage of the block over time during discharge to illustrate failure mode D. This is an example of the change in voltage of the block over time during discharge to illustrate failure mode H. This is a schematic longitudinal cross-sectional view showing an example of the overall structure of a single cell of a sodium-sulfur battery (NAS battery).

[0012] Next, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and it should be understood that appropriate design changes, improvements, etc., can be made based on the ordinary knowledge of those skilled in the art, without departing from the spirit of the invention.

[0013] (1. Overall configuration of the battery module) The battery module 10 according to one embodiment of the present invention has a substantially rectangular shape when viewed from above, and as shown in Figure 1, it has, for example, a box-shaped container 14 and a lid 16 that closes the upper opening of the container 14. The container 14 and the lid 16 can be designed to be vacuum insulated. The container 14 houses a battery collection 20 composed of a plurality of individual secondary batteries 18 connected in series and / or in parallel.

[0014] Each cell 18 is cylindrical or otherwise columnar in shape and is housed in the container 14 with its axial direction parallel to the vertical. Each cell 18 has a negative terminal 18a and a positive terminal 18b at one end in the axial direction. To address damage to the cell 18, abnormal overheating, or leakage of active material, silica sand is filled in the gaps between the container 14 and the multiple cell 18 as fire extinguishing sand (not shown). Examples of secondary batteries include sodium-sulfur batteries, lithium-ion batteries, and sodium-ion batteries. In one embodiment, all of the multiple secondary battery cell 18s are sodium-sulfur batteries. As sodium-sulfur batteries, those capable of generating a voltage of approximately 1.8 to 2.3V can be used.

[0015] Figure 7 schematically shows a longitudinal cross-sectional view illustrating an example of the overall structure of a single cell of a sodium-sulfur battery (NAS battery) 110. In one embodiment, the sodium-sulfur battery 110 comprises a positive electrode side body portion 121, a positive electrode side bottom cover 124 joined to the lower end of the positive electrode side body portion 121, a positive electrode ring fitting 122 joined to the upper end of the positive electrode side body portion 121, a positive electrode terminal 123 joined to the upper end of the positive electrode ring fitting 122, a negative electrode ring fitting 131 arranged on the inner circumference of the positive electrode ring fitting 122 and electrically insulated from the positive electrode ring fitting 122 by an insulating ring 140, and a negative electrode side top cover 132 joined to the upper end of the negative electrode ring fitting 131. A negative electrode terminal 139 is provided on the upper surface of the negative electrode side top cover 132. The negative electrode side top cover 132 and the negative electrode terminal 139 can be provided, for example, as an integrally molded product.

[0016] The NAS battery (single cell) is housed in a sheath tube 180. A heat insulating and / or insulating cover 182 is wrapped around and fixed to the outer circumference of the sheath tube 180. Examples of the cover 182 include mica sheets and fire-resistant carbon sheets. Since mica sheets have both heat insulating and insulating properties, they can be used for either application, and flexible mica of MT66 as specified in JIS C2255:1992 can be suitably used. For example, a heat insulating mica sheet, a fire-resistant carbon sheet, and an insulating mica sheet can be wrapped around the sheath tube 180 in this order from the inner circumference to the outer circumference to form the cover 182. In addition, a heat insulating and / or insulating plate material 184 is also adhered and fixed to the bottom surface of the sheath tube 180. An insulating mica plate is an example of the plate material 184.

[0017] The positive electrode body portion 121, positive electrode bottom cover 124, positive electrode ring fitting 122, positive electrode terminal 123, negative electrode ring fitting 131, and negative electrode top cover 132 can be made of a metal such as aluminum or an aluminum alloy. For example, aluminum alloy A3003 as specified in JIS H4000:2014 is preferably used. Furthermore, welding, particularly electron beam welding, can be preferably used to join metal parts such as the joint between the positive electrode body portion 121 and the positive electrode bottom cover 124, the joint between the positive electrode body portion 121 and the positive electrode ring fitting 122, the joint between the positive electrode ring fitting 122 and the positive electrode terminal 123, and the joint between the negative electrode ring fitting 131 and the negative electrode top cover 132.

[0018] Aluminum oxide such as α-alumina is preferably used as the material for the insulating ring 140. The insulating ring 140 is joined to the outer circumference of the upper end of a bottomed cylindrical (typically bottomed cylindrical) solid electrolyte 150. Beta-alumina and / or beta''-alumina are preferably used as the material for the solid electrolyte 150. The insulating ring 140 and the solid electrolyte 150 can be joined by glass.

[0019] Inside the bottomed cylindrical solid electrolyte 150 is a bottomed cylindrical (typically bottomed cylindrical) negative electrode container 136 that houses sodium 130 as a negative electrode active material. A small hole 136a is provided at the bottom of the negative electrode container 136. The negative electrode container 136 can be made of high-chromium steel, stainless steel (SUS304, etc.), aluminum alloy, SPCC (cold-rolled steel sheet), etc. Outside the negative electrode container 136, inside the solid electrolyte 150, is a bottomed cylindrical safety tube 170. The safety tube 170 can be made of aluminum or an aluminum alloy. Exemplarily, an A3003 aluminum alloy as specified in JIS H4000:2014 can be suitably used. The gap between the solid electrolyte 150 and the safety tube 170 (the gap in the radial direction (horizontal direction in the figure)) is preferably 30 to 100 μm, and more preferably 50 to 80 μm. A particle size of 30 μm or more is preferable because it allows for the movement of sodium 130 without significantly increasing pressure loss. A particle size of 100 μm or less is preferable for safety reasons.

