Short-circuit inspection method and short-circuit inspection device

Abstract

By performing individual short-circuit tests to determine whether each cell is good or bad before stacking, it becomes possible to reduce the defect rate and improve the yield of the stacked battery. [Solution] The method comprises the steps of: placing a single cell C, on one surface 51a of the current collector 51, a first positive electrode active material layer 52, a first solid electrolyte layer 53, and a first negative electrode active material layer 54 are stacked in this order, and on the other surface 51b of the current collector 51, a second positive electrode active material layer 55, a second solid electrolyte layer 56, and a second negative electrode active material layer 57 are stacked in this order, on the receiving part 1 such that either the first negative electrode active material layer 54 or the second negative electrode active material layer 57 is in contact with the single cell C; and having the measuring part 3 contact the single cell C to measure the voltage of the single cell C, wherein the measured voltage of the single cell C is the voltage between the first negative electrode active material layer 54 and the current collector 51, and the voltage between the second negative electrode active material layer 57 and the current collector 51.

Description

Technical Field

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[0001] Embodiments of the present invention relate to a short - circuit inspection method and a short - circuit inspection device.

Background Art

[0002] Patent Document 1 discloses an inspection method for a battery that can effectively detect electrical short - circuit defects in a battery configured by sealing an electrode laminate in which a positive electrode, a separator, and a negative electrode are laminated with a pair of laminate films.

[0003] The inspection method in Patent Document 1 is said to perform the inspection in two steps. That is, first, as the first withstand - voltage determination step, with the electrode laminate accommodated in the laminate film and no electrolyte injected, a first voltage is applied between the positive - electrode terminal and the negative - electrode terminal to perform a withstand - voltage determination. Next, as the second withstand - voltage determination step, a second voltage higher than the first voltage is applied between the positive - electrode terminal or the negative - electrode terminal and the metal layer to perform a withstand - voltage determination.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the inspection method disclosed in Patent Document 1 is a method of promoting insulation breakdown in the cell and measuring the insulation resistance at this time to determine whether there is a short - circuit. And the object of this inspection is a battery configured by sealing an electrode laminate in which a positive electrode, a separator, and a negative electrode are laminated with a pair of laminate films. When a short - circuit is detected, the entire battery is determined to be a defective product.

[0006] However, although the battery consists of multiple electrode layers, it is unclear which electrode layer caused the short circuit due to dielectric breakdown. Therefore, even if there are electrode layers that do not experience dielectric breakdown and are judged to be good products, if dielectric breakdown occurs in other electrode layers, the entire battery will be treated as defective. Consequently, the defect rate tends to be higher compared to, for example, inspecting each electrode layer individually, resulting in a worse yield.

[0007] Furthermore, even though it is for inspection purposes, applying a high voltage to the battery during manufacturing accelerates dielectric breakdown, so even if the battery as a whole is judged to be good quality, the dielectric breakdown of the battery is accelerated. Therefore, it cannot be said with certainty that there is no possibility of short circuits or other problems occurring during operation when such batteries are shipped and installed in vehicles. Even if such problems do not occur, the fact remains that the battery is subjected to stress during inspection, which could ultimately shorten its lifespan.

[0008] The present invention was made to solve the above problems, and the object of the present invention is to provide a short-circuit inspection method and a short-circuit inspection device that can reduce the defect rate and improve the yield of batteries after stacking single cells by performing a quality determination by short-circuit inspection on each individual cell before stacking. [Means for solving the problem]

[0009] The short-circuit inspection method in an embodiment of the present invention comprises the steps of: placing a single cell, on a receiving portion such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with the cell, the single cell having a first positive electrode active material layer, a first solid electrolyte layer, and a first negative electrode active material layer laminated in that order on one side of the current collector, and a second positive electrode active material layer, a second solid electrolyte layer, and a second negative electrode active material layer laminated in that order on the other side of the current collector; and having a measuring portion contact the single cell to measure the voltage of the single cell, wherein the measured voltage of the single cell is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector.

[0010] Furthermore, the short-circuit inspection device in the embodiment of the present invention comprises a receiving portion in which a single cell is arranged such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with the first negative electrode active material layer, the receiving portion fixes the single cell placed in the receiving portion at a position opposite the receiving portion with the single cell in between, a measuring portion that contacts the fixed single cell to measure the voltage of the single cell, and a voltage measuring device that determines the quality of the single cell using the voltage of the single cell measured by the measuring portion, wherein the voltage of the single cell measured by the measuring portion is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector. [Effects of the Invention]

[0011] By employing such a short-circuit inspection method and short-circuit inspection device, the present invention provides a short-circuit inspection method and short-circuit inspection device that can reduce the defect rate and improve the yield of batteries after stacking individual cells by performing a pass / fail judgment by short-circuit inspection on each individual cell before stacking.

[0012] Furthermore, by employing the short-circuit inspection method and short-circuit inspection device according to the embodiment of the present invention, high voltage is not applied when inspecting a single cell, thus enabling pass / fail determination based on short-circuit inspection without promoting dielectric breakdown. [Brief explanation of the drawing]

[0013] [Figure 1] This is an overall view of the short-circuit testing device according to an embodiment of the present invention, shown from the front with a single cell placed on it. [Figure 2] Figure 2(A) is a front view and Figure 2(B) is a top view of the short-circuit testing device according to an embodiment of the present invention. [Figure 3] This is a block diagram showing the internal configuration of the voltage measuring device of a short-circuit inspection device according to an embodiment of the present invention. [Figure 4] This is a plan view showing the position where the measuring probe of the measuring unit of the short-circuit inspection device in an embodiment of the present invention contacts a single cell. [Figure 5] This is a plan view showing another position where the measuring probe of the measuring unit of the short-circuit inspection device in an embodiment of the present invention contacts a single cell. [Figure 6] This is a flowchart showing the inspection flow in a short-circuit inspection device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the drawings are schematic and may differ from actual ones. Furthermore, the embodiments of the present invention shown below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the structure, arrangement, etc., of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0015] FIG. 1 is an overall view showing the entire short-circuit inspection device S according to an embodiment of the present invention, as viewed from the front with a single cell C placed thereon. The short-circuit inspection device S in the embodiment of the present invention is a device used to inspect whether a single cell C is short-circuited.

