Method for self-discharge inspection of power storage device and method for manufacturing power storage device

Abstract

Provided are a self-discharge inspection method for an electricity storage device and a manufacturing method for an electricity storage device, which can shorten the inspection time of the self-discharge of the electricity storage device. The self-discharge inspection method for an electricity storage device (1) includes the following steps: a voltage continuous application step (S7, S27) of continuously applying, from an external power supply (EP1, EP2), a continuous power supply voltage (VPc) of a fixed size higher than a first device voltage (VBso) to the electricity storage device (1) pre-charged to the first device voltage (VBso); a current detection step (S8, S28) of detecting a power supply current (IP, IP(n)) flowing through the electricity storage device (1) from the external power supply (EP1, EP2); and a determination step (S10) of determining the self-discharge state of the electricity storage device (1) based on the detected power supply current (IP, IP(n)).

Description

Technical Field

[0001] The present invention relates to a self-discharge inspection method for an electricity storage device for determining a self-discharge state of the electricity storage device and a method for manufacturing an electricity storage device including the self-discharge inspection method. Background Art

[0002] During the manufacturing of electrical storage devices such as lithium-ion secondary batteries, metallic foreign matter such as iron and copper may be introduced into the interior of the electrode body, causing self-discharge due to internal short circuits. Therefore, during the manufacturing process of electrical storage devices, it is sometimes necessary to determine the self-discharge status, such as the presence of internal short circuits and the magnitude of the self-discharge current.

[0003] As a method for inspecting the self-discharge of a storage device, for example, the following method is known. Specifically, the pre-detection device voltage of a pre-charged storage device is measured in advance, and a power supply voltage equal to the pre-detection device voltage is continuously applied to the storage device from an external power supply. Consequently, the power supply current flowing from the external power supply through the storage device gradually increases from zero, reaching a level equal to the self-discharge current of the storage device and then stabilizing. Therefore, this power supply current is detected, and the magnitude of the self-discharge current of the storage device is determined based on the detected power supply current. Patent Document 1 (see the claims of Patent Document 1, etc.) is cited as an example of related prior art.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2019-16558 Summary of the Invention

[0005] Problems to be solved by the invention

[0006] However, even in the above-described self-discharge inspection method, it takes time until the magnitude of the power supply current becomes substantially stable, and therefore there is a demand for further shortening the inspection time.

[0007] The present invention has been made in view of the above-mentioned current situation, and an object of the present invention is to provide a self-discharge inspection method for an electricity storage device capable of shortening the inspection time for self-discharge of the electricity storage device, and a method for manufacturing an electricity storage device including the self-discharge inspection method.

[0008] Solutions for solving problems

[0009] (1) One embodiment of the present invention for solving the above-mentioned problem is a method for checking the self-discharge of an electric storage device, which includes the following steps: a voltage continuous application step, in which a continuous power supply voltage of a fixed magnitude and higher than the first device voltage is continuously applied from an external power supply to the electric storage device that has been previously charged to a first device voltage; a current detection step, in which a power supply current flowing from the external power supply through the electric storage device is detected; and a determination step, in which a self-discharge state of the electric storage device is determined based on the detected power supply current.

[0010] In the above-described method for inspecting self-discharge of an energy storage device, a continuous voltage application step, a current detection step, and a determination step are performed, in which a continuous power supply voltage is continuously applied to the energy storage device charged to a first device voltage. Furthermore, the continuous power supply voltage continuously applied during the continuous voltage application step is higher than the first device voltage and has a constant magnitude. Therefore, unlike conventional methods, the power supply current can flow to the energy storage device under test from the very beginning of the continuous voltage application step.

[0011] Here, (I) if the magnitude of the power supply current flowing through the energy storage device at the beginning of the continuous voltage application process due to the continuous application of the power supply voltage is equal to the "self-discharge current" flowing in the energy storage device itself, then a stable power supply current equal to the self-discharge current will continue to flow from the beginning of the continuous voltage application process.

[0012] On the other hand, (II) when the power supply current flowing through the energy storage device at the beginning of the continuous voltage application process is "less than the self-discharge current" due to continued application of the power supply voltage, the power supply current gradually approaches the self-discharge current of the energy storage device, and stabilizes after reaching a level equal to the self-discharge current. This change is similar to the change in the self-discharge test of the conventional method, which occurs when a power supply current of a certain magnitude flows over time. Therefore, compared to the conventional method, the power supply current stabilizes in a shorter time.