[0020] Furthermore, sulfur 120, which serves as the positive electrode active material, is contained within a space (positive electrode space) 128 surrounded by the positive electrode body portion 121 and the positive electrode bottom cover 124 on the outside of the bottomed cylindrical solid electrolyte 150. Since sulfur 120 is an insulator, it is common to arrange a positive electrode current collector 127 to ensure conductivity between the positive and negative electrodes and to reduce the internal resistance of the battery. The positive electrode current collector 127 can be made of a felt material consisting of conductive carbon fibers and / or graphite fibers, and by impregnating it with the sulfur 120 positive electrode active material and arranging it so as to contact both the inner circumferential surface of the positive electrode body portion 121 and the outer circumferential surface of the bottomed cylindrical solid electrolyte 150, conductivity between the positive and negative electrodes is ensured and the internal resistance of the battery is reduced.

[0021] The space 137 inside the negative electrode container 136 is filled with an inert gas such as argon, helium, or neon as a pressure (negative electrode side pressure) source. The positive electrode space 128 is filled with nitrogen gas as a pressure (positive electrode side pressure) source.

[0022] During discharge, the pressure of the inert gas causes the molten sodium 130 in the negative electrode container 136 to be supplied to the safety tube 170 through the small hole 136a. The supplied sodium 130 fills the safety tube 170, and any overflowing sodium 130 is supplied to the space (negative electrode space) 138 between the solid electrolyte 150 and the safety tube 170. Of the sodium 130 supplied between the solid electrolyte 150 and the safety tube 170, those that have released electrons to the external circuit through the negative electrode terminal 139 in the negative electrode space 138 and become sodium ions pass through the solid electrolyte 150 into the positive electrode space 128, where they react with the sulfur 120 and electrons supplied from the external circuit through the positive electrode terminal 123 to produce sodium polysulfide. This allows for the generation of a voltage of, for example, 1.8 to 2.3 V.

[0023] During charging, when a voltage is applied from an external circuit through the positive electrode terminal 123 and the negative electrode terminal 139, sodium polysulfide releases electrons to the external circuit through the positive electrode terminal 123, generating sulfur and sodium ions. The generated sodium ions then permeate (pass through) the solid electrolyte 150 and move into the negative electrode space 138. The sodium ions that have moved into the negative electrode space 138 move inward, overcoming the upper end of the safety tube 170, and move into the negative electrode container 136 through the small hole 136a. There, they react with electrons supplied from the external circuit through the negative electrode terminal 139, becoming electrically neutralized (becoming sodium 130), thereby converting electrical energy into chemical energy.

[0024] The positive electrode side body portion 121 may have a constriction 121a. The constriction 121a provides a spring effect to the positive electrode side body portion 121, which can mitigate expansion and contraction of the positive electrode side body portion 121 due to thermal changes. After the positive electrode solidifies, the portion where the positive electrode current collector 127 is located is fixed in place by sulfur or sodium polysulfide and does not move, so it is preferable that the constriction 121a is located above the position where the positive electrode current collector 127 is housed.

[0025] The container 14 has a shape that is close to a rectangular parallelepiped, and has four side walls and one bottom wall, and an upper opening. The container 14 is made of a plate material made of metal such as stainless steel, and has a hollow section 22 inside the side walls and bottom wall. The hollow section 22 is an airtight sealed space, and is structured so that the hollow section 22 can communicate with the outside space by a vacuum valve (not shown). The hollow section 22 can be filled with a porous heat insulating board 24 made of glass fibers solidified into a plate shape with adhesive, making the container 14 a vacuum heat insulating structure.

[0026] In addition to the aforementioned battery assemblies 20, the container 14 is also equipped with, although not shown, multiple heaters for maintaining a predetermined temperature inside the container 14, multiple thermometers for measuring the temperature inside the container 14, and multiple voltage measurement lines for measuring block voltage, etc.

[0027] The lid 16 is equipped with a top wall 26 and a canopy 28, and is installed to close the upper opening of the container 14. It has a hollow section 30 inside the top wall 26 and canopy 28. Like the container 14, the lid 16 is made of a metal plate material such as stainless steel. The hollow section 30 is an airtight sealed space, and is structured so that the hollow section 30 can communicate with the outside space by a vacuum valve (not shown). It is possible to make the lid 16 a vacuum-insulated structure by loading a porous insulation board 32, which is made of glass fibers solidified into a plate shape with adhesive, into the hollow section 30.

[0028] On the other hand, the battery assemblies 20 comprises at least one block. The battery assemblies 20 may be constructed by connecting two or more blocks 38 in series from the positive electrode 34 to the negative electrode 36, as shown in Figure 2. Each block 38 may have multiple single secondary battery cells 18 connected in series and / or in parallel. In one embodiment, each block 38 can be constructed by connecting two or more circuits (strings 40) in which two or more single cells 18 are connected in series in parallel.

[0029] In one embodiment, the battery module 10 may have 1 to 10 blocks 38, typically 2 to 4 blocks 38. In one embodiment, each block 38 may have 1 to 8 strings 40, typically 1 to 2 strings 40. In one embodiment, each string 40 may have 1 to 32 single cells 18 connected in series, typically 4 to 8 single cells 18 connected in series.

[0030] The positive electrode 34 comprises a positive electrode busbar 42 that constitutes the external connection terminal on the positive electrode side and a positive electrode bus 44 that is an intermediate member, and the positive electrode bus 44 comprises a positive electrode current collector 46 and a positive electrode pole 50. The negative electrode 36 comprises a negative electrode busbar 52 that constitutes the external connection terminal on the negative electrode side and a negative electrode bus 54 that is an intermediate member, and the negative electrode bus 54 comprises a negative electrode current collector 56 and a negative electrode pole 60. The current-carrying parts of the positive electrode 34 and the negative electrode 36 can be made of conductive materials such as metals such as aluminum and aluminum alloys.

[0031] Next, specific configuration examples of the positive electrode 34 and the negative electrode 36 will be described with reference to Figures 3 and 4. As shown in Figure 3, the positive electrode current collector 46 of the positive electrode 34 is housed in the housing space of the container 14. The positive electrode pole 50 penetrates the second side wall 14b of the container 14. The positive electrode current collector 46 follows the inner surface of the second side wall 14b, and the positive electrode pole 50 is coupled to the positive electrode current collector 46 in the housing space of the container 14 and to the positive electrode busbar 42 outside the container 14.