[0016] Therefore, first, the structure of the single cell C will be described using FIG. 2. FIG. 2 is an overall view of the single cell C to be inspected in the short-circuit inspection device S according to an embodiment of the present invention, where FIG. 2(A) is a front view and FIG. 2(B) is a plan view.

[0017] As shown in FIG. 2(A), the direction in which each substance described later is laminated is defined as the Z direction, the direction orthogonal to the Z direction and horizontal in the drawing is defined as the X direction. Also, the direction orthogonal to both the Z direction and the X direction is defined as the Y direction. Note that these directions are the same not only in FIG. 2 but also in other drawings.

[0018] As shown in FIG. 2(A), the single cell C has, around the current collector 51, on one surface 51a of the current collector 51, a first positive electrode active material layer 52, a first solid electrolyte layer 53, and a first negative electrode active material layer 54 laminated in this order. And on the other surface 51b of the current collector, a second positive electrode active material layer 55, a second solid electrolyte layer 56, and a second negative electrode active material layer 57 are laminated in this order.

[0019] FIG. 2(B) is a plan view showing the single cell C as described above so that one surface 51a of the current collector 51 can be seen. Here, in the single cell C, each substance is shown in a rectangular shape. The first negative electrode active material layer 54 is at the most central part, the first solid electrolyte layer 53 can be seen under it, and further, one surface 51a of the current collector 51 can be seen under that. Since the first positive electrode active material layer 52 is approximately the same size as the solid electrolyte layer 53, it cannot be seen hidden by the first solid electrolyte layer 53 in the plan view of FIG. 2(B).

[0020] The single cell C shown in FIG. 2 is a so-called all-solid-state battery. For example, a solid electrolyte is used as the electrolyte, and lithium metal or a lithium-containing alloy is used as the negative electrode. As shown in FIG. 2(A), the single cell C is generally flat in shape. A plurality of such single cells C are stacked in the thickness direction to form a single battery cell. Further, a plurality of such battery cells are stacked to form a battery module.

[0021] Incidentally, as described above, the positive electrode active material layer laminated on one surface 51a of the current collector 51 is represented as the first positive electrode active material layer 52, the solid electrolyte layer is represented as the first solid electrolyte layer 53, and the negative electrode active material layer is represented as the first negative electrode active material layer 54. Also, each material laminated on the other surface 51b of the current collector 51 is represented as the second positive electrode active material layer 55, the second solid electrolyte layer 56, and the second negative electrode active material layer 57, respectively.

[0022] However, this way of representation is only for the sake of convenience to distinguish the respective positive electrode active material layers, solid electrolyte layers, and negative electrode active material layers laminated on both surfaces of the current collector 51. Therefore, for example, the positive electrode active material layer, solid electrolyte layer, and negative electrode active material layer laminated on one surface 51a of the current collector 51 may be represented as the second positive electrode active material layer 55, the second solid electrolyte layer 56, and the second negative electrode active material layer 57, respectively.

[0023] Returning to FIG. 1, the short-circuit inspection device S includes a receiving portion 1, a pressing portion 2, a measuring portion 3, and a voltage measuring device 4. The single cell C to be inspected is placed on the receiving portion 1 during the inspection.

[0024] Since the single cell C is configured in the shape as described above, the negative electrode active material layer is placed in contact with the receiving portion 1. In FIG. 1, the second negative electrode active material layer 57 is placed in contact with the receiving portion 1. However, the first negative electrode active material layer 54 may be placed in contact with the receiving portion 1.

[0025] As described above, the single cell C to be inspected is placed on the receiving unit 1. During inspection, the measuring unit 3, which will be described later, will make contact with multiple points on the single cell C. Therefore, if the single cell C is simply placed on the receiving unit 1, it is possible that the single cell C may move due to contact with the measuring unit 3.

[0026] Therefore, the receiving portion 1 in the short-circuit inspection device S in the embodiment of the present invention may be provided with, for example, a mechanism for fixing the placed single cell C. However, when fixing the single cell C, it is not possible to damage the single cell C by fixing it with a hard member such as a fixing device.

[0027] Therefore, although not shown in Figure 1, the receiving portion 1 may have, for example, numerous air holes formed in the receiving portion 1 that penetrate through the receiving portion 1 in the Z direction, and a method can be adopted in which the single cell C is attracted to and fixed to the receiving portion 1 by drawing in air through these air holes.

[0028] Since the current collector 51 is formed to be very thin, when the single cell C is fixed by drawing in air, the outer edge of the current collector 51 is pulled downward in the Z direction, as shown in Figure 1, and is attracted to the surface of the receiving part 1, for example.

[0029] Furthermore, if it is possible to place and secure the single cell C on the receiving part 1 without damaging it, a method other than the air suction method described above for securing it can also be used.

[0030] Furthermore, an opening 11 is formed on the lower side of the receiving portion 1 in the Z direction, so that the measuring portion 3 can come into contact with the second negative electrode active material layer 57, as will be described later. The size of the opening 11 does not need to be large enough to allow the measuring portion 3 to come into contact with the second negative electrode active material layer 57. The shape of the opening is also not particularly limited.

[0031] The short-circuit inspection device S in the embodiment of the present invention further includes a holding portion 2. The holding portion 2 fixes the single cell C, which is placed on the receiving portion 1, at a position facing the receiving portion 1 with the single cell C in between.

[0032] Thus, the retaining part 2 has the role of fixing the single cell C that is placed on the receiving part 1 for inspection. Furthermore, its position (the position that contacts the single cell C) is positioned opposite the single cell C with respect to the contact position of the measuring part 3 that contacts the negative electrode active material layer, which will be described later.

[0033] Specifically, in the case of a short-circuit testing device S in which a single cell C shown in Figure 1 is placed on a receiving part 1, the pressing part 2 is positioned opposite the single cell C at the position where the measuring part 3 contacts the second negative electrode active material layer 57 that contacts the receiving part 1.

[0034] The pressing unit 2 comprises a pressing plate 2a, which is shown as a rectangle in Figure 1, and a drive mechanism 2b that moves the pressing plate 2a in the Z direction. As described above, the pressing plate 2a is positioned opposite the cell C at the location where the measuring unit 3 contacts the second negative electrode active material layer 57.

[0035] By positioning the retaining plate 2a in this manner, it can contact the first negative electrode active material layer 54, and when the measuring unit 3 moves from bottom to top in the Z direction, it receives the force that comes into contact with the second negative electrode active material layer 57, thereby preventing deformation of the single cell C.