[0013] On the other hand, (III) when the magnitude of the power supply current flowing through the energy storage device at the beginning of the continuous voltage application process is "greater than the self-discharge current" due to the continued application of the power supply voltage, the portion of the power supply current that exceeds the self-discharge current is used to charge the energy storage device (its capacitive component). Consequently, the open circuit voltage (capacitive component voltage) of the energy storage device, which was at the first device voltage at the beginning of the continuous voltage application process, increases due to charging. Conversely, the power supply current (the portion used for charging) decreases due to the increase in the open circuit voltage of the energy storage device. Furthermore, when the magnitude of the new self-discharge current of the energy storage device, which has increased due to the increase in the open circuit voltage, becomes equal to the flowing power supply current, neither charging the energy storage device (capacitive component) nor self-discharging the energy storage device (capacitive component) occurs. In other words, the power supply current stabilizes after decreasing to the new magnitude of the self-discharge current. Furthermore, the increase in the open circuit voltage of the energy storage device and the increase in the self-discharge current occur rapidly. That is, compared to the rate of increase of the power supply current in conventional methods, the power supply current stabilizes after a rapid decrease.

[0014] In this way, in either case, compared with the previous inspection method in which a continuous power supply voltage equal to the first device voltage is continuously applied from the beginning to gradually increase the power supply current from 0, the power supply current flowing through the tested storage device can be stabilized earlier, thereby performing the self-discharge inspection earlier.

[0015] As will be described later, the self-discharge inspection method for an electricity storage device can be performed not only during the manufacturing process of the electricity storage device but also on an electricity storage device that is being used or already installed in a vehicle or placed on the market.

[0016] Examples of the “electricity storage device” include secondary batteries such as lithium ion secondary batteries, and capacitors such as electric double layer capacitors and lithium ion capacitors.

[0017] The first device voltage is an open circuit voltage generated between the terminals of the power storage device when the current flowing from the outside to the power storage device is set to zero, and the terminals of the power storage device do not necessarily need to be disconnected (opened) from the circuit for measurement.

[0018] In the determination process, the self-discharge state is determined based on the power supply current. Specifically, a method for determining the self-discharge state using the stable power supply current flowing at the time when the power supply current stabilizes, or the time-dependent change in the power supply current until the stable power supply current is reached, can be cited. Examples of methods for determining the self-discharge state using the stable power supply current flowing at the time when the power supply current stabilizes include: obtaining the value of the stable power supply current flowing at the time when the power supply current stabilizes, and then determining whether the self-discharge state is good or bad (OK / NG) based on the value of the stable power supply current and a threshold current value set as a reference; or a method for classifying the self-discharge state into multiple levels such as A / B / C... corresponding to the magnitude of the stable power supply current.

[0019] On the other hand, methods for determining the self-discharge state based on the temporal change in the power supply current until the stable power supply current is reached include, for example, a method in which an estimated stable power supply current value is estimated based on the temporal change in the power supply current until the stable power supply current is reached, and then the self-discharge state is determined to be OK / NG based on the estimated stable power supply current value and the threshold current value; a method in which the self-discharge state is classified into multiple grades such as A / B / C, etc., corresponding to the estimated stable power supply current value; and a method in which the self-discharge state of the power storage device is directly determined and graded based on the amount of change in the power supply current per unit time.

[0020] The detected temporal variation in the power supply current refers to the temporal variation in the power supply current that occurs from the start of the continuous voltage application process until the value of the power supply current flowing through the energy storage device stabilizes. This variation can be expressed, for example, by the amount of increase in the power supply current or the slope of the increase within a predetermined period. Furthermore, at the point in time when a sufficient amount of time has elapsed during the continuous voltage application process, a stable power supply current corresponding to the magnitude of the self-discharge current flowing through the energy storage device flows. This stable power supply current is referred to as the stable power supply current.

[0021] (2) is a method for checking the self-discharge of an electric storage device according to (1), which can be set as the following method for checking the self-discharge of an electric storage device: before the voltage continuous application process, there is also an initial constant current flow process, in which a constant current of a predetermined initial current value is flowed from the external power supply set to a constant current power supply mode to the electric storage device, and the voltage continuous application process following the initial constant current flow process is a process for continuously applying the continuous power supply voltage of a magnitude equal to the initial power supply voltage generated in the external power supply when a constant current of the initial current value is flowed to the electric storage device in the initial constant current flow process.