[0032] Furthermore, as shown in Figure 4, the negative electrode current collector 56 is housed in the containment space of the container 14. The negative electrode pole 60 penetrates the third side wall 14c, which is opposite the second side wall 14b, with the first side wall 14a in between. The negative electrode current collector 56 is along the inner surface of the third side wall 14c, and the negative electrode pole 60 is coupled to the negative electrode current collector 56 in the containment space of the container 14 and to the negative electrode busbar 52 outside the container 14.

[0033] Furthermore, configuring the aforementioned positive electrode current collector 46 and negative electrode current collector 56 with metal plates contributes to reducing the electrical resistance of the positive electrode bus 44 and the negative electrode bus 54. Of course, the positive electrode current collector 46 and the negative electrode current collector 56 may each be an assembly of two or more conductive components. Additionally, configuring the positive electrode terminal 50 and the negative electrode terminal 60 each to have a pole shape contributes to suppressing the inflow and outflow of heat via the positive electrode terminal 50 and the negative electrode terminal 60.

[0034] (2. Battery Module Inspection Apparatus) FIG. 5 shows an example of a functional block diagram of an inspection apparatus 70 for a battery module 10 according to an embodiment of the present invention. The inspection apparatus 70 includes a block voltage measurement unit 71, a controller 72, a storage device 73, an output device 74, and an input device 75. The inspection apparatus 70 may inspect one or more blocks 38 in a single battery module 10, or may inspect one or more blocks 38 in a plurality of battery modules 10. For example, the inspection apparatus 70 can inspect 2 to 100 blocks 38 at the same time.

[0035] The controller 72 includes a measurement control unit 72a, a determination unit 72b, an output unit 72c, and an information storage unit 72d. These functions of the controller 72 can be realized by a control and arithmetic device such as a central processing unit (CPU), for example.

[0036] The measurement control unit 72a can control the block voltage measurement unit 71, and can determine the timing of starting and ending an inspection. The start and end of the inspection may be performed manually via the input device 75. The inspection apparatus 70 is configured to be capable of receiving information such as the operating state (during discharging, during charging, in standby) of each block of the battery module 10 from the control device 11 of the battery module 10 via wired or wireless communication. Therefore, the measurement control unit 72a may be configured such that the timing for starting and stopping the block voltage measurement unit 71 is automatically determined in accordance with the operating state of each block of the battery module 10. Alternatively, the measurement control unit 72a may keep the block voltage measurement unit 71 in constant operation regardless of the operating state of each block of the battery module 10.

[0037] The block voltage measuring unit 71 can repeatedly measure the voltage of each corresponding block 38 (block A1, block A2, ...) every unit time for a predetermined period of time in accordance with an instruction from the measurement control unit 72a. Typically, the closed circuit voltage (CCV) is measured during charge and discharge, and the open circuit voltage (OCV) is measured during standby. More specifically, the block voltage measuring unit 71 can repeatedly measure the voltage across both ends of each corresponding block 38 every preset unit time for a predetermined period of time. The function of the block voltage measuring unit 71 can be realized by, for example, a voltmeter. The block voltage measuring unit 71 and the controller 72 may be connected via a wired or wireless connection.

[0038] Conditions to be preset in advance that are required for inspection, such as measurement conditions by the block voltage measuring unit 71 and definitions of a plurality of failure modes, can be input via the input device 75. As the input device 75, one or more of a keyboard, a touch panel, buttons, a microphone, and the like can be used.

[0039] The measured voltage value measured by the block voltage measuring unit 71 is transmitted to the information storage unit 72d via wired or wireless connection. Upon receiving the measured voltage value, the information storage unit 72d associates the measured value with the time point when the voltage was measured and records the same in the storage device 73. The storage device 73 and the controller 72 may be connected via a wired or wireless connection.

[0040] The function of the storage device 73 can be realized by using known storage devices, including primary storage devices mainly using semiconductor memory, secondary storage devices (auxiliary storage devices) mainly using hard disk drives or semiconductor disks, offline storage mainly using removable media drives such as CD-ROM drives, and tape libraries.

[0041] In addition to various inspection data such as the measured voltage values measured by the block voltage measuring unit 71, the storage device 73 may also store an operating system (OS), network applications, programs for executing various types of control and calculation performed by the controller 72, and the like.

[0042] The determination unit 72b can determine whether each block 38 corresponds to one of a predetermined set of failure modes based on the time-dependent change in the voltage of each block 38 recorded in the storage device 73. The inspection device 70 may be configured so that the determination result from the determination unit 72b is stored in the information storage unit 72d.

[0043] In one embodiment, the output unit 72c can notify (output) the determination result to the output device 74. For example, if the determination unit 72b determines that block 38 falls under one or more of a plurality of failure modes, the output unit 72c can notify (output) the type of failure mode to the output device 74. Also, if the determination unit 72b determines that block 38 does not fall under any of the failure modes, i.e., is normal, the output unit 72c can notify (output) the output device 74 of this fact. The output device 74 can be implemented by one or more types of devices such as a monitor, printer, indicator light, and speaker. The output device 74 and the controller 72 may be connected by wire or wireless.

[0044] Once a failure mode is identified, several causes for that failure mode are possible. Therefore, the inspection device 70 may be configured such that the storage device 73 stores a list of causes associated with the type of failure mode, and the output unit 72c notifies the output device 74 of this list along with the type of failure mode.

[0045] The functions of the inspection device 70 may be located in one place, or they may be distributed across multiple locations. For example, the block voltage measurement unit 71 may be installed in the room where the battery module 10 to be inspected is located, while the computer that implements the functions of the controller 72, storage device 73, and output device 74 may be installed in a room separate from the inspection room (e.g., a control room where the production management system for battery modules in the factory is installed).

[0046] (3. Method for inspecting battery modules) The battery module inspection device 70 described above is suitably usable for inspecting battery modules 10 that include at least one block 38 in which multiple single cells 18 of secondary batteries are connected in series and / or parallel. Failure modes can be identified during discharge and charging, and according to this inspection method, multiple failure modes can be identified overall.