[0036] The drive mechanism 2b is responsible for moving the retaining plate 2a in the Z direction. Specifically, it is positioned upward in the Z direction until the single cell C is placed on the receiving portion 1, and once the single cell C is placed on the receiving portion 1, it descends to bring the retaining plate 2a into contact with the first negative electrode active material layer 54. After the short-circuit test for the single cell C is completed, the drive mechanism 2b raises the retaining plate 2a upward in the Z direction, separating it from the single cell C.

[0037] However, if the retaining plate 2a is pressed against the first negative electrode active material layer 54 with too much force, the first negative electrode active material layer 54 may be damaged. Also, when replacing the single cell C to be inspected, it is necessary to avoid the retaining part 2 coming into contact with the single cell C.

[0038] Therefore, the distance by which the retaining plate 2a is lowered downward in the Z direction, or the distance by which the retaining plate 2a is raised, is predetermined by taking into consideration, for example, the thickness of the retaining plate 2a and the single cell C in the Z direction.

[0039] Furthermore, any mechanism that can move the retaining plate 2a up and down in the Z direction can be used for the drive mechanism 2b, such as a rack and pinion system.

[0040] The measuring unit 3 measures the electromotive force in the single cell C by making contact with various parts of the single cell C to be inspected. As described above, since the single cell C is formed by stacking a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer on a current collector 51 in that order, a potential difference is generated between the positive electrode active material layer and the negative electrode active material layer, generating an electromotive force.

[0041] In the short-circuit inspection device S according to this embodiment of the present invention, the electromotive force (voltage value) is measured, and this electromotive force will remain constant unless, for example, there is a defect in the solid electrolyte layer or metal contamination is present.

[0042] In other words, if there are defects in each electrode layer and solid electrolyte layer, or if metal contamination is present, the voltage of cell C cannot be accurately measured. Therefore, by measuring the electromotive force of cell C, that is, the potential difference (voltage value) between the negative electrode active material layer and the current collector, it is possible to determine whether a short circuit has occurred, and based on the voltage value of cell C, it is determined whether the cell C is a good product or not.

[0043] Specifically, the measuring unit 3 in the short-circuit inspection device S according to the embodiment of the present invention has three measuring units corresponding to the contact points with the single cell C. That is, the measuring unit 3 includes a first measuring unit 31 that contacts the first negative electrode active material layer 54, a second measuring unit 32 that contacts the second negative electrode active material layer 57, and a third measuring unit 33 that contacts the current collector 51.

[0044] In this embodiment of the present invention, the measuring unit 3 consists of a first measuring unit 31 to a third measuring unit 33. Each individual measuring unit will be referred to separately, while the common elements of these three measuring units will be referred to as "measuring unit 3" as appropriate below.

[0045] Specifically, the potential difference (voltage value) measured by the first measuring unit 31 and the third measuring unit 33, and the potential difference (voltage value) measured by the second measuring unit 32 and the third measuring unit 33 are measured. The information on the measured potential difference is transmitted to the voltage measuring device 4, which will be described later.

[0046] Each measuring unit 3 is equipped with a measuring probe 3a and a drive mechanism 3b. The measuring probe 3a contacts the first negative electrode active material layer 54, the second negative electrode active material layer 57, and the current collector 51, respectively. The voltage is measured by the contact of the measuring probe 3a of each measuring unit 3 with the first negative electrode active material layer 54, etc.

[0047] The measuring probe 3a is made of metal for measuring voltage, and one end is a contact portion that contacts the first negative electrode active material layer 54, etc. This contact portion is formed in a spherical shape. As described above, the measuring probe 3a directly contacts the measuring surface of the first negative electrode active material layer 54, etc. Since the first negative electrode active material layer 54, etc., which constitutes the single cell C, is formed to be very thin, there is a possibility that the contact portion may scratch the measuring surface of the first negative electrode active material layer 54, etc. when it comes into contact with the measuring surface for measurement.

[0048] Therefore, by making the shape of the contact portion that contacts the first negative electrode active material layer 54 spherical, it is possible to prevent excessive pressure from being applied to the measurement surface, thereby preventing damage to the measurement surface.

[0049] Furthermore, for example, if the contact portion has a predetermined area such as a flat surface, the entire surface of the contact portion may not necessarily come into contact with the measuring surface, such as the first negative electrode active material layer 54. In other words, the surface of the first negative electrode active material layer 54, which serves as the measuring surface, is not necessarily formed to be flat. Therefore, if the contact portion has a predetermined area, variations in contact with the measuring surface may occur.

[0050] Therefore, as described above, the spherical shape is adopted for the contact portion of the measuring probe 3a with the single cell C, in order to make contact with the first negative electrode active material layer 54 etc. over the smallest possible area while also preventing damage. The contact time of the measuring probe 3a with the single cell C during measurement is short.

[0051] On the other hand, because the contact portion is formed in a spherical shape, the contact area with the measurement surface such as the first negative electrode active material layer 54 can be reduced, thereby suppressing variations in contact. As a result, measurement errors in multiple measurement units 3, or measurement errors in multiple single cells C to be inspected, can be reduced.

[0052] An elastic body is attached to the other end of the measuring probe 3a. Although not shown in Figure 1, etc., this elastic body biases the measuring probe 3a downward in the Z direction, and when the measuring probe 3a (contact portion) comes into contact with the measuring surface such as the first negative electrode active material layer 54, it can press the measuring probe 3a against the measuring surface with a constant force.

[0053] By providing an elastic body at the other end of the measuring probe 3a in this manner, and biasing the measuring probe 3a downward in the Z direction, the contact pressure with the first negative electrode active material layer 54 can be kept constant. Therefore, measurement errors in the multiple measuring sections 3 can be reduced.

[0054] The elastic body attached to the other end can be, for example, a spring. However, it is necessary to ensure that the measuring probe 3a is in reliable contact with the first negative electrode active material layer 54, etc., and from the viewpoint of preventing damage or deformation due to contact, a spring with sufficient spring force to achieve these objectives is selected. Various elastic bodies can be selected depending on the contact pressure of the contact portion with respect to the measuring surface.