[0022] In this inspection method, a constant current of the magnitude of the initial current value is passed during the initial constant current flow step. Therefore, during this initial constant current flow step, an initial power supply voltage is generated in the external power supply at a magnitude that is approximately equal to the first device voltage generated in the capacitance component of the energy storage device plus the voltage drop caused by the power supply current of the initial current value flowing through the series resistance (DC resistance) of the energy storage device. Then, in the subsequent continuous voltage application step, a continuous power supply voltage of the same magnitude as the initial power supply voltage is continuously applied. Therefore, at the beginning of this continuous voltage application step, a power supply current equal to the initial current value passed during the initial constant current flow step flows. Thus, in this inspection method, the initial current value passed at the beginning of the continuous voltage application step is fixed for each energy storage device under test, enabling the continuous voltage application step to be started under uniform conditions.

[0023] Furthermore, as described above, when a constant current of the initial current value is passed during the initial constant current passing step, an initial power supply voltage is generated in the external power supply that is approximately equivalent to the sum of the first device voltage generated in the capacitance component of the energy storage device and the voltage drop across the series resistance due to the power supply current of the initial current value. Therefore, this initial power supply voltage is substantially unaffected by the amount of self-discharge current in the energy storage device and remains substantially the same in each energy storage device.

[0024] (3) The method for inspecting the self-discharge of an electric storage device according to (2) can be configured as follows: the initial current value is set to be equal to a threshold current value of the self-discharge current set for the electric storage device.

[0025] In this inspection method, the initial current value is set to be equal to the “threshold current value.” Therefore, at the beginning of the continuous voltage application process, a power supply current of the threshold current value flows through the power storage device.

[0026] Here, (I) if the "self-discharge current of the tested electricity storage device is equal to the threshold current value", the power supply current of the threshold current value continues to flow stably from the beginning of the continuous voltage application step.

[0027] On the other hand, (II) in the case where the "self-discharge current of the tested storage device is greater than the threshold current value", that is, in the case where the tested storage device has unqualified self-discharge characteristics, the magnitude of the power supply current flowing during the continuous voltage application process gradually increases from the threshold current value that initially flows, becomes equal to the self-discharge current that is greater than the threshold current value, and then stabilizes.

[0028] On the other hand, (III) when the "self-discharge current of the tested storage device is less than the threshold current value", that is, when the tested storage device has good self-discharge characteristics, the magnitude of the power supply current flowing during the continuous voltage application process decreases rapidly from the threshold current value that initially flows, becomes equal to the self-discharge current that is less than the threshold current value, and then stabilizes.

[0029] In other words, the direction of change in the power supply current is opposite depending on the quality of the self-discharge characteristics. Therefore, this inspection method makes it possible to easily determine whether the tested energy storage device is a good energy storage device with a self-discharge current less than the threshold current value, or a bad energy storage device with a self-discharge current greater than the threshold current value, by detecting whether the power supply current decreases or increases, or whether it is on a decreasing or increasing trend, from the threshold current value (initial current value) after the start of the continuous voltage application process, without waiting for the power supply current to stabilize. This allows for earlier determination.

[0030] The "threshold current value" refers to a current value used as a reference for determining whether the storage device is good or bad, compared with the current value of the self-discharge current of the storage device charged to the first device voltage, or a current value used as one of multiple reference current values ​​for determining whether the storage device belongs to multiple levels.

[0031] (4) Alternatively, the self-discharge inspection method for an electric storage device according to (1) may be configured as follows: a first device voltage measuring step is provided before the voltage continuous application step, in which the magnitude of the first device voltage of the electric storage device is measured, and the voltage continuous application step following the first device voltage measurement step is a step of continuously applying the continuous power supply voltage of a magnitude obtained by adding a predetermined incremental voltage to the first device voltage.

[0032] In this inspection method, for each energy storage device under inspection, the magnitude of the first device voltage is measured in a first device voltage measurement step. In the subsequent continuous voltage application step, a continuous power supply voltage of a magnitude obtained by adding a predetermined incremental voltage of the same magnitude to the measured first device voltage is continuously applied. Therefore, from the start of the continuous voltage application step, a power supply current corresponding to the applied continuous power supply voltage (the sum of the first device voltage and the incremental voltage) flows through each energy storage device. Furthermore, the power supply current flowing through each energy storage device at the start of the continuous voltage application step is largely unaffected by the amount of self-discharge current and remains substantially constant, corresponding to the magnitude of the first device voltage and series resistance (DC resistance) generated in the capacitive component.