[0047] (3-1. Failure Mode Inspection During Discharge) A method for inspecting a battery module 10 according to one embodiment of the present invention includes: step 1, discharging the individual cells 18 of a plurality of secondary batteries included in block 38; step 2, repeatedly recording the voltage of block 38 at first predetermined intervals during step 1; and step 3, determining whether block 38 falls under any of a predetermined set of failure modes based on the change in the voltage of block 38 over time obtained in step 2.

[0048] <Step 1> In Step 1, the individual cells 18 of the multiple secondary batteries contained in block 38 are discharged. If the battery module 10 has multiple blocks 38, some or all of them may be discharged simultaneously. Discharge may be carried out in two or more stages, but it is preferable to discharge each block 38 until its depth of discharge reaches 67% or more, more preferably until it reaches 85% or more, and even more preferably until it reaches 93% or more. In Step 1, the discharge may be carried out until the depth of discharge reaches 100%.

[0049] <Step 2> In Step 2, the voltage of block 38 during Step 1 is repeatedly recorded for a first predetermined time at unit time intervals. The first predetermined time is not particularly limited as long as it is the time necessary to identify the failure mode during discharge, but a longer first predetermined time is preferable for improving inspection accuracy. For this reason, the first predetermined time is preferably 5 minutes or more, more preferably 30 minutes or more, and even more preferably 1 hour or more. On the other hand, a shorter inspection time is more efficient. For this reason, the first predetermined time is preferably 14 hours or less, more preferably 10 hours or less, and even more preferably 3 hours or less. Accordingly, the first predetermined time is preferably, for example, 5 minutes or more and 14 hours or less, more preferably 30 minutes or more and 10 hours or less, and even more preferably 1 hour or more and 3 hours or less. Alternatively, the entire time during which the discharge in Step 1 is performed may be considered the first predetermined time.

[0050] While there are no particular restrictions on the unit time as long as it is the time necessary to identify the failure mode, a shorter unit time is desirable for improving inspection accuracy. From this perspective, a unit time of 5 minutes or less is preferable, 2 minutes or less is more preferable, and 1 minute or less is even more preferable. On the other hand, if the unit time is too short, the amount of data increases while the inspection accuracy saturates. Therefore, a unit time of 1 second or more is preferable, 10 seconds or more is more preferable, and 30 seconds or more is even more preferable. Accordingly, for example, a unit time of 1 second or more and 5 minutes or less is preferable, 10 seconds or more and 2 minutes or less is more preferable, and 30 seconds or more and 1 minute or less is even more preferable.

[0051] The operation of the inspection device 70 when Step 2 is performed using the inspection device 70 described above will now be explained. Before the start of discharge of the battery module 10, simultaneously with the start of discharge, or at a predetermined timing after the start of discharge, the block voltage measurement unit 71 starts measuring the voltage of the corresponding block 38 of the battery module 10, in accordance with the instructions of the measurement control unit 72a of the inspection device 70. The measurement for identifying the failure mode during discharge is repeated for a first predetermined time at unit time intervals, and the voltage of the block 38 measured by the block voltage measurement unit 71 is recorded in the storage device 73 of the inspection device 70 in association with the time when the voltage was measured. In addition, if there are multiple blocks 38 whose voltage is to be measured, an identifier is assigned to each block 38, and the voltage of the block 38 is recorded in the storage device 73 in association with the identifier of the block 38. Based on the information recorded in the storage device 73, the determination unit 72b can make a determination based on the change in the voltage of the measured block 38 over time.

[0052] <Step 3> Failures in the block 38 constituting the battery module 10 during discharge can be classified into several types. Therefore, in step 3, based on the change in the voltage of the block 38 over time obtained in step 2, it is determined whether or not the block 38 falls into one of the predetermined failure modes.

[0053] The operation of the inspection device 70 when step 3 is performed using the inspection device 70 described above will now be explained. The storage device 73 of the inspection device 70 records the time-dependent change of the ideal voltage in the healthy block 38 during discharge in step 2. The time-dependent change of the ideal voltage can be determined, for example, based on statistical data based on past measurement results. The determination unit 72b uses this time-dependent change of ideal voltage as a control standard and determines whether it falls into one of a predetermined number of failure modes based on how the time-dependent change of the voltage of block 38 obtained in step 2 deviates from the control standard. If the determination unit 72b determines that a predetermined block 38 falls into one of the multiple failure modes, the output unit 72c notifies the output device 74 of the determination result, such as the type of failure mode and an identifier that identifies the failed block 38, and the determination result is output through the output device 74. Examples of failure modes that can be identified during discharge are, but are not limited to, the following.

[0054] (Failure Mode A) Failure Mode A is a failure mode in which the rate of voltage decrease is faster or slower than the control standard. Figure 6-1 schematically shows an example of the change over time of the voltage of block 38 during discharge (also called "block voltage") to explain failure Mode A. The difference in voltage of block 38 that occurred in the first determination interval (from t1 to t2) in the first predetermined time is D1 (=V 11 -V 12 ) is the normal difference D2 (=V) of a predetermined voltage in the first determination interval. 21 -V 22 By comparing the two, if the relationship between them satisfies predetermined conditions, it is determined that the block 38 corresponds to one of several failure modes (referred to here as "failure mode A").

[0055] In one embodiment, if the determination value A = |D1 - D2| is greater than a predetermined value, it can be determined that the block 38 is in failure mode A. The predetermined value can be determined, for example, based on statistical data based on past measurements.

[0056] A start time t1 and an end time t2 of the first determination interval may be set in advance. As described above, since the voltage of the block 38 to be inspected is repeatedly recorded (logged) for a first predetermined time every unit time, for example, at a certain logging time t A , the difference (differential value) between the voltage value measured at the next logging time t B measured voltage value satisfies a predetermined condition (e.g., greater than a predetermined value m), it can be considered that there is a start point of voltage drop (or rise). In this case, for example, t A or t B may be set as the start time t1, or t A a logging time point about 1 to 10 times before may be set as the start time t1.