[0055] Next, the drive mechanism 3b moves the measuring probe 3a to make contact with or not make contact with the first negative electrode active material layer 54, the second negative electrode active material layer 57, or the current collector 51. In other words, the drive mechanism 3b plays the role of moving the measuring probe 31 in the Z direction.

[0056] The drive mechanism 3b is positioned upward in the Z direction until the single cell C is placed on the receiving section 1. Once the single cell C is placed on the receiving section 1, it descends and brings the measuring probe 3a into contact with the first negative electrode active material layer 54, etc. After the short-circuit test for the single cell C is completed, the drive mechanism 3b raises the measuring probe 3a upward in the Z direction and moves it away from the single cell C.

[0057] However, if the measuring probe 3a is pressed against the first negative electrode active material layer 54 with too much force, the first negative electrode active material layer 54 may be damaged. Also, when replacing the single cell C being tested, it is necessary to avoid the measuring probe 3a coming into contact with the single cell C.

[0058] Therefore, the distance by which the measuring probe 3a is lowered downward in the Z direction, or the distance by which the measuring probe 3a is raised, is predetermined by considering, for example, the length of the measuring probe 3a and the thickness of the single cell C in the Z direction.

[0059] Furthermore, any mechanism that can move the measuring probe 3a up and down in the Z direction can be used for the drive mechanism 3b, such as a rack and pinion system.

[0060] Furthermore, by enabling the automatic operation of the drive mechanism 3b, including the drive mechanism 2b, short-circuit testing can be automated. This allows for a reduction in the test cycle time and the device cycle time.

[0061] Furthermore, the components of the measuring unit 3, other than the measuring probe 3a, may be made of insulating material. That is, as mentioned above, the measuring probe 3a is made of metal because it measures the electromotive force between the negative electrode active material layer and the current collector 51. On the other hand, since the electromotive force to be measured is a very small value, if the component of the measuring unit 3, such as the drive mechanism 3b, is made of metal, it may cause measurement errors.

[0062] Therefore, by forming the components other than the measuring probe 3a with insulating material, measurement errors can be reduced.

[0063] Furthermore, either the receiving portion 1 or the pressing portion 2, or both, may be formed from an insulating material. By adopting such a configuration, the measurement error of the short-circuit inspection device S as a whole can be further reduced.

[0064] The voltage measuring device 4 acquires the electromotive force (voltage) value of the single cell C measured by the measuring unit 3 and determines whether the single cell C to be inspected is good or bad. At the same time, it performs control on each part of the short-circuit inspection device S, such as the drive mechanisms of the holding unit 2 and the measuring unit 3.

[0065] Figure 3 is a block diagram showing the internal configuration of the voltage measuring device 4 of the short-circuit inspection device S according to an embodiment of the present invention. The voltage measuring device 4 comprises a measurement value acquisition unit 41, a determination unit 42, an information transmission unit 43, and a drive control unit 44.

[0066] The measurement value acquisition unit 41 acquires voltage values ​​indicating the potential difference of the single cell C measured by the first measurement unit 31 to the third measurement unit 33. The determination unit 42 uses the voltage values ​​acquired by the measurement value acquisition unit 41 to determine whether the single cell C being inspected has a predetermined voltage value.

[0067] In other words, the determination unit 42, for example, when making a determination, compares the potential difference between the first negative electrode active material layer 54 and the current collector 51, and the potential difference between the second negative electrode active material layer 57 and the current collector 51, acquired by the measurement value acquisition unit 41, with pre-stored threshold values.

[0068] Furthermore, the threshold value is set for each of the multiple types of single cell C being tested. In other words, the electromotive force of a single cell C differs depending on the materials that make up the single cell C, for example, but if single cell Cs use the same materials, they can be measured to have roughly the same electromotive force. Therefore, an appropriate value is selected according to the type of single cell C being tested.

[0069] Furthermore, the threshold is set with a predetermined range. This is because, even when multiple single cells C are judged using the same threshold, slight variations may occur between individual cells C during actual inspection. Therefore, if the threshold is not given a predetermined range, it will be impossible to properly determine whether a single cell C is good or bad.

[0070] Furthermore, in the embodiment of the present invention, the voltage measuring device 4 has been described on the premise that no storage device is provided inside it, and that the threshold value is stored in the determination unit 42. However, a storage device for storing the threshold value may be provided independently, for example, inside the voltage measuring device 4, or externally to which the voltage measuring device 4 can be connected.

[0071] The information transmission unit 43 may transmit the result of the pass / fail determination of the single cell C, determined by the determination unit 42, to a display device connected to the voltage measuring device 4, for example, for display. In addition, it transmits control signals to the drive mechanism, etc., from the drive control unit 44, which will be described later.

[0072] The drive control unit 44 controls the drive of each part of the short-circuit inspection device S. For example, as described above, it controls the drive mechanism 2b of the pressing part 2 and the drive mechanism 3b of the measuring part 3. It also controls the mechanism that fixes the single cell C placed on the receiving part 1, for example, by sucking air into it.

[0073] Note that the components of the voltage measuring device 4 shown in Figure 3 are listed only as the minimum necessary for explaining the operation of the short-circuit inspection device S in the embodiment of the present invention. Therefore, other components, such as the memory device described above, may also be included.

[0074] As explained above, when measuring the potential difference between the first negative electrode active material layer 54 and the current collector 51, and the potential difference between the second negative electrode active material layer 57 and the current collector 51, the drive control unit 44 in the voltage measuring device 4 controls the drive of the drive mechanism 3b. That is, the contact position of the measuring probe 3a in the single cell C is set in advance, and the drive control unit 44 controls each drive mechanism 3b so that the measuring probe 3a makes contact at each contact position according to that setting.

[0075] In this manner, the drive control unit 44 controls the drive mechanism 3b to bring the measuring probe 3a into contact with the single cell C that is to be inspected, but this position is predetermined. The position where the measuring probe 3a makes contact with the single cell C is, for example, the position shown in Figure 4 or Figure 5.

[0076] Figure 4 is a plan view showing the position where the measuring probe 3a of the measuring section 3 of the short-circuit inspection device S in an embodiment of the present invention contacts the single cell C. Figure 5 is a plan view showing another position where the measuring probe 3a of the measuring section 3 of the short-circuit inspection device S in an embodiment of the present invention contacts the single cell C.

