Measurement unit, measurement machine, measurement

Abstract

The invention provides a measuring unit, a measuring machine, a measuring method, and a safety evaluation method. A measurement unit according to one embodiment of the present disclosure is a unit for measuring at least one of a voltage and a current when an electrode layer in a battery is short-circuited, and comprises: a base on which the battery is placed; a needle for perforating the battery placed on the base; a holder that holds the needle and moves the needle to open a hole in the battery placed on the base; a displacement measuring device that measures the amount of displacement of the needle with respect to the base; and a first measuring device that measures at least one of the voltage and the current of the perforated battery.

Description

Technical Field

[0001] The present disclosure relates to a unit, a measuring machine, a measuring method for measuring the state change of an interlayer short circuit (internal short circuit) in a battery having a stacked structure, and a method for evaluating the safety of a battery having an interlayer short circuit. In particular, it relates to a situation in which the number of layers having internal short circuits is controlled to measure the state change and evaluate the safety. Background Art

[0002] In recent years, the use of rechargeable batteries has been increasing in various fields, including electronic devices, automobiles, and renewable energy. Such batteries may suffer from internal short circuits due to foreign matter mixed into the battery during manufacturing or foreign matter entering from the outside during use. A method for evaluating the safety of batteries when an internal short circuit occurs is known (Japanese Patent Publication No. 2023-081127).

[0003] [Prior art literature]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2023-081127 Summary of the Invention

[0006] [Problems to be solved by the invention]

[0007] In the evaluation method of Patent Document 1, a pressure fixture is used to pressurize an outer body containing an electrode group composed of a stacked positive electrode, a negative electrode, and a separator, and a small metal piece, causing the small metal piece to pierce the separator, thereby inducing an internal short circuit. The height (dimension) of the small metal piece in the direction of piercing the separator is 0.3 mm or more, so there is a concern that it may pierce a relatively large number of stacked layers of positive electrodes, negative electrodes, and separators. For example, there is a concern that it may not be possible to cause an internal short circuit in a relatively small number of layers, such as one or two layers. It is required to evaluate the safety of batteries that have internal short circuits in a relatively small number of layers.

[0008] The present disclosure is based on the above-mentioned situation, and aims to provide a measuring unit that can induce an internal short circuit in a relatively small number of layers and evaluate the safety of the battery by measuring at least one of the voltage and current of the battery that has undergone an internal short circuit.

[0009] [Technical means to solve the problem]

[0010] A measuring unit of one embodiment of the present disclosure is a unit for measuring at least one of a voltage and a current when a short circuit occurs in an electrode layer within a battery, and includes: a base for placing a battery; a needle for making an opening in the battery placed on the base; a retainer for holding the needle and moving the needle to make an opening in the battery placed on the base; a displacement measuring device for measuring the displacement of the needle relative to the base; and a first measuring device for measuring at least one of a voltage and a current of the battery through which the opening is made.

[0011] [Effects of the Invention]

[0012] The measuring unit of the present disclosure can cause an internal short circuit in a relatively small number of layers of a battery, and can measure at least one of the voltage and current of the battery caused by the internal short circuit to evaluate the safety of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 1 is a schematic front view showing a measurement unit as one embodiment of the present disclosure.

[0014] Figure 2 yes Figure 1 Schematic side view of an assay unit.

[0015] Figure 3 yes Figure 1 AA cross-section diagram.

[0016] Figure 4 yes Figure 1 Schematic front view of a needle included in an assay unit.

[0017] Figure 5 yes Figure 4 Schematic side view of a needle.

[0018] Figure 6 This is a schematic front view showing a measuring machine as one embodiment of the present disclosure.

[0019] Figure 7 This is a schematic front view showing a state in which another battery is connected to a battery to be measured in a measuring method as one embodiment of the present disclosure.

[0020] Figure 8 This is a schematic front view showing a state in which a DC power supply is connected to a battery to be measured in the above-mentioned measuring method.

[0021] Figure 9 This is a graph showing voltage changes in a battery in which an internal short circuit occurred using the above-mentioned measurement method.

[0022] Figure 10 Yes Figure 9 The graph shows the voltage change between a battery and a needle that short-circuits the battery internally.

[0023] Figure 11 This is a graph showing voltage changes of a battery in which an internal short circuit occurred, temperature changes of the battery, voltage changes between a needle that caused the internal short circuit and the battery, and displacement of the needle, using a measurement method according to one embodiment of the present disclosure.

[0024] Figure 12 This is a graph showing the voltage change of a battery with an internal short circuit, the current change between the battery with an internal short circuit and a battery connected in parallel with the battery, the temperature change of the battery with an internal short circuit, the voltage change between a needle that triggers the internal short circuit and the battery with the internal short circuit, the displacement of the needle, and the load change of the needle, using a measurement method that is another embodiment of the present disclosure.

[0025] Figure 13 This is a graph showing the relationship between the energy amount of the current rushing in from the external power supply and the energy amount of the internal short circuit alone in a battery having an internal short circuit, and the time since the internal short circuit.

[0026] Figure 14 This is a graph showing the relationship between the effective value of the current that rushes in from the external power supply into a battery in which an internal short circuit has occurred, the effective value of the current that only causes the internal short circuit, and the respective energy amounts.