[0033] Furthermore, if the magnitude of the power supply current (I) flowing through the energy storage device at the beginning of the continuous voltage application process due to the continuous application of the power supply voltage is equal to the "self-discharge current" of the energy storage device, a stable power supply current equal to the self-discharge current will continue to flow from the beginning of the continuous voltage application process. In other words, the power supply current is stable from the beginning.

[0034] On the other hand, (II) when the power supply current is "smaller than the self-discharge current of the storage device," the power supply current gradually approaches the self-discharge current of the storage device, and stabilizes after becoming equal to the self-discharge current.

[0035] On the other hand, (III) when the magnitude of the power supply current is "greater than the self-discharge current of the power storage device," the power supply current rapidly decreases to the magnitude of the new self-discharge current and then stabilizes.

[0036] In this inspection method, a continuous power supply voltage, obtained by adding the same incremental voltage to the first device voltage, is applied to each energy storage device under test. This allows the continuous voltage application process to be performed under uniform conditions. Furthermore, this inspection method can be performed without using a constant current mode, or using an external power supply that does not have a constant current mode.

[0037] (5) is a self-discharge inspection method for an electrical storage device according to (4), which can be set as the following self-discharge inspection method for an electrical storage device: the incremental voltage is set to a threshold incremental voltage value of a power supply current equal to a threshold current value of a self-discharge current allowed by the electrical storage device at the beginning of the voltage continuous application process.

[0038] In this inspection method, the voltage increment is set to the magnitude of the aforementioned "threshold voltage increment." Specifically, during the continuous voltage application step, a power supply voltage of a magnitude obtained by adding the "threshold voltage increment" to the measured first device voltage is continuously applied to each energy storage device. Therefore, at the beginning of the continuous voltage application step, a power supply current of the "threshold current value" flows through each energy storage device.

[0039] Here, (I) if the "self-discharge current of the tested electricity storage device is equal to the threshold current value", the power supply current of the threshold current value continues to flow stably from the beginning of the continuous voltage application step.

[0040] On the other hand, (II) if the self-discharge current of the tested energy storage device exceeds the threshold current value, that is, if the tested energy storage device has unacceptable self-discharge characteristics, a power supply current having a threshold current value, which is smaller than the self-discharge current of the energy storage device, is initially applied during the continuous voltage application process. As described above, the power supply current gradually increases from the initial current value, and stabilizes after reaching the self-discharge current exceeding the threshold current value.

[0041] On the other hand, (III) when the self-discharge current of the tested energy storage device is less than the threshold current value, that is, when the tested energy storage device has good self-discharge characteristics, a power supply current having a "threshold current value" greater than the self-discharge current of the energy storage device is supplied at the beginning of the continuous voltage application step. As described above, the portion of the supplied power supply current exceeding the self-discharge current is used to charge the energy storage device (its capacitive component). As the continuous voltage application step progresses, the power supply current rapidly decreases from the initial threshold current value, becomes equal to the self-discharge current less than the threshold current value, and then stabilizes.

[0042] In other words, the direction of change in the power supply current is opposite depending on the quality of the self-discharge characteristics. Therefore, this inspection method makes it possible to easily determine whether the tested energy storage device is a good energy storage device with a self-discharge current less than the threshold current value, or a bad energy storage device with a self-discharge current greater than the threshold current value, by detecting whether the power supply current decreases or increases, or whether it is on a decreasing or increasing trend, from the threshold current value (initial current value) after the start of the continuous voltage application process, without waiting for the power supply current to stabilize. This allows for earlier determination.

[0043] In addition, as described above, the "threshold current value" refers to a current value used as a reference for determining whether the storage device is good or bad by comparison with the current value of the self-discharge current of the storage device charged to the first device voltage, or a current value used as one of multiple reference current values ​​for determining whether it belongs to multiple levels.

[0044] The "threshold incremental voltage" refers to an incremental voltage of a magnitude that causes a power supply current equal to the "threshold current value" to flow when a continuous power supply voltage of a magnitude obtained by adding the "threshold incremental voltage" to the first device voltage is applied from an external power supply to a power storage device charged to a first device voltage.

[0045] (6) Furthermore, another solution is a method for manufacturing an electric storage device, comprising the following steps: an initial charging step of initially charging an assembled uncharged electric storage device to a predetermined charging state, thereby setting it as a pre-charged electric storage device; and an inspection step of inspecting the self-discharge state of the above-mentioned electric storage device that has been initially charged by using the self-discharge inspection method for the electric storage device described in any one of (1) to (5) above.