[0077] The plan views shown in Figures 4 and 5 are the same as the plan view shown in Figure 2(B). Therefore, the first negative electrode active material layer 54 is visible in the center of the drawing, the solid electrolyte layer 53 is below it, and the current collector 51 is shown surrounding this solid electrolyte layer 53. One side 51a of the current collector 51 is visible. On the other hand, the first positive electrode active material layer 52 is hidden by the solid electrolyte layer 53 and is not visible.

[0078] In this plan view, the circular area indicates the contact point of one end of the measuring probe 3a. In both Figures 4 and 5, three contact points are shown, but the solid line on one surface 51a of the current collector 51 indicates the contact point of the third measuring probe 33a of the third measuring section 33 that contacts the current collector 51.

[0079] On the other hand, in Figures 4 and 5, two contact positions are drawn in the region of the first negative electrode active material layer 54, indicated by a solid line and a dashed line. The solid line indicates the position where the first measuring probe 31a of the first measuring unit 31, which contacts the first negative electrode active material layer 54, makes contact.

[0080] In contrast, the dashed line indicates the position where the second measuring probe 32a of the second measuring unit 32 contacts the second negative electrode active material layer 57. As is clear from Figure 1, when the single cell C is placed on the receiving unit 1, the second negative electrode active material layer 57 is in contact with the receiving unit 1, and the second measuring unit 32 makes contact with the second negative electrode active material layer 57 by moving the second measuring probe 32a from downward in the Z direction upward. Therefore, in the case of the single cell C shown in Figures 4 and 5, the contact position of the second measuring probe 32a with respect to the second negative electrode active material layer 57 is not visible. For this reason, it is indicated by a dashed line.

[0081] First, let's explain the contact positions of the first measuring element 31a and the second measuring element 32a with respect to the first negative electrode active material layer 54 and the second negative electrode active material layer 57, as shown in Figure 4. As shown in Figure 4, the contact position of the first measuring element 31a with respect to the first negative electrode active material layer 54 and the contact position of the second measuring element 32a with respect to the second negative electrode active material layer 57 do not overlap.

[0082] In other words, from the viewpoint of the movement direction of the first measuring unit 31 and the second measuring unit 32, with respect to the contact position, the first measuring unit 31 and the second measuring unit 32, which contact the first negative electrode active material layer 54 and the second negative electrode active material layer 57, are arranged so that their movement directions relative to the first negative electrode active material layer 54 and the second negative electrode active material layer 57 do not overlap.

[0083] In this way, the contact position of the first measuring element 31a on the first negative electrode active material layer 54 and the contact position of the second measuring element 32a on the second negative electrode active material layer 57 are not made to overlap in a plan view. This prevents excessive pressure from being applied to the single cell C due to the two measuring elements 3a contacting the same position on the single cell C in the Z direction, thereby preventing deformation of the single cell C.

[0084] Next, the contact positions of the first measuring probe 31a and the second measuring probe 32a with respect to the first negative electrode active material layer 54 and the second negative electrode active material layer 57, as shown in Figure 5, will be described. As shown in Figure 5, the first measuring probe 31a, which contacts the first negative electrode active material layer 54, and the second measuring probe 32a, which contacts the second negative electrode active material layer 57, are in contact with each other at a distance equal to the diameter of the contact portion of each measuring probe.

[0085] As described above, in order to avoid applying excessive pressure to the single cell C during measurement, the contact position of the first measuring probe 31a with the first negative electrode active material layer 54 and the contact position of the second measuring probe 32a with the second negative electrode active material layer 57 are made so as not to overlap.

[0086] On the other hand, if these contact points are separated too far apart, the measurement error may increase. In other words, the voltage of the electromotive force of the single cell C that is being measured in the measurement unit 3 is a very small value. Therefore, the resistance value of the connecting wire between the measurement unit 3 and the voltage measuring device 4 may also affect the measured value of the electromotive force.

[0087] Therefore, if, for example, the distance between the first measuring probe 31a and the voltage measuring device 4, and the distance between the second measuring probe 32a and the voltage measuring device 4 are different, the lengths of the connecting wires will differ, which could lead to measurement errors.

[0088] Therefore, in order to avoid applying excessive pressure to the single cell C and reduce measurement errors, the contact positions of the first measuring probe 31a and the second measuring probe 32a with respect to the negative electrode active material layer should be as close as possible while keeping them far apart. The contact positions of the first measuring probe 31a and the second measuring probe 32a shown in Figure 5 are the contact positions of the first measuring probe 31a and the second measuring probe 32a that can satisfy both of these requirements.

[0089] As described above, the shape of the contact portion where the measuring probe 3a contacts the negative electrode active material layer or the current collector 51 is formed in a spherical shape. Therefore, the closest possible contact position between the first measuring probe 31a and the second measuring probe 32a, which have such shapes, is when they are separated by the diameter of the contact portion of each measuring probe.

[0090] By having the first measuring probe 31a and the second measuring probe 32a contact the first negative electrode active material layer 54 or the second negative electrode active material layer 57 with a distance equal to the diameter of the contact area relative to the single cell C, it is possible to reduce measurement errors while avoiding the application of excessive pressure to the single cell C.

[0091] As mentioned above, the shape of the contact portion of the measuring probe 3a is spherical. Therefore, if the diameter of this sphere is different, the distance at which the contact portion of the measuring probe makes contact will change when the contact portion is separated by that diameter.

[0092] [Operation] Next, the procedure for checking for short circuits in a single cell C using a short-circuit testing device S will be explained with reference to Figure 6. Figure 6 is a flowchart showing the inspection procedure in a short-circuit testing device S according to an embodiment of the present invention.

[0093] First, the single cell C to be inspected is placed on the receiving section 1 of the short-circuit inspection device S (ST1). At this point, although the mechanism for placing the single cell C on the receiving section 1 has not been specifically explained so far, any known mechanism can be used.

[0094] Next, the placed single cell C is fixed in place by the receiving part 1 (ST2). Various methods can be considered for fixing the single cell C. For example, as described above, the receiving part 1 has a number of air holes that penetrate the receiving part 1 in the Z direction, and a method can be adopted in which the single cell C is attracted to and fixed to the receiving part 1 by drawing air through these air holes.

[0095] For this reason, for example, the drive control unit 44 of the voltage measuring device 4 may be configured to transmit a control signal to a pump that sucks in air.