[0027] [Explanation of Symbols]

[0028] 1: Measurement unit

[0029] 10: Abutment

[0030] 11: Main body

[0031] 12: Column

[0032] 13: Liang Department

[0033] 13a: Through hole

[0034] 20: needle

[0035] 21: Needle body

[0036] 22: Widening

[0037] 30: Retainer

[0038] 40: Displacement measuring device

[0039] 41: First connection part

[0040] 42: Second connection part

[0041] 43: Sensor Department

[0042] 50: Second measuring device

[0043] 51: Electrode cable

[0044] 60: Current line

[0045] 70: Shell

[0046] 100: Measuring machine

[0047] 200: Shunt

[0048] 300: DC power supply

[0049] 310: diode

[0050] 320: switch

[0051] 400: Power supply control unit

[0052] B. Ba: battery

[0053] B1: terminal DETAILED DESCRIPTION

[0054] [Description of Embodiments of the Present Disclosure]

[0055] (1) A measuring unit according to one embodiment of the present disclosure is a unit for measuring at least one of a voltage and a current when a short circuit occurs in an electrode layer within a battery, and includes: a base for mounting a battery; a needle for making a hole in the battery mounted on the base; a holder for holding the needle and moving the needle to make a hole in the battery mounted on the base; a displacement measuring device for measuring the displacement of the needle relative to the base; and a first measuring device for measuring at least one of a voltage and a current of the battery through which the hole has been made.

[0056] The measuring unit includes a displacement measuring device, which measures the displacement of a needle used to make a hole in the battery placed on the base, so that the depth of penetration of the needle into the battery can be controlled. Therefore, the number of layers penetrated by the needle in the stack of layers comprising a positive electrode layer, a separator layer and a negative electrode layer of the battery can be controlled, and a short circuit can be induced in a relatively small number of layers of the stack. In addition, by controlling the depth of penetration of the needle, the measuring unit can control the contact, hole opening and penetration of the needle with each layer. The measuring unit includes a measuring device for measuring at least one of the voltage and current of the battery through the hole (hereinafter sometimes referred to as "voltage / current"), so that the change in voltage / current of the battery that has an internal short circuit can be measured.

[0057] (2) In (1), the measuring unit may further include a second measuring device that measures at least one of the voltage and current between the battery and the needle, and the first measuring device may further measure at least one of the voltage and current between the battery and the needle. That is, the measuring unit may be configured to measure the voltage and current between the needle and the battery in addition to the voltage and current of the battery. By providing multiple measurement targets, battery safety evaluation can be performed in various aspects.

[0058] (3) In (1) or (2), the displacement measuring device may include a first connection portion connected to the needle and a second connection portion connected to the base. This allows the displacement of the needle to be measured easily and accurately.

[0059] (4) In (3), the base may include: a main body for mounting a battery; a pair of columns erected on the main body; and a beam spanned over the pair of columns at a distance from a surface of the battery mounted on the main body, wherein the second connecting portion is connected to the beam. This can improve the accuracy of the displacement measurement.

[0060] (5) In any one of (1) to (4), the apparatus may further include a control unit that controls the start and stop of movement of the needle using the holder, wherein the control unit controls the movement of the needle based on the measurement value of the first measuring device. As described above, the movement and stop of the needle can be easily and accurately performed.

[0061] (6) In any one of (1) to (5), the needle and the holder may be insulated. This can suppress measurement errors of the measuring device caused by external disturbances.

[0062] (7) In any one of (1) to (6), the apparatus may further include a current line electrically connecting the battery having the opening to the needle. This can further suppress the measurement error caused by external interference.

[0063] (8) A measuring device according to one embodiment of the present disclosure includes: the measuring unit according to any one of (1) to (7); and a housing that accommodates at least a portion of the measuring unit.

[0064] The measuring device includes the measuring unit, thereby being able to measure the voltage and current of the battery caused by an internal short circuit in a relatively small number of battery layers. Furthermore, the measuring device includes a housing that accommodates at least a portion of the measuring unit, thereby enabling the measurement to be performed while ensuring safety.

[0065] (9) A measurement method according to one embodiment of the present disclosure is a method for measuring at least one of a voltage and a current when a short circuit occurs in an electrode layer within a battery, the measurement method comprising: a step of placing a battery on a base; a step of measuring at least one of a voltage and a current of the battery placed on the base; a step of moving a needle toward the battery to be measured and making a hole; a step of bringing the needle into contact with the outermost electrode layer within the battery through the hole; and a step of stopping the movement of the needle in contact with the electrode layer.

[0066] The measurement method stops the movement of a needle that has opened a hole in a battery by bringing it into contact with the outermost electrode layer (the outermost electrode layer) within the battery. Therefore, the measurement method can measure the voltage change in the battery caused by a short circuit between one electrode layer (the outermost electrode layer) and the needle.

[0067] (10) In (9) above, in the step of measuring, at least one of the voltage and current between the needle and the battery may be further measured. By doing so, changes in voltage and current in the outermost electrode layer can be measured.

[0068] (11) In (8) or (9), the method may further include: moving the stopped needle toward the interior of the battery; making a hole in the outermost electrode layer using the moved needle; and stopping the movement of the needle that made the hole. By doing so, the change in voltage / current of the battery caused by an interlayer short circuit between the outermost electrode layer and an electrode layer adjacent to the outermost electrode layer can be measured.

[0069] (12) In any of (9) to (11), the method may further include: electrically connecting the battery to another battery, and in the step of measuring, measuring at least one of the voltage and current of the battery connected to the other battery. This allows observation of the effect of the other battery on the battery experiencing an internal short circuit.