[0057] Alternatively, when the voltage value of the block 38 continuously drops or rises below a normal value (management standard) for a predetermined number of times (e.g., 2 to 5 times), it can also be considered that there is a start point of voltage drop (or rise). In this case, for example, the time point when the predetermined number of times is reached may be set as the start time t1, or a logging time point about 1 to 10 times before the time point when the predetermined number of times is reached may be set as the start time t1.

[0058] The end time t2 can be the same as the discharge end time (when discharging is performed in two or more stages, it refers to the discharge end time of each stage), but is not limited thereto, and a time point when an appropriate time for determining failure mode A has elapsed can be set as the end time t2. For example, the first determination interval (from t1 to t2) is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. The upper limit of the first determination interval is not particularly limited other than depending on the capacity of the battery module 10, but in the case of a NAS battery, it is generally 14 hours or less, and typically 13 hours or less.

[0059] When discharging is performed in two or more stages, the determination of failure mode A may be performed in each discharge stage.

[0060] Possible causes of failure mode A include, for example, the internal components of the single cell (solid electrolyte 150 (β tube) and safety tube 170) being in close contact with each other, reducing the contact area between sodium and the solid electrolyte 150 (β tube), or gas being generated on the solid electrolyte 150 (β tube) due to moisture adsorption, reducing the current-carrying area.

[0061] (Failure Mode B) Failure Mode B is a failure mode in which the voltage drops sharply compared to the control standard. Figure 6-2 schematically shows an example of the change in block voltage over time during discharge to explain Failure Mode B. If the voltage difference d1 of block 38 per unit time during the first predetermined time in Step 1 satisfies a predetermined condition, it is determined that block 38 corresponds to one of several failure modes (here referred to as "Failure Mode B").

[0062] In one embodiment, a predetermined condition regarding d1 is set, for example, that at least one of the voltage differences (derivative values) d1 of block 38 per unit time, calculated from a large number of voltage values ​​recorded over a first predetermined time period, is greater than a predetermined value. If this condition is met, it can be determined that block 38 is in failure mode B. The predetermined condition regarding d1 can be determined based on statistical data based on past measurement results.

[0063] It is preferable to identify the point in time when d1 that satisfies predetermined conditions is detected. When using the inspection device 70, it is preferable that the identified point in time, along with the type of failure mode, is output from the output device 74.

[0064] If the discharge is performed in two or more stages, the failure mode B should be determined at each discharge stage.

[0065] Possible causes of failure mode B include, for example, a drop in internal pressure at the top of the negative electrode, which cuts off the supply of sodium, or a rise in the internal temperature of the module battery causing the safety pipe 170 to become blocked.

[0066] (Failure Mode C) Failure Mode C is a failure mode in which the voltage drop in the initial stage of discharge is larger than that of the control standard. Figure 6-3 schematically shows an example of the change in block voltage over time during discharge to explain Failure Mode C. In a first predetermined time, if the voltage difference of block 38 per unit time calculated based on the voltage of block 38 recorded during logging from the first to the Nth time (N is an integer between 2 and 35, preferably an integer between 10 and 34, more preferably an integer between 25 and 30) satisfies predetermined conditions, it is determined that block 38 corresponds to one of the above-mentioned failure modes (here referred to as "Failure Mode C").

[0067] For example, based on the voltage of block 38 recorded from the first to the fifth time, the voltage difference (derivative value) is calculated between the first and second time, the second and third time, the third and fourth time, and the fourth and fifth time. If the statistical value representing these voltage differences (e.g., the average value) is greater than a predetermined value, it can be determined that block 38 is in failure mode C. The predetermined conditions regarding the voltage drop in the initial stage of discharge can be determined based on statistical data from past measurements.

[0068] If the discharge is performed in two or more stages, the failure mode C should be determined at each discharge stage.

[0069] Possible causes of failure mode C include, for example, thermal expansion of an internal component (insulating ring 140 (α-ring)) causing the glass portion to break, or damage to the glass portion joining the solid electrolyte 150 (β-tube) and the insulating ring 140 (α-ring), resulting in the battery path being blocked. Alternatively, damage to the solid electrolyte 150 (β-tube) itself may have interrupted the ion transfer reaction between sodium and sulfur.

[0070] (3-2. Failure Mode Inspection During Charging) Failure modes can be identified not only during discharge but also during charging. Accordingly, a method for inspecting a battery module 10 according to one embodiment of the present invention includes: step 4, which charges the individual cells 18 of the multiple secondary batteries included in block 38 after a waiting period following step 1; step 5, which repeatedly records the voltage of block 38 at second predetermined unit time intervals during step 4; and step 6, which determines whether the block falls under any of the multiple failure modes based on the change in the voltage of the block obtained in step 5 over time.

[0071] <Step 4> In Step 4, following the waiting period after Step 1, the individual cells 18 of the multiple secondary batteries included in Block 38 are charged. Charging is preferably carried out until the capacity of the individual cells 18 reaches 65% or more, more preferably until it reaches 85% or more, and even more preferably until it reaches 93% or more. In Step 4, charging may be carried out until the capacity of the individual cells 18 reaches 100%.

[0072] The waiting time after Step 1 is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more, in order to calculate the depth of discharge of the module battery from the OCV. There is no particular upper limit set for the waiting time after Step 1, but if the waiting time is prolonged, the overall inspection time will be longer. For this reason, the waiting time after Step 1 is preferably 240 minutes or less, more preferably 180 minutes or less, and even more preferably 120 minutes or less. Thus, the waiting time after Step 1 is preferably, for example, 1 minute or more and 240 minutes or less, more preferably 10 minutes or more and 180 minutes or less, and even more preferably 30 minutes or more and 120 minutes or less.