[0096] The single cell C, which is placed on the receiving portion 1 in this manner, is further secured by the retaining portion 2 (ST3). As described above, the securing of the single cell C by the retaining portion 2 also has the function of preventing damage or deformation of the single cell C as a result of contact between the second negative electrode active material layer 57 and the second measuring probe 32a.

[0097] Specifically, the drive control unit 44 controls the drive mechanism 2b of the presser unit 2 so that the presser plate 2a contacts a predetermined position on the first negative electrode active material layer 54 of the single cell C on which it is placed. That is, the presser plate 2a is moved downward in the Z direction to contact the preset contact position on the first negative electrode active material layer 54.

[0098] As shown in Figure 1, this pre-set contact position is a position opposite to the position where the second measuring probe 32a contacts the second negative electrode active material layer 57 in the single cell C, with the single cell C in between.

[0099] Furthermore, when the first negative electrode active material layer 54 is placed on the receiving part 1 in a manner that it is in contact with the receiving part 1, the second measuring probe 32a will come into contact with the first negative electrode active material layer 54 in the single cell C. Consequently, the pressing plate 2a of the pressing part 2 will come into contact with the second negative electrode active material layer 57, which is located opposite the single cell C, at the position where the second measuring probe 32a comes into contact with the first negative electrode active material layer 54.

[0100] Thus, a retaining plate 2a is positioned opposite the cell C at the point where the second measuring probe 32a makes contact. On the other hand, there is no mechanism corresponding to a retaining part 2 to prevent damage or deformation of the first negative electrode active material layer 54 due to contact by the first measuring probe 31a. However, in the short-circuit inspection device S in the embodiment of the present invention, the receiving part 1 performs a function similar to that of a retaining part 2 for contact of the first measuring probe 31a with the first negative electrode active material layer 54.

[0101] After the single cell C is fixed in the receiving section 1, the first measuring probe 31a to the third measuring probe 33a are moved to predetermined positions where they are scheduled to make contact (ST4). In Figure 1, only the drive mechanism 3b for moving the measuring probe 3a in the vertical direction in the Z direction is shown, but other drive mechanisms are also provided for moving the measuring section 3 in the X and Y directions. Each measuring probe 3a is moved to its predetermined position by these drive mechanisms.

[0102] Then, the drive control unit 44 controls the drive mechanism 3b to move the measuring probe 3a downward in the Z direction and bring it into contact with each position of the single cell C (ST5). After that, it checks whether a predetermined time has elapsed (ST6).

[0103] Determining whether a predetermined time has elapsed here is difficult because, for example, vibrations when the single cell C to be inspected is placed on the receiving unit 1 may cause changes in the contact state between the measuring probe 3a and the negative electrode active material layer or the current collector 51. If the inspection is performed under such conditions, measurement errors may occur, making accurate inspection impossible.

[0104] Therefore, the test is only started after all the measuring probes 3a have made contact with the single cell C and a predetermined time has elapsed. Consequently, if the predetermined time has not elapsed (ST6 NO), the system waits until the predetermined time has elapsed.

[0105] On the other hand, if it is determined that a predetermined time has elapsed (YES in ST6), the measuring unit 3 measures the electromotive force (voltage value) (ST7). The electromotive force between the first negative electrode active material layer 54 and the current collector 51, and the electromotive force between the second negative electrode active material layer 57 and the current collector 51 are measured.

[0106] The determination of whether a predetermined time has elapsed is made, for example, by the determination unit 42 of the voltage measuring device 4, but the voltage measuring device 4 may also be configured to perform the determination by, for example, providing a timing unit.

[0107] The voltage value information representing the electromotive force measured by the measurement unit 3 is input to the measurement value acquisition unit 41, and the determination unit 42 compares it with a threshold to determine whether or not there is a short circuit in the single cell C being inspected (ST8).

[0108] Specifically, by comparing the acquired voltage value with a preset threshold, if the voltage value falls within the threshold, it is determined that no short circuit has occurred (ST9 NO), and the product is judged as good (ST10).

[0109] On the other hand, if the voltage value is determined to be outside the threshold, it is determined that a short circuit has occurred in the single cell C (YES in ST9), and the product is judged to be defective (ST11). These judgment results are then transmitted from the information transmission unit 43 to a notification device, such as a display device, for notification.

[0110] [Effects of the Example] (1) A short-circuit inspection method comprising the steps of: placing a single cell, on one side of a current collector, a first positive electrode active material layer, a first solid electrolyte layer, and a first negative electrode active material layer are stacked in that order, and on the other side of the current collector, a second positive electrode active material layer, a second solid electrolyte layer, and a second negative electrode active material layer are stacked in that order, on a receiving portion such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with the single cell; and having a measuring portion contact the single cell to measure the voltage of the single cell, wherein the measured voltage of the single cell is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector.

[0111] Because this short-circuit testing method employs such an inspection technique, it is possible to reduce the defect rate and improve the yield of batteries after stacking by performing individual short-circuit testing on each individual cell before stacking.

[0112] Furthermore, because this short-circuit inspection method is employed, high voltage is not applied when inspecting a single cell, allowing for pass / fail judgment based on short-circuit inspection without promoting dielectric breakdown.

[0113] (2) In the short-circuit inspection method described in (1) above, in the step of measuring voltage, the measuring units that contact the first negative electrode active material layer and the second negative electrode active material layer are arranged so that their directions of movement relative to the first negative electrode active material layer and the second negative electrode active material layer do not overlap.

[0114] When measuring voltage, the contact points of the measuring parts that contact the first negative electrode active material layer and the second negative electrode active material layer of the single cell do not overlap in a plan view, thus avoiding point contact from both sides of the single cell. In addition, it is possible to prevent damage and deformation of the single cell due to excessive pressure.

[0115] (3) A short-circuit inspection method as described in (1) or (2) above, wherein the measuring unit comprises a first negative electrode active material layer, a second negative electrode active material layer, and a measuring probe that contacts a current collector and has a spherical contact portion for these, and the diameter of the contact portion of the measuring probe that contacts the first negative electrode active material layer and the measuring probe that contacts the second negative electrode active material layer are separated.

[0116] By ensuring that the contact positions of the measuring probes do not overlap, and by bringing the contact positions of the first negative electrode active material layer and the second negative electrode active material layer closer together, the difference in voltage values ​​measured at each measuring section can be reduced, thereby reducing measurement errors.