[0070] (13) In any one of (9) to (11), the method may further include: in the step of connecting the battery to a DC power supply, in the step of measuring, measuring at least one of the voltage and current of the battery connected to the DC power supply. This allows observation of the effect of the DC power supply on the battery having an internal short circuit.

[0071] A safety evaluation method according to one embodiment of the present disclosure is a method for evaluating the safety of a battery having an internal short circuit, and includes: placing a battery on a base; connecting another battery or a DC power supply to the battery; moving a needle toward the battery placed on the base; causing the moved needle to open a hole in the battery, thereby inducing an internal short circuit; measuring a current I [A] flowing from the other battery or the DC power supply into the battery having an internal short circuit; and calculating an energy amount Ec [A] applied to the internal resistance of the battery according to the following formula 1. 2 ·s] steps.

[0072] Ec=Irms 2 ×T····(1)

[0073] Here, “Irms 2 ” is the effective value of the current I [A], and “T” is the total time the current I rushes into the battery [s].

[0074] The safety evaluation method can predict the possibility of damage to the battery due to the energy Ec applied to the battery, and thus can easily and reliably evaluate the safety of the battery.

[0075] [Details of the embodiments of the present disclosure]

[0076] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0077] [Measurement unit]

[0078] The measuring unit of one embodiment of the present disclosure measures at least one of the voltage and current when a short circuit occurs in an electrode layer in a battery. Figure 1 、 Figure 2 and Figure 3As shown, the measuring unit 1 includes: a base 10 for placing a battery B; a needle 20 for making a hole in the battery B placed on the base 10; a holder 30 for holding the needle 20 and moving the needle 20 to make a hole in the battery B placed on the base 10; a displacement measuring device 40 for measuring the displacement of the needle 20 relative to the base 10; and a first measuring device (not shown) for measuring at least one of the voltage and current of the battery B after the hole is opened. The measuring unit 1 of this embodiment includes: a control unit (not shown) for controlling the start and stop of the movement of the needle 20 using the holder 30; and a second measuring device 50 for measuring the voltage / current between the needle 20 and the battery B. The first measuring device and the second measuring device 50 of this embodiment measure the voltage. The second measuring device 50 is connected to either the positive or negative terminal B1 of the battery B and the needle 20 (refer to Figure 2 ), and measures the voltage between needle 20 and battery B (needle-battery voltage). The first measuring device is connected to the positive and negative terminals B1 of battery B (not shown) to measure the voltage of battery B.

[0079] Battery

[0080] Battery B is not particularly limited as long as it comprises a stacked body comprising a positive electrode layer, a negative electrode layer (hereinafter referred to as "electrode layers"), a separator disposed between these electrode layers for electrical insulation, and an outer casing for housing the stacked body. Examples thereof include lithium batteries and lithium-ion batteries. Battery B may contain a liquid electrolyte or may be an all-solid-state battery containing a solid electrolyte.

[0081] The laminate may be formed by laminating multiple electrode layers and multiple separators, or by laminating and winding a pair of electrode layers formed into a strip and a separator. The outer casing may be formed of a rigid material such as metal or resin, or a flexible material such as a laminate film. The shape of the battery B is not particularly limited, and may be, for example, a rectangular parallelepiped, cylindrical, or bag-shaped.

[0082] <Abutment>

[0083] The base 10 of this embodiment includes: a main body 11 for carrying a battery B; a pair of columns 12 arranged upright on the main body 11; and a beam 13 mounted on the pair of columns 12 at a distance from the surface of the battery carried on the main body 11. The main body 11 is formed into a roughly rectangular shape when viewed from above, and the pair of columns 12 are separated and arranged in the central part of the main body 11 on both sides facing each other. A through hole 13a is provided in the central part of the beam 13 when viewed from above, and a needle 20 is inserted into the through hole 13a. The main body 11 is preferably formed of an insulator on at least the surface (the surface for carrying the battery B), or an insulating member is arranged on the surface. A shape or member for fixing the carried battery B may also be provided on the surface of the main body 11.

[0084] Needle

[0085] like Figure 4 and Figure 5 As shown, needle 20 comprises a cylindrical needle body 21 and a widened portion 22 that widens when viewed from above. In needle 20, needle body 21 and widened portion 22 may be integrally formed or separately formed and fixedly connected. A portion of needle body 21 is retained by retainer 30, while the end (distal end) not retained by retainer 30 is formed into a conical or pyramidal shape with a distal angle of at least 5 degrees and within 90 degrees.

[0086] The material of the needle 20 is not particularly limited as long as it is conductive, and examples thereof include iron and stainless steel. The diameter of the needle body 21 is not particularly limited, and can be, for example, 2 mm to 5 mm.

[0087] A known thermometer such as a thermocouple may be built into the needle body 21 to measure the temperature of the battery B that has changed due to an internal short circuit.

[0088] Retainer

[0089] Holder 30 is configured to be movable in the axial direction of needle 20, retaining and moving needle 20 for drilling a hole in battery B. Needle 20 and holder 30 are preferably insulated. By insulating needle 20 and holder 30, external interference (noise) with the first and second measuring devices 50 during voltage measurement can be suppressed. The means for providing insulation is not particularly limited; an insulating member may be disposed on the portion of holder 30 that retains needle 20, or an insulating coating may be formed on the portion that retains needle 20.