[0073] <Step 5> In Step 5, the voltage of block 38 during Step 4 is repeatedly recorded for a second predetermined time at unit time intervals. The second predetermined time is not particularly limited as long as it is the time necessary to identify the failure mode during charging, but a longer second predetermined time is preferable for improving inspection accuracy. For this reason, the second predetermined time is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. On the other hand, a shorter inspection time is more efficient. For this reason, the second predetermined time can be 14 hours or less, preferably 11 hours or less, more preferably 8 hours or less, and even more preferably 6 hours or less. Accordingly, the second predetermined time is preferably, for example, 1 minute or more and 11 hours or less, more preferably 10 minutes or more and 8 hours or less, and even more preferably 30 minutes or more and 6 hours or less. Alternatively, the entire time spent charging in Step 4 may be considered the second predetermined time.

[0074] The operation of the inspection device 70 when step 5 is performed using the inspection device 70 described above will now be explained. Before charging of the battery module 10 begins, simultaneously with the start of charging, or at a predetermined timing after the start of charging, the block voltage measurement unit 71 starts measuring the voltage of the corresponding block 38 of the battery module 10, in accordance with the instructions of the measurement control unit 72a of the inspection device 70. Voltage measurement may be performed continuously over the discharge time, standby time, and charging time. Voltage measurement for identifying the failure mode during charging is repeated for a second predetermined time at each unit time, and the voltage of the block 38 measured by the block voltage measurement unit 71 is recorded in the storage device 73 of the inspection device 70 in association with the time when the voltage was measured. In addition, if there are multiple blocks 38 whose voltage is to be measured, an identifier is assigned to each block 38, and the voltage of the block 38 is recorded in the storage device 73 in association with the identifier of the block 38. Based on the information recorded in the storage device 73, the determination unit 72b can make a determination based on the change in the voltage of the measured block 38 over time.

[0075] <Step 6> In Step 6, based on the change in the voltage of block 38 over time obtained in Step 5, it is determined whether block 38 falls into one of a predetermined set of failure modes.

[0076] The operation of the inspection device 70 when step 6 is performed using the inspection device 70 described above will now be explained. The storage device 73 of the inspection device 70 records the time-dependent change of the ideal voltage in a healthy block 38 during charging in step 6. The time-dependent change of the ideal voltage can be determined, for example, based on statistical data based on past measurements. The determination unit 72b uses this time-dependent change of ideal voltage as a control standard and determines whether it falls into one of a predetermined number of failure modes based on how the time-dependent change of the voltage of block 38 obtained in step 5 deviates from the control standard. If the determination unit 72b determines that a predetermined block 38 falls into one of the multiple failure modes, the output unit 72c notifies the output device 74 of the determination result, such as the type of failure mode and an identifier that identifies the faulty block 38, and the determination result is output through the output device 74. Examples of failure modes that can be identified during charging, though not limited to these, are as follows.

[0077] (Failure Mode D) Failure Mode D is a failure mode in which the voltage rises or falls sharply compared to the control standard. Figure 6-4 schematically shows an example of the change in block voltage over time during charging to explain Failure Mode D. During the second predetermined time in Step 4, if the voltage difference d2 of block 38 per unit time satisfies predetermined conditions, it is determined that block 38 corresponds to one of several failure modes (here referred to as "Failure Mode D").

[0078] In one embodiment, a predetermined condition regarding d2 is set, for example, that at least one of the voltage differences (derivative values) d2 of block 38 per unit time, calculated from a large number of voltage values ​​recorded over a second predetermined time period, is greater than a predetermined value. If this condition is met, it can be determined that block 38 is in failure mode D. The predetermined condition regarding d2 can be determined based on statistical data based on past measurement results.

[0079] It is preferable to identify the point in time when d2 that satisfies predetermined conditions is detected. When using the inspection device 70, it is preferable that the identified point in time, along with the type of failure mode, is output from the output device 74.

[0080] If charging is performed in two or more stages, a failure mode D check should be performed at each charging stage.

[0081] One possible cause of failure mode D is that the internal component (safety tube 170) expands due to the temperature rise after discharge, causing damage to the solid electrolyte 150 (β tube).

[0082] (Failure Mode E) Failure Mode E is a failure mode in which the rate of voltage rise is faster or slower than the control standard, and is similar to Failure Mode A, although there is a difference between discharge and charge. The voltage difference D1 (=V) of block 38 that occurred in the second determination interval (from t1 to t2) in the second predetermined time is 11 -V 12 ) is the predetermined normal voltage difference D2 (=V) in the second determination interval. 21 -V 22 By comparing the two, if the relationship between them satisfies predetermined conditions, it is determined that block 38 corresponds to one of several failure modes (referred to here as "failure mode E").

[0083] In one embodiment, if the determination value E = |D1 - D2| is greater than a predetermined value, it can be determined that the block 38 is in failure mode E. The predetermined value can be determined, for example, based on statistical data based on past measurements.

[0084] The start time t1 and end time t2 of the second judgment interval can be set in advance. As mentioned above, the voltage of the block 38 being inspected is repeatedly recorded (logged) for a second predetermined time at each unit time, so for example, at a certain logging time t A The voltage value measured and the next logging time t B When the difference (derivative value) of the measured voltage values ​​satisfies a predetermined condition (e.g., greater than a predetermined value m), it can be considered that there was a point where the voltage decrease (or increase) began. In this case, for example, t A or t B The starting point t1 may be used, or t A The starting point t1 may be defined as a logging point that occurred 1 to 10 times earlier than the current point.

[0085] Alternatively, the voltage drop (or rise) can be considered to have started when the voltage value of block 38 drops or rises below the normal value (control standard) for a predetermined number of consecutive times (e.g., 2 to 5 times). In this case, for example, the start time t1 may be the time when the predetermined number of times is reached, or it may be the start time t1 may be the logging point about 1 to 10 times before the time when the predetermined number of times is reached.