[0117] (4) A short-circuit inspection method according to any of (1) to (3) above, comprising the step of placing a single cell on a receiving unit, and then a step of fixing the single cell placed on the receiving unit with a pressing unit at a position opposite the receiving unit with the single cell in between, wherein the measurement unit for measuring the voltage of the single cell is started after a predetermined time has elapsed since the measurement unit was brought into contact with the first negative electrode active material layer, the second negative electrode active material layer, and the current collector.

[0118] By making contact with the cell in this manner and then waiting a predetermined time before starting the measurement process, the movement of the cell and other components caused by the contact with the cell can be allowed to subside, resulting in more stable measurements and thus reducing measurement errors.

[0119] (5) A short-circuit inspection method according to any of (1) to (4) above, further comprising the step of determining whether the cell is good or bad using the voltage of the cell measured by the measuring unit after the measuring unit has measured the voltage of the cell.

[0120] This process allows for the determination of whether each individual cell is good or bad based on the measured voltage (electromotive force).

[0121] (6) The short-circuit inspection device in the embodiment of the present invention comprises a receiving portion in which a single cell is arranged such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with the first negative electrode active material layer or the second negative electrode active material layer, with a first positive electrode active material layer, a first solid electrolyte layer, and a first negative electrode active material layer being stacked in that order on one side of the current collector, and a second positive electrode active material layer, a second solid electrolyte layer, and a second negative electrode active material layer being stacked in that order on the other side of the current collector; a pressing portion for fixing the single cell placed in the receiving portion at a position opposite the receiving portion with the single cell in between; a measuring portion that contacts the fixed single cell and measures the voltage of the single cell; and a voltage measuring device that determines the quality of the single cell using the voltage of the single cell measured by the measuring portion, wherein the voltage of the single cell measured by the measuring portion is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector.

[0122] Because this is a short-circuit inspection device, by performing a pass / fail judgment by short-circuit inspection on individual cells before stacking, it is possible to reduce the defect rate and improve the yield of the stacked batteries.

[0123] Furthermore, by employing such a short-circuit inspection device, high voltage is not applied when inspecting a single cell, allowing for pass / fail determination based on short-circuit inspection without promoting dielectric breakdown.

[0124] (7) The short-circuit inspection device described in (6) above, wherein the measuring unit comprises a first measuring unit that contacts a first negative electrode active material layer, a second measuring unit that contacts a second negative electrode active material layer, and a third measuring unit that contacts a current collector, and the voltage measuring device calculates the voltage values ​​measured by the first measuring unit and the third measuring unit and the voltage values ​​measured by the second measuring unit and the third measuring unit.

[0125] In this way, the voltage (electromotive force) between the current collector and the first or second negative electrode active material layer can be measured. This is because the single cell being tested has a positive electrode and a negative electrode, and thus has the structure of a battery. By measuring these electromotive forces, it is possible to determine whether or not there is a short circuit.

[0126] (8) A short-circuit inspection device as described in (6) or (7) above, wherein the measuring units that contact the first negative electrode active material layer and the second negative electrode active material layer are arranged so that their directions of movement relative to the first negative electrode active material layer and the second negative electrode active material layer do not overlap.

[0127] When measuring the voltage, the contact positions of the measuring parts that contact the first negative electrode active material layer and the second negative electrode active material layer of the single cell do not overlap in a plan view. This avoids point contact from both sides of the single cell and prevents damage or deformation due to excessive pressure on the single cell.

[0128] (9) A short-circuit inspection device as described in any of (6) to (8) above, wherein the voltage measuring device determines that the product is good if the measured voltage value falls within a predetermined value set in advance, and determines that the product is defective if the measured voltage value falls outside a predetermined value set in advance, and determines that the product is defective because a short circuit has occurred in the single cell.

[0129] This process allows for the determination of whether each individual cell is good or bad based on the measured voltage (electromotive force).

[0130] (10) A short-circuit inspection device according to any of (6) to (9) above, wherein the measuring unit comprises a measuring probe that contacts a first negative electrode active material layer, a second negative electrode active material layer, and a current collector, and a drive mechanism that moves the measuring probe to contact or not contact the first negative electrode active material layer, the second negative electrode active material layer, or the current collector.

[0131] By incorporating such a measuring unit, it is possible to accurately contact the measuring device with a predetermined location on the single cell during short-circuit testing, enabling highly accurate testing.

[0132] (11) The short-circuit inspection device described in (10) above, wherein the measuring probe has a first negative electrode active material layer, a second negative electrode active material layer, and a contact portion with the current collector that is formed in a spherical shape.

[0133] The spherical shape of the contact point of the measuring probe prevents excessive pressure from being applied to the contact point, thus preventing damage during measurement. Furthermore, it reduces variations in contact at the contact point, thereby reducing measurement errors.

[0134] (12) The short-circuit inspection device described in (11) above, wherein the measuring probe that contacts the first negative electrode active material layer and the measuring probe that contacts the second negative electrode active material layer are separated by diameter at the contact portion of each measuring probe.

[0135] By ensuring that the contact positions of the measuring probes do not overlap, and by bringing the contact positions of the first negative electrode active material layer and the second negative electrode active material layer closer together, the difference in voltage values ​​measured at each measuring section can be reduced, thereby reducing measurement errors.

[0136] (13) A short-circuit inspection device according to any of (10) to (12) above, characterized in that the measuring probe comprises a first negative electrode active material layer, a second negative electrode active material layer, and an elastic body for contacting a current collector.

[0137] By incorporating an elastic body, the measuring probe can be brought into contact with the single cell with a constant force. Therefore, variations in the pressure of the measuring probe against the single cell during contact can be suppressed, thereby reducing measurement errors.

[0138] (14) A short-circuit inspection device according to any of (6) to (13) above, wherein the pressing portion is positioned opposite to the position where the measuring portion contacts the first negative electrode active material layer or the second negative electrode active material layer in the cell, with the cell in between.

[0139] By positioning the retaining part opposite the single cell in this way, damage or deformation caused by the measuring probe coming into contact with the single cell can be prevented.

[0140] (15) A short-circuit inspection device as described in any of (10) to (14) above, wherein the components of the measuring section other than the measuring probe are made of insulating material. Therefore, in the measuring section, components other than the measuring probe that is directly related to the measurement are electrically insulated. As a result, measurement errors can be reduced, and as a result, the accuracy of determining whether a single cell is good or bad can be improved.