[0090] Displacement Measuring Device

[0091] The displacement measuring device 40 of this embodiment includes a sensor portion 43, a first connecting portion 41, and a second connecting portion 42, one end of which is connected to the sensor portion 43 and extends in the same direction. The displacement measuring device 40 is a so-called clip-type strain gauge. The first connecting portion 41 is connected to the needle 20, and the second connecting portion 42 is connected to the base 10. Specifically, the first connecting portion 41 is connected to the widened portion 22, and the second connecting portion 42 is connected to the beam portion 13. The sensor portion 43 is electrically connected to the control unit and transmits the measured displacement.

[0092] An engaging portion (not shown) that engages with the other end portions (terminal ends) of the first connecting portion 41 and the second connecting portion 42 is preferably formed in the central portion of the beam portion 13 and the widening portion 22. The engaging portion is formed, for example, as a notch, a hook, etc., so as to hold the terminal ends. An engaged portion (not shown) that engages with the engaging portion may also be formed at the terminal ends. By engaging the terminal ends with the engaging portion, the widening portion 22 and the beam portion 13 can easily hold the displacement measuring device 40 and can measure the displacement amount with high precision.

[0093] The number of displacement measuring devices 40 provided in the measurement unit 1 can be one, but preferably multiple. By providing multiple displacement measuring devices 40, the displacement of the needle 20 can be measured with high accuracy. In this embodiment, two displacement measuring devices 40 are provided, and are arranged such that their first connecting portion 41 and second connecting portion 42 face each other.

[0094] The displacement measuring device 40 is preferably located near the distal end of the needle 20. Therefore, the widened portion 22 of the needle body 21 of the needle 20 is preferably located near the distal end of the needle body 21. By arranging the displacement measuring device 40 near the distal end of the needle body 21, measurement errors caused by deformation of the needle 20, such as bending, when the needle 20 presses against the battery B, can be suppressed.

[0095] The resolution of the displacement measuring device 40 is preferably equal to or less than the thickness of the electrode layer. The upper limit of the resolution is preferably 0.0070 mm / μ, more preferably 0.0050 mm / μ, and even more preferably 0.0025 mm / μ. When the resolution is below the upper limit, one electrode layer can be short-circuited. The lower limit of the resolution is not particularly limited and can be, for example, 0.0001 mm / μ.

[0096] <Measurement Equipment>

[0097] The first measuring device is connected to the positive and negative terminals B1 of battery B to measure the voltage of battery B. A second measuring device 50 is connected to either the positive or negative terminal B1 of battery B and to pin 20 to measure the pin-to-battery voltage. If the first measuring device can measure voltage using two different systems, the second measuring device may not be included. The first and second measuring devices 50 (hereinafter referred to simply as "measuring devices") are not particularly limited, and known voltmeters may be used.

[0098] Regarding the voltage between the needle and the battery, when the outermost electrode layer of the stack housed in the battery B is the positive electrode, the positive electrode cable of the measuring instrument is connected to the needle 20, and the negative electrode cable of the measuring instrument is connected to the negative electrode terminal B1 of the battery B. When the outermost electrode layer is the negative electrode, the negative electrode cable of the measuring instrument is connected to the needle 20, and the positive electrode cable of the measuring instrument is connected to the positive electrode terminal of the battery B. Figure 2 , the positive electrode cable and the negative electrode cable are both represented as electrode cables 51 .

[0099] The measuring unit 1 preferably includes a current line 60 (refer to Figure 1 Specifically, it is preferable to connect the needle 20 to the surface (outer surface) of the outer casing of the battery B using a current line 60. This can suppress noise generated by the movement of the needle 20, thereby enabling high-precision voltage measurement.

[0100] <Control Department>

[0101] The control unit instructs the start and stop of the movement of the holder 30 and receives the displacement amount measured by the displacement measuring device 40. The control unit is preferably electrically connected to the measuring device and receives the voltage value measured by the measuring device.

[0102] The control unit preferably controls the movement of the needle 20 based on the measurement value of the measuring device. Specifically, the control unit preferably determines whether to stop or start the movement of the needle 20 (release the stop) based on the voltage value measured by the measuring device, and instructs the holder 30 to move or stop. The voltage value used to control the stop or start of the movement of the needle 20 can be set to any value.

[0103] [Measuring machine]

[0104] like Figure 6As shown, the measuring machine 100 includes: a measuring unit 1, and a housing 70 that accommodates at least a portion of the measuring unit 1. The housing 70 is a rectangular parallelepiped box with an opening on one side and a cover (not shown) that seals the opening. A through hole (not shown) is provided on the other side of the housing 70 or the cover, and the retainer 30 is inserted through the through hole, so that a portion of the retainer 30 is accommodated in the housing 70. The measuring device may not be accommodated in the housing 70. By short-circuiting the battery B inside the housing 70, the safety of the operation can be improved. A thermometer may also be arranged in the housing 70 to measure the temperature change inside the housing 70.

[0105] [Measurement method]

[0106] The measurement method includes the steps of placing a battery B on a base 10; measuring at least one of the voltage and current of the battery B placed on the base 10; moving a needle 20 toward the battery B whose voltage is being measured to create a hole; bringing the needle 20 into contact with the outermost electrode layer within the opened battery B; and stopping the movement of the needle 20 in contact with the electrode layer. During the measurement step, it is preferred that at least one of the voltage and current between the needle and the battery be measured.

[0107] The measuring method may further include the steps of: moving the stopped needle 20 toward the interior of the battery B; and stopping the movement of the needle 20 that has penetrated the electrode layer. The measuring method is preferably performed using the measuring unit 1.