[0086] The termination time t2 can be the same as the end of charging (or the end of each stage of charging if charging is performed in two or more stages), but is not limited to this, and can be the time when an appropriate amount of time has elapsed to determine the failure mode E. For example, the second determination interval (from t1 to t2) is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 30 minutes or longer. The upper limit of the second determination interval is not particularly limited except that it depends on the capacity of the battery module 10, but in the case of a NAS battery, it is generally 14 hours or less, and typically 13 hours or less.

[0087] If charging is performed in two or more stages, a failure mode E check should be performed at each charging stage.

[0088] One possible cause of failure mode E is that the internal component (safety tube 170) expands due to the temperature rise after discharge, causing damage to the solid electrolyte 150 (β tube).

[0089] (3-3. Failure Mode Inspection During Standby) Failure modes can be identified not only during discharge and charging, but also during the standby time after step 1 until step 4 is started. Accordingly, a method for inspecting a battery module 10 according to one embodiment of the present invention includes: step 7, which repeatedly records the voltage of block 38 during standby after step 1 for a third predetermined time at unit time intervals; and step 8, which determines whether the block falls under any of a plurality of failure modes based on the change in the voltage of the block obtained in step 7 over time.

[0090] <Step 7> In Step 7, the voltage of block 38 during the standby period after Step 1 is repeatedly recorded for a third predetermined time at unit time intervals. The third predetermined time is not particularly limited as long as it is the time necessary to identify the failure mode during standby, but a longer third predetermined time is preferable for improving inspection accuracy. For this reason, the third predetermined time is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more. On the other hand, a shorter inspection time is more efficient. For this reason, the third predetermined time is preferably 240 minutes or less, more preferably 180 minutes or less, and even more preferably 120 minutes or less. Accordingly, the third predetermined time is preferably, for example, 1 minute or more and 240 minutes or less, more preferably 10 minutes or more and 180 minutes or less, and even more preferably 30 minutes or more and 120 minutes or less. Alternatively, the entire standby time may be the third predetermined time.

[0091] The operation of the inspection device 70 when step 7 is performed using the inspection device 70 described above will now be explained. Simultaneously with the start of standby of the battery module 10, or at a predetermined timing after the start of standby, the block voltage measurement unit 71 starts measuring the voltage of the corresponding block 38 of the battery module 10, in accordance with the instructions of the measurement control unit 72a of the inspection device 70. Voltage measurement may be performed continuously over the discharge time and standby time. Voltage measurement for identifying the failure mode during standby is repeated for a third predetermined time at each unit time, and the voltage of the block 38 measured by the block voltage measurement unit 71 is recorded in the storage device 73 of the inspection device 70 in association with the time when the voltage was measured. In addition, if there are multiple blocks 38 whose voltage is to be measured, an identifier is assigned to each block 38, and the voltage of the block 38 is recorded in the storage device 73 in association with the identifier of the block 38. Based on the information recorded in the storage device 73, the determination unit 72b can make a determination based on the change in the voltage of the measured block 38 over time.

[0092] <Step 8> In Step 8, based on the change in the voltage of block 38 obtained in Step 7, it is determined whether block 38 falls into one of a predetermined set of failure modes.

[0093] The operation of the inspection device 70 when step 8 is performed using the inspection device 70 described above will now be explained. The storage device 73 of the inspection device 70 records the time-dependent change of the ideal voltage in the healthy block 38 during standby in step 6. The time-dependent change of the ideal voltage can be determined, for example, based on statistical data based on past measurement results. The determination unit 72b uses this time-dependent change of ideal voltage as a control standard and determines whether it falls into one of a predetermined number of failure modes based on how the time-dependent change of the voltage of block 38 obtained in step 7 deviates from the control standard. If the determination unit 72b determines that a predetermined block 38 falls into one of the multiple failure modes, the output unit 72c notifies the output device 74 of the determination result, such as the type of failure mode and an identifier that identifies the failed block 38, and the determination result is output through the output device 74. Examples of failure modes that can be identified during charging are, but are not limited to, the following.

[0094] <Failure Mode F> The standby voltage represents the battery's discharge depth. As the discharge depth progresses, the standby voltage decreases. When a single cell 18 fails, power cannot be supplied to that location, and the discharge depth of the other usable single cells 18 progresses = the voltage decreases. Failure Mode F can be identified by utilizing this characteristic. Failure Mode F can be identified in the same way as Failure Mode B described above. That is, if the amount of voltage drop d3 of block 38 per unit time during the third predetermined time in step 7 satisfies a predetermined condition, it is determined that block 38 corresponds to one of several failure modes (here referred to as "Failure Mode F").

[0095] In one embodiment, a predetermined condition regarding d3 is set, for example, that at least one of the voltage drop amounts (derivative values) d3 of block 38 per unit time, calculated from data of numerous voltage values ​​recorded over a third predetermined time period, is greater than a predetermined value. If this condition is met, it can be determined that block 38 corresponds to failure mode F. The predetermined condition regarding d3 can be determined based on statistical data based on past measurement results. After a voltage change corresponding to failure mode F is recorded, the voltage difference may continue as is during standby, or the voltage may recover and return to normal during standby. Therefore, it is also possible to determine whether failure mode F is classified into one of these two categories and record the determination result.

[0096] It is preferable to identify the point in time when d3 that satisfies predetermined conditions is detected. When using the inspection device 70, it is preferable that the identified point in time, along with the type of failure mode, is output from the output device 74.

[0097] <Failure Mode G> Failure Mode G is a failure mode in which a sharp voltage increase is observed during standby. Failure Mode G can be identified in the same way as failure Mode D described above. That is, if the amount of voltage increase d4 of block 38 per unit time during the third predetermined time in step 7 satisfies predetermined conditions, it is determined that block 38 corresponds to one of the multiple failure modes (here referred to as "failure mode G").