[0141] (16) The short-circuit inspection device described in (15) above, wherein either the receiving portion or the pressing portion, or both, are made of an insulating material. Furthermore, by electrically insulating each part constituting the short-circuit inspection device, measurement errors can be reduced, and as a result, the accuracy of determining whether a single cell is good or bad can be improved. [Explanation of Symbols]

[0142] 1...Receiving part, 11...Opening, 2...Pressing part, 2a...Pressing plate, 2b...Drive mechanism, 3...Measuring part, 3a...Measuring probe, 3b...Drive mechanism, 31...First measuring part, 31a...First measuring probe, 32...Second measuring part, 32a...Second measuring probe, 33...Third measuring part, 33a...Third measuring probe, 4...Voltage measuring device, 41...Measurement value acquisition part, 42 ...Determination unit, 43...Information transmission unit, 44...Drive control unit, 51...Current collector, 51a...One side, 51b...Other side, 52...First positive electrode active material layer, 53...First solid electrolyte layer, 54...First negative electrode active material layer, 55...Second positive electrode active material layer, 56...Second solid electrolyte layer, 57...Second negative electrode active material layer, C...Single cell, S...Short circuit inspection device

Claims

1. The steps include: placing a single cell, on one side of a current collector, in which a first positive electrode active material layer, a first solid electrolyte layer, and a first negative electrode active material layer are laminated in that order, and on the other side of the current collector, in which a second positive electrode active material layer, a second solid electrolyte layer, and a second negative electrode active material layer are laminated in that order, into a receiving portion such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with it; The measurement unit includes the step of contacting the single cell and measuring the voltage of the single cell, A short-circuit inspection method characterized in that the voltage of the single cell to be measured is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector.

2. The short-circuit inspection method according to claim 1, characterized in that, in the step of measuring the voltage, the respective measuring units that contact the first negative electrode active material layer and the second negative electrode active material layer are arranged so that their directions of movement relative to the first negative electrode active material layer and the second negative electrode active material layer do not overlap.

3. The measuring unit comprises a first negative electrode active material layer, a second negative electrode active material layer, and a measuring probe that contacts the current collector and has a spherical contact portion for these layers. The short-circuit inspection method according to claim 1, characterized in that the measuring probe that contacts the first negative electrode active material layer and the measuring probe that contacts the second negative electrode active material layer are separated by diameter at the contact portion of each measuring probe.

4. After the step of placing the single cell on the receiving part, The step includes fixing the single cell, which is placed in the receiving portion, with a pressing portion at a position facing the receiving portion with the single cell in between, The short-circuit inspection method according to claim 1, characterized in that the measurement of the voltage of the single cell by the measuring unit is started after a predetermined time has elapsed since the measuring unit was brought into contact with the first negative electrode active material layer, the second negative electrode active material layer, and the current collector.

5. After the measuring unit measures the voltage of the single cell, further, The short-circuit inspection method according to claim 1, further comprising the step of determining whether the single cell is good or bad using the voltage of the single cell measured by the measuring unit.

6. A receiving portion is provided in which a single cell is formed, having a first positive electrode active material layer, a first solid electrolyte layer, and a first negative electrode active material layer laminated in that order on one side of the current collector, and a second positive electrode active material layer, a second solid electrolyte layer, and a second negative electrode active material layer laminated in that order on the other side of the current collector, such that either the first negative electrode active material layer or the second negative electrode active material layer is in contact with the receiving portion. The single cell placed in the receiving portion is secured by a retaining portion that holds the single cell in place at a position opposite the receiving portion with the single cell in between, A measuring unit that contacts the fixed single cell to measure the voltage of the single cell, The system includes a voltage measuring device that determines the quality of the single cell using the voltage of the single cell measured by the measuring unit, A short-circuit inspection device characterized in that the voltage of the single cell measured by the measuring unit is the voltage between the first negative electrode active material layer and the current collector, and the voltage between the second negative electrode active material layer and the current collector.

7. The measuring unit comprises a first measuring unit that contacts the first negative electrode active material layer, a second measuring unit that contacts the second negative electrode active material layer, and a third measuring unit that contacts the current collector. The short-circuit inspection device according to claim 6, characterized in that the voltage measuring device calculates the voltage value measured by the first measuring unit and the third measuring unit and the voltage value measured by the second measuring unit and the third measuring unit.

8. The short-circuit inspection device according to claim 6, characterized in that the measuring units that contact the first negative electrode active material layer and the second negative electrode active material layer are arranged so that their directions of movement relative to the first negative electrode active material layer and the second negative electrode active material layer do not overlap.

9. The short-circuit inspection device according to claim 6, characterized in that the voltage measuring device determines the single cell to be a good product if the measured voltage value falls within a predetermined value set in advance, and determines the single cell to be a defective product if the measured voltage value falls outside a predetermined value set in advance, and determines that a short circuit has occurred in the single cell.

10. The aforementioned measuring unit is The first negative electrode active material layer, the second negative electrode active material layer, and the measuring probe that contacts the current collector, A drive mechanism for moving the measuring probe to bring it into contact with or not into contact with the first negative electrode active material layer, the second negative electrode active material layer, or the current collector, The short-circuit inspection device according to claim 6, characterized by comprising the above.

11. The short-circuit inspection device according to claim 10, characterized in that the measuring probe has a first negative electrode active material layer, a second negative electrode active material layer, and a contact portion with the current collector that is formed in a spherical shape.

12. The short-circuit inspection device according to claim 11, characterized in that the measuring probe that contacts the first negative electrode active material layer and the measuring probe that contacts the second negative electrode active material layer are separated by diameter at the contact portion of each measuring probe.

13. The short-circuit inspection device according to claim 10, characterized in that the measuring probe comprises the first negative electrode active material layer, the second negative electrode active material layer, and an elastic body for contacting the current collector.

14. The short-circuit inspection device according to claim 6, characterized in that the pressing portion is positioned opposite to the position where the measuring portion contacts the first negative electrode active material layer or the second negative electrode active material layer in the single cell, with the single cell in between.

15. The short-circuit inspection device according to claim 10, characterized in that, of the measuring section, components other than the measuring probe are formed of insulating material.

16. The short-circuit inspection device according to claim 15, characterized in that either the receiving portion or the pressing portion, or both, are formed of an insulating material.

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