[0108] <Loading steps>

[0109] The placement step preferably includes a process of housing the measurement unit 1, excluding the measuring device, in the housing 70. Furthermore, the placement step includes a process of connecting the measuring device to the positive and negative terminals of the battery B placed on the base 10, and a process of connecting the displacement measuring device 40 to the control unit. It may also include a process of connecting the measuring device to one of the terminals B1 of the battery B between the needle 20 and the measuring device. If the needle 20 includes the thermometer, the process may also include connecting the thermometer to the control unit.

[0110] <Measurement Procedure>

[0111] In the measurement step, the voltage and current of the battery B placed on the base 10 are measured. In this embodiment, the voltage is measured. The measurement preferably includes the voltage of the battery B and the voltage between the needle and the battery.

[0112] <Drilling steps>

[0113] In the hole-making step, the needle 20 is moved toward the battery B to make a hole. Specifically, a hole is made in the outer casing of the battery B and in the separator (outermost separator) disposed between the outer casing and the outermost electrode layer.

[0114] The speed of needle 20 moving toward battery B is not particularly limited. The upper limit of the speed may be, for example, 0.10 mm / s, 0.05 mm / s, or 0.01 mm / s. The lower limit of the speed is not particularly limited, but may be, for example, 0.001 mm / s. By setting the speed within this range, the accuracy of measuring the displacement of needle 20 can be improved, and needle 20 can be easily stopped.

[0115] The hole-opening step may include a first movement process in which the needle 20 approaches the battery B, and a second movement process in which the needle 20 opens a hole in the outer casing and the outermost separator. In the first movement process, the needle 20 may be moved at a relatively high speed until the distance between the battery B and the tip of the needle 20 is, for example, 1 mm to 5 mm. Following the first movement process, in the second movement process, the needle 20 may be moved within the speed range to open a hole in the outer casing and the outermost separator.

[0116] <Contact steps>

[0117] In the contact step, needle 20 is brought into contact with the outermost electrode layer. The short circuit caused by contact between the outermost electrode layer and needle 20 causes changes in the battery voltage and the needle-to-battery voltage. By measuring these changes, the initial manifestation of the short circuit can be observed. A thermometer can also be built into needle 20 to measure the temperature change of the short-circuited battery B.

[0118] <Stop Step>

[0119] In the stopping step, the movement of the needle 20 in contact with the electrode layer is stopped. After the contact step, the movement of the needle 20 may be stopped after a predetermined time has passed, or the movement of the needle 20 may be stopped under the control of the control unit when the voltage measured by the measuring device reaches a predetermined value.

[0120] This measurement method can measure the voltage, etc., of battery B when only the outermost electrode layer is short-circuited. This measurement method can observe the behavior of battery B when a short circuit occurs at the smallest unit, making it suitable for evaluating the safety of battery B.

[0121] <Move again>

[0122] In the re-moving step, needle 20, which had stopped moving, is moved again toward the interior of battery B. Specifically, needle 20, which had stopped in contact with the outermost electrode layer, is moved again to penetrate the outermost electrode layer. The re-moving of needle 20 causes changes in the battery voltage and the needle-to-battery voltage, and these changes can be measured.

[0123] <Stop again>

[0124] In the re-stopping step, the movement of the needle 20 that has penetrated the outermost electrode layer is stopped again. The re-stopping may be performed by penetrating the outermost electrode layer or by contacting an electrode layer adjacent to the outermost electrode layer.

[0125] The measuring method includes the re-moving step and the re-stopping step, and can measure the voltage of battery B when a hole is opened in the outermost electrode layer and the hole is expanded starting from the contact between the needle 20 and the outermost electrode layer, and can then penetrate the hole to measure the voltage of battery B caused by a short circuit between only the outermost electrode layer and the electrode layer adjacent to the outermost electrode layer.

[0126] <Procedure for connecting other batteries>

[0127] The measurement method described above is a method for measuring the voltage change caused by the internal short circuit of a single battery, but the measurement method can also be used to connect multiple batteries and measure the voltage / current changes when an internal short circuit occurs in one of the batteries. Specifically, Figure 7 As shown, the measuring method may further include: a step of connecting the battery B to another battery Ba, and in the step of measuring, measuring the voltage / current of the battery B connected to the other battery Ba. The other battery Ba may be connected in parallel with the battery B (refer to Figure 7 ), or they may be connected in series (not shown). The number of other batteries Ba connected to battery B is not particularly limited, and may be one or more.

[0128] In products using batteries, batteries are sometimes installed in the form of a battery pack formed by connecting multiple batteries in parallel or in series, or a battery unit formed by connecting multiple battery packs. When an internal short circuit occurs in one of the multiple connected batteries and the voltage drops, current rushes in (enters) from the other batteries. Therefore, the battery with the internal short circuit may sometimes cause an event (explosion, rupture, fire, smoke, damage, electrolyte leakage, etc.). By connecting another battery Ba and measuring the voltage / current of the battery B that has intentionally caused a short circuit, the signs, occurrence, and process of the event in battery B can be observed. In the step of measuring, it is also advisable to measure the voltage between battery B and needle 20, the voltage of the other battery Ba, the current between battery B and the other battery Ba, the temperature of battery B (surface temperature, internal temperature), etc. By increasing the measurement objects, information related to the event (changes in battery B) can be observed in detail, and the ease and accuracy of evaluating the safety of the battery pack, the battery unit or the product can be improved. In measuring the current between the battery B and the other battery Ba, it is preferable to use the shunt 200 .