[0098] In one embodiment, a predetermined condition regarding d4 is set to, for example, that at least one of the voltage increase (derivative value) d4 of block 38 per unit time, calculated from data of a large number of voltage values ​​recorded over a third predetermined time period, is greater than a predetermined value. If this condition is met, it can be determined that block 38 corresponds to failure mode G. The predetermined condition regarding d4 can be determined based on statistical data based on past measurement results. After a voltage change corresponding to failure mode G is recorded, the voltage difference may continue as is during standby, or the voltage may return to normal during standby. For this reason, it is also possible to determine whether failure mode G is classified into one of these two categories and record the determination result.

[0099] It is preferable to identify the point in time when d4 that satisfies predetermined conditions is detected. When using the inspection device 70, it is preferable that the identified point in time, along with the type of failure mode, is output from the output device 74.

[0100] <Failure Mode H> Failure Mode H is a failure mode caused by a voltage drop during standby, similar to Failure Mode F. However, Failure Mode H is determined when the area S of the region enclosed by the voltage profile of block 38 at a third predetermined time during step 7 and a predetermined normal voltage profile at the third predetermined time satisfies predetermined conditions, and block 38 is determined to be one of several failure modes (here referred to as "Failure Mode H"). For example, if the area S is greater than a predetermined value, it can be determined that block 38 is in Failure Mode H (see Figure 6-5).

[0101] In one embodiment, predetermined conditions regarding the area S can be determined based on statistical data derived from past measurements.

[0102] The various failure modes described above can each be determined independently. Therefore, for example, a device may exhibit failure mode A and also fall under failure mode B. However, some failure modes, such as failure mode A and failure mode C, are incompatible.

[0103] 10: Battery module 11: Control device 14: Container 14a: First side wall 14b: Second side wall 14c: Third side wall 16: Cover 18: Single cell 18a: Negative terminal 18b: Positive terminal 20: Battery assembly 22: Hollow section 24: Insulation board 26: Top wall 28: Canopy 30: Hollow section 32: Insulation board 34: Positive electrode 36: Negative electrode 38: Block 40: String 42: Positive electrode busbar 44: Positive electrode bus 46: Positive electrode current collector 50: Positive electrode pole 52: Negative electrode busbar 54: Negative electrode bus 56: Negative electrode current collector 60: Negative electrode pole 70: Inspection device 71 : Block voltage measurement unit 72 : Controller 72a : Measurement control unit 72b : Judgment unit 72c : Output unit 72d : Information storage unit 73 : Storage device 74 : Output device 75 : Input device 110 : Sulfur battery 120 : Sulfur 121 : Positive electrode side body 122 : Positive electrode ring fitting 123 : Positive electrode terminal 124 : Positive electrode side bottom cover 127 : Positive electrode current collector 128 : Positive electrode space 130 : Sodium 131 : Negative electrode ring fitting 132 : Negative electrode side top cover 136 : Negative electrode container 136a : Small hole 137 : Space 138 : Negative electrode space 139 : Negative electrode terminal 140 : Insulating ring 150 : Solid electrolyte 170 : Safety tube 180 : Sheath tube 182: Covering body 184: Plate material

Claims

A method for testing a battery module comprising at least one block in which multiple rechargeable batteries are connected in series and / or in parallel, Step 1 involves discharging the individual cells of the plurality of secondary batteries included in the block, Step 2 involves repeatedly recording the voltage of the block during step 1 for a first predetermined time at unit time intervals, Step 3 involves determining whether the block falls into one of a predetermined set of failure modes based on the change in the voltage of the block over time obtained in Step 2. A method for inspecting battery modules, including [specific components / features]. 　 The inspection method according to claim 1, wherein the first predetermined time is 14 hours or less. 　 The inspection method according to claim 1, wherein the unit time is 1 second to 5 minutes. 　 The inspection method according to claim 1, wherein in step 3, the voltage difference D1 of the block that occurred in the first determination interval during the first predetermined time is compared with a predetermined normal voltage difference D2 in the first determination interval, and if the relationship between the two satisfies predetermined conditions, it is determined that the block corresponds to one of the plurality of failure modes. 　 The inspection method according to claim 4, wherein the first determination interval is 5 minutes or longer. 　 The inspection method according to claim 1, wherein in step 3, the difference d1 of the voltage of the block per unit time in the first predetermined time satisfies a predetermined condition, and it is determined that the block corresponds to one of the plurality of failure modes. 　 The inspection method according to claim 6, which includes identifying the point in time when d1 that satisfies the predetermined conditions is detected. 　 The inspection method according to claim 1, wherein in step 3, it is determined that the block corresponds to one of the plurality of failure modes if the voltage difference of the block per unit time, calculated based on the voltage of the block recorded from the first to the Nth time (where N is an integer between 2 and 30) in the first predetermined time, satisfies a predetermined condition. 　 Step 4 involves charging the individual cells of the multiple secondary batteries included in the block, following the waiting period after step 1. Step 5 involves repeatedly recording the voltage of the block during step 4 for a second predetermined time at each unit time interval, Step 6 involves determining whether the block falls under any of the multiple failure modes based on the change in voltage of the block over time obtained in step 5, The inspection method according to claim 1, including the following: 　 The inspection method according to claim 9, wherein the second predetermined time is 14 hours or less. 　 The inspection method according to claim 9, wherein in step 6, it is determined that the value d2 of the voltage difference of the block per unit time in the second predetermined time satisfies a predetermined condition, and that it corresponds to one of the plurality of failure modes. 　 The inspection method according to claim 1, wherein each of the multiple secondary batteries is a sodium-sulfur cell. 　 A block voltage measurement unit capable of repeatedly measuring the voltage of the block at predetermined intervals for a predetermined time, A storage device capable of recording the voltage of the block measured by the block voltage measurement unit, associated with the time when the voltage was measured, A determination unit capable of determining whether the block falls into one of a predetermined set of failure modes based on the change in the voltage of the block over time, An inspection apparatus for a battery module for carrying out the inspection method according to any one of claims 1 to 12, comprising: 　 The battery module inspection device according to claim 13, further comprising an output unit capable of notifying the type of failure mode when the determination unit determines that the block corresponds to one of the plurality of failure modes.

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