[0129] The internal short circuit of battery B may be the contact between the outermost electrode layer of battery B and the needle 20, or the short circuit between the needle 20 and the outermost electrode layer (positive electrode layer or negative electrode layer) of battery B and the adjacent electrode layer (negative electrode layer or positive electrode layer) (short circuit with a single positive electrode layer and a single negative electrode layer), or the short circuit between the needle 20 and three or more electrode layers.

[0130] <DC power supply connection procedure>

[0131] like Figure 8 As shown, the measurement method may further include connecting battery B to a DC power supply 300, and in the measurement step, measuring the voltage and current of battery B connected to the DC power supply 300. If an internal short circuit occurs in one or a portion of the batteries in a product equipped with the battery pack or battery cell, and high output is required for the product, a large current may rush from other batteries into the battery experiencing the internal short circuit, potentially triggering the event and causing damage to the battery pack, battery cell, or product. By connecting battery B to a DC power supply 300 and rushing a constant current into battery B to intentionally induce an internal short circuit (constant-current inrush during internal short circuit (CISC)), the voltage and current of battery B, the battery pack, battery cell, or product can be measured (CISC test).

[0132] In the measurement method (CISC test), it is preferable to connect battery B and DC power supply 300 in parallel, and electrically connect the power supply control unit 400 to battery B and DC power supply 300. When the power supply control unit 400 detects a voltage drop caused by an internal short circuit of battery B, it instructs the DC power supply 300 to supply current. The DC power supply 300 can flow current immediately after the internal short circuit of battery B. Specifically, the DC power supply 300 allows the current to flow in within a few milliseconds (msec) to hundreds of milliseconds from the internal short circuit of battery B. There is no particular limitation on the current value flowing to battery B, and it can be determined by considering the maximum current value of the product equipped with battery B, wiring resistance, etc. The lower limit of the current value may be, for example, 1A, 10A, or 100A. The upper limit of the current value may be, for example, 3000A.

[0133] In the CISC test, a diode 310 is preferably provided in the wiring to protect the DC power supply 300 from reverse current. In addition, a switch 320 is preferably provided to stop the CISC test in an emergency.

[0134] By connecting the DC power supply 300 to the battery B and measuring the voltage and current of the battery B with an intentional internal short circuit, the safety of the battery B, the battery pack, the battery cell, or the product can be evaluated.

[0135] [Safety evaluation method]

[0136] The safety evaluation method is a method for evaluating the safety of a battery having an internal short circuit, and includes: placing the battery on a base; connecting another battery or a DC power supply to the battery; moving a needle toward the battery placed on the base; causing the moved needle to open a hole in the battery, thereby inducing an internal short circuit; measuring a current I [A] flowing from the other battery or the DC power supply into the battery having an internal short circuit; and calculating an energy amount Ec [A] applied to the internal resistance of the battery according to the following formula 1. 2 ·s] steps.

[0137] Ec=Irms 2 ×T····(1)

[0138] Here, “Irms 2 ” is the effective value of the current I [A], and “T” is the total time the current I rushes into the battery [s].

[0139] The safety evaluation method evaluates safety based on the amount of energy Ec applied to the internally short-circuited battery B by another battery Ba or DC power supply 300. The current I that rushes into the internally short-circuited battery B from another battery Ba or DC power supply 300 may have a complex current waveform, making it difficult to easily calculate the amount of heat (Joule heat) generated in battery B. In the safety evaluation method, even when the inrush current has a complex current waveform, the evaluation is based on the amount of energy Ec applied to battery B, making it possible to quantitatively assess the potential for damage to battery B.

[0140] First, the effective value Irms [A] of the inrush current I [A] flowing to the internally short-circuited battery B is calculated according to the following formula 2.

[0141] [Formula 2]

[0142]

[0143] Here, "t" is the time [s] that has passed since the internal short circuit of battery B occurred.

[0144] When the above-mentioned formula 2 is expanded, it becomes the following formula 3, where the left side is the product of the square of the effective value and time.

[0145] [Formula 3]

[0146]

[0147] When the internal resistance (internal resistance) of battery B in which an internal short circuit has occurred is expanded as R, the following equation 4 is obtained.

[0148] (Irms 2 ×R) / (R×T)=(Ws×T) / R=J / R····(4)

[0149] Here, “Ws” is the power generated by the inrush current I [W], and “J” is the heat generated by the inrush current I [J].

[0150] Based on the above, the amount of energy Ec (Formula 1) applied to the resistor R when the internal short circuit of the battery B occurs can be used as a quantitative evaluation of the internal short circuit of the battery B. Figure 13 and Figure 14 , shows the results of a CISC test using a plurality of laminated cell batteries (maximum capacity 5.0 Ah) having NCM811 as the positive electrode and graphite as the negative electrode, and applying an inrush current I of 1 A to 200 A to each of the laminated cell batteries via a DC power supply.

[0151] Figure 13The dot in the figure indicates a damaged battery, and the double-dotted line is its approximate line.

[0152] By before reaching the double-dotted line ( Figure 13 The inrush current is cut off (below the double-dashed line in the figure), thereby preventing the battery from being damaged (incident).

[0153] Figure 14 The dot in the figure indicates a damaged battery, and the double-dotted line is its approximate line.

[0154] By before reaching the double-dotted line ( Figure 14 By cutting off the inrush current (to the left of the double-dotted chain line in FIG), damage to the battery can be prevented.

[0155] In the safety evaluation method, the amount of energy Ec applied to battery B, which has experienced an internal short circuit, until the event occurs is calculated. If the current (energy) flowing into battery B is cut off before the amount of energy applied to battery B reaches the calculated Ec, the event in battery B can be prevented.

[0156] In the safety evaluation method, the energy amount Ec can be calculated based on the actual behavior of the current I caused by the internal short circuit of battery B (measurement), or it can be calculated through simulation. The calculated value obtained from the measurement can be compared with the calculated value from the simulation. By using the energy amount Ec calculated through the simulation, the number of measurements (tests) can be reduced, allowing for efficient evaluation. Furthermore, the accuracy of the energy amount Ec calculated through the measurement can be improved.

[0157] The safety evaluation method simulates the condition of battery B used as part of the battery pack, the battery cell or the product, and causes an internal short circuit in battery B. Therefore, the safety of battery B when an internal short circuit occurs under the same conditions and environment as those in actual use can be evaluated.

[0158] [Other embodiments]

[0159] The embodiments do not limit the structure of the present invention. Therefore, the embodiments can omit, replace or add components of each part of the embodiments based on the description of this specification and technical common sense, and all of these should be interpreted as falling within the scope of the present invention.

[0160] In the above embodiment, the displacement measuring device is described as a clip-on strain gauge. However, the displacement measuring device is not particularly limited as long as it can measure the displacement amount of the needle.

[0161] The base is not limited to the above-described structure and shape as long as it is configured to be able to place a battery and measure the displacement of the needle.

[0162] [Example]

[0163] Hereinafter, the present disclosure will be described in more detail through examples, but the present disclosure is not limited to these examples.

[0164] [Example 1]

[0165] Prepare a battery with an initial voltage of 4.2V and a measuring unit 1, and place the battery on a base 10. Place the measuring unit 1 except the voltage measuring device in a housing 70. Move the needle 20 to make a hole in the battery and make it contact with the outermost electrode layer. The displacement measuring device 40 uses a displacement measuring device with a resolution of 0.0025mm. The control unit is set as follows: when the voltage between the needle and the battery is 4.0V, the movement of the needle 20 is stopped; after a predetermined time has passed at a voltage between the needle and the battery of 4.0V, the stopped needle 20 is moved again; and when the voltage between the needle and the battery is 4.05V, the movement of the needle 20 is stopped again. The change in battery voltage caused by the contact is shown in FIG. Figure 9 , the change in the voltage between the needle and the battery is shown in Figure 10 .from Figure 9 It can be seen that the battery voltage drops due to the short circuit caused by the contact between the outermost electrode layer and the needle 20. Figure 10 It can be seen that the voltage between the needle and the battery decreases due to the resumption of movement (movement again). Figure 10 In the example, before the outer casing of the battery comes into contact with the needle 20 , the voltage between the needle and the battery has a waveform disturbance, but the disturbance is noise (spatial noise) caused by the movement of the needle 20 .

[0166] [Example 2]

[0167] Prepare a battery with an initial voltage of 4.2V and a measuring unit 1, and place the battery on a base 10. Place the measuring unit 1 except the voltage measuring device in a housing 70, make a hole with a needle 20 and make it contact with the outermost electrode layer. A thermometer is built into the needle 20, and the temperature change of the battery is measured while measuring the voltage change. The control unit is set as follows: when the voltage between the needle and the battery is 4.0V, the movement of the needle 20 is stopped; after a prescribed time has passed when the voltage between the needle and the battery is 4.2V, the stopped needle 20 is moved again; the movement of the needle 20 is stopped again by the needle 20 contacting the electrode layer adjacent to the outermost electrode layer; and after a prescribed time has passed since the stop again, the needle 20 is separated from the battery. The results are shown in Figure 11As can be seen, the battery temperature did not change significantly when the outermost electrode layer and needle 20 were short-circuited. However, the battery temperature rose sharply due to the short-circuit between the outermost electrode layer and the adjacent electrode layer (interlayer short). Furthermore, the battery temperature recovered when the battery voltage and the needle-to-battery voltage reached approximately 0V. When needle 20 was separated from the battery, the battery voltage returned to approximately 3.7V.

[0168] [Example 3]

[0169] A battery (test cell) with a reduced charge capacity to an initial voltage of 3.67V, intended to be a battery to cause an internal short circuit (parallel cell), a battery (parallel cell) electrically connected in parallel to the test cell with an initial voltage of 3.67V, and a measuring unit 1 were prepared. Furthermore, a voltage measuring device for measuring the voltage of the parallel cell and a current measuring device for measuring the current of the test cell were prepared. The test cell was placed on a base 10, and the measuring unit 1, excluding the voltage measuring device, was placed within a housing 70. A hole was opened in the test cell using a needle 20, bringing it into contact with the outermost electrode layer.

[0170] The control unit is set as follows: when the voltage between the needle and the battery reaches 2.5V, the movement of the needle 20 is stopped; after a predetermined time has passed when the movement of the needle 20 has stopped and the battery voltage reaches the initial voltage (3.67V), the stopped needle 20 is moved again; and when the battery voltage drops by 0.15V (to 3.52V), the movement of the needle 20 is stopped again.

[0171] A shunt is placed on the wire connecting the negative terminals of the parallel battery and the test battery, and the current between the test battery and the parallel battery is measured using the current measuring device. Figure 12 "6-Cell Current"), the voltage of the parallel-connected cells is also measured ( Figure 12 The temperature in the test cell is measured by a built-in thermometer in the needle 20 ( Figure 12 "3-Battery temperature"), and further, two thermometers were arranged near the portion of the test battery that was opened by the needle 20 to measure the change in the surface temperature of the test battery ( Figure 12 "1-Battery surface temperature" and "2-Battery surface temperature"). In addition, a thermometer is arranged in the housing 70 to measure the temperature change in the housing 70 ( Figure 12 In addition, the load applied by the needle 20 to the test battery was measured ( Figure 12 5-load), and the displacement of the retainer 30 ( Figure 12These measured values, as well as the voltage of the test cell ( Figure 12 "7-Battery Voltage"), Pin-Battery Voltage ( Figure 12 "9-pin battery voltage") and the displacement of pin 20 ( Figure 12 The measured values ​​of "11-needle displacement") are shown in the graph Figure 12 .

[0172] observe Figure 12 It can be seen that after the needle 20 is stopped again, there is a difference between the displacement of the needle 20 and the displacement of the retainer 30. The reason for this is believed to be that the displacement of the retainer 30 includes various displacements caused by factors such as thermal expansion of the battery, base 10, needle 20, etc., making it difficult to determine the displacement with high accuracy. Therefore, it is preferable to measure the displacement of the needle 20 directly, and more preferably to measure it at a location as close to the battery as possible. At 500sec to 1400sec and 1800sec to 2400sec, the voltage between the needle and the battery is disturbed, but it can be observed that such disturbance is meaningful for the evaluation of batteries with internal short circuits. In addition, the current between the batteries is 0A before 2600sec because the connection between the test battery and the parallel battery is disconnected.

[0173] [Industrial Applicability]

[0174] The measuring unit disclosed herein can easily and accurately measure voltage changes caused by an internal short circuit in a battery and can therefore be suitably used for evaluating battery characteristics at battery development and manufacturing sites.

Claims

1. A measuring unit for measuring at least one of a voltage and a current when a short circuit occurs in an electrode layer within a battery, the measuring unit comprising: A base for placing batteries; a needle for making a hole in the battery placed on the base; a holder for holding the needle and moving the needle to open a hole in the battery placed on the base; a displacement measuring device for measuring the displacement of the needle relative to the base; as well as The first measuring device measures at least one of a voltage and a current of the battery having the hole opened.

2. The measuring unit according to claim 1, wherein Also includes: The second measuring device, The second measuring device measures at least one of a voltage and a current between the battery and the needle. The first measuring device can further measure at least one of a voltage and a current between the battery and the needle.

3. The measuring unit according to claim 1, wherein The displacement measuring device includes a first connection portion connected to the needle and a second connection portion connected to the base.

4. The measuring unit according to claim 3, characterized in that The base station has: A main body, used for carrying batteries; a pair of columns erected on the main body; and The beam portion is arranged across the pair of pillar portions at a distance from the surface of the battery placed on the main body. Wherein, the second connecting portion is connected to the beam portion.

5. The measuring unit according to claim 1, wherein Also includes: Control Department, The control unit controls the start and stop of movement of the needle by the holder. Here, the control unit controls the movement of the needle based on the measurement value of the first measuring device. The measuring unit according to claim 1 , wherein: The needle is insulated from the retainer.

7. The measuring unit according to claim 1, wherein Also includes: Current lines, The current wire electrically connects the opened battery to the needle.

8. A measuring machine, characterized in that: include: The measuring unit according to any one of claims 1 to 7; as well as The housing accommodates at least a portion of the measuring unit.

9. A method for measuring at least one of a voltage and a current when a short circuit occurs in an electrode layer within a battery, the method comprising: The step of placing the battery on a base; a step of measuring at least one of a voltage and a current of a battery mounted on the base; The step of moving the needle toward the battery to be measured and performing a hole opening; a step of bringing the needle into contact with the outermost electrode layer in the opened battery; and a step of stopping the movement of the needle in contact with the electrode layer.

10. The measuring method according to claim 9, characterized in that In the step of measuring, at least one of a voltage and a current between the needle and the battery is further measured.

11. The measuring method according to claim 9, characterized in that Also includes: a step of causing the needle, which has stopped moving, to move toward the interior of the battery again; a step of making a hole in the outermost electrode layer by using the needle moved again; as well as The step of stopping the needle that has made the hole again from moving again.

12. The measuring method according to any one of claims 9 to 11, characterized in that Also includes: In the step of electrically connecting the battery to other batteries, In the step of measuring, at least one of a voltage and a current of the battery to which the other battery is connected is measured.

13. The measuring method according to any one of claims 9 to 11, characterized in that Also includes: In the step of connecting the battery to a DC power supply, In the measuring step, at least one of a voltage and a current of the battery connected to the DC power supply is measured.

14. A safety evaluation method for evaluating the safety of a battery that has experienced an internal short circuit, the method comprising: The step of placing the battery on a base; The step of connecting the battery to other batteries or a DC power source; a step of moving a needle toward the battery placed on the base; a step of causing the moved pin to open a hole in the battery, thereby inducing an internal short circuit; a step of measuring a current I [A] rushing from the other battery or the DC power supply into the battery in which an internal short circuit has occurred; as well as The energy amount Ec[A] applied to the internal resistance of the battery is calculated according to the following formula 1: 2 ·s] steps, Ec=Irms 2 ×T…(1) Here, "Irms 2 " is the effective value of the current I [A], "T" is the total time the current I rushes into the battery [s].

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