[0046] In the above-mentioned method for manufacturing an electricity storage device, the inspection step using the above-mentioned self-discharge inspection method is performed after the initial charging step. Therefore, the presence and extent of short circuits in the initial stage of the electricity storage device can be appropriately inspected in a short time and the electricity storage device can be manufactured.

[0047] Furthermore, it is more preferable to provide a high-temperature aging step of leaving the energy storage device at high temperature in an open-circuit state and a subsequent cooling step between the initial charging step and the inspection step because the voltage of the energy storage device is more likely to be stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a longitudinal cross-sectional view of the battery according to the first and second embodiments and the first and second modifications.

[0049] Figure 2 The first embodiment and modifications 1 and 2 are flowcharts of a battery manufacturing process including a process of inspecting the battery for self-discharge.

[0050] Figure 3 This is a circuit diagram of a battery self-discharge inspection method according to the first embodiment and modifications 1 and 2, in a state where an external power source is connected to the battery.

[0051] Figure 4 The graphs schematically show temporal changes of the power supply voltage VS and the power supply current IP with respect to the voltage application time t for each of the batteries of the first embodiment and the reference embodiment and the defective battery.

[0052] Figure 5 Regarding Modification 1 and Reference, the graph schematically shows temporal changes in power supply voltage VS and power supply current IP with respect to voltage application time t for each of acceptable and defective batteries.

[0053] Figure 6 Concerning Modification 2 and the reference embodiment, the graph schematically shows temporal changes in power supply voltage VS and power supply current IP with respect to voltage application time t for each of acceptable and defective batteries.

[0054] Figure 7 The second embodiment is a flowchart of a battery manufacturing process including a process of inspecting the battery for self-discharge.

[0055] Figure 8 This is a circuit diagram of a battery self-discharge inspection method according to a second embodiment, in a state where an external power source is connected to the battery.

[0056] Figure 9 The graphs related to the second embodiment and the reference embodiment schematically show temporal changes in the power supply voltage VS and the power supply current IP with respect to the voltage application time t for each of the conforming and defective batteries.

[0057] (Explanation of Reference Numerals)

[0058] 1: (charged) battery (electricity storage device); S2: initial charging process; S5: placement process; S6: initial constant current flow process (inspection process); S26: initial battery voltage measurement process (first device voltage measurement process, inspection process); S7, S27: continuous voltage application process (inspection process); S8, S28: current detection process (inspection process); S9, S29: continuous judgment process (inspection process); t: voltage application time; S10: judgment process (inspection process); TB: battery temperature (device temperature); TB1: first battery temperature (first device temperature); VB: battery voltage (device voltage); VBso: initial open circuit battery voltage (first open circuit battery voltage) =Device voltage); Vα: differential voltage; EP1, EP2: external power supply; VP: power supply voltage (of the external power supply); ΔVP: incremental voltage; ΔVPth: threshold incremental voltage; VP0: initial power supply voltage value; VPc: continuous power supply voltage; IP: power supply current; IP0: initial current value; IP(n): (acquired) power supply current value; IPs: power supply current at steady state; IPth: threshold current value (of the power supply current); 1B: battery component; VBB: battery component voltage (generated in the battery component); Rs: series resistance (of the battery); Rp: short-circuit resistance (of the battery); ID: self-discharge current; IDth: threshold current value (of the self-discharge current). DETAILED DESCRIPTION

[0059] (Implementation Method 1)

[0060] Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings. Figure 1, a longitudinal cross-sectional view of a lithium-ion secondary battery (hereinafter simply referred to as a "battery") 1 according to the first embodiment is shown. The battery 1 is composed of a rectangular box-shaped battery case 10, a flat wound electrode body 20 and an electrolyte 15 housed in the battery case 10, and a positive terminal member 30 and a negative terminal member 40 supported by the battery case 10. In the first embodiment, a lithium transition metal composite oxide, specifically lithium nickel cobalt manganese oxide, is used as the positive electrode active material, and a carbon material, specifically graphite, is used as the negative electrode active material. The same applies to the battery 1 according to the modified embodiments 1 and 2, the second embodiment, and the reference embodiment described later.

[0061] Next, a self-discharge inspection method for determining the insulation performance of the battery 1 and a method for manufacturing the battery 1 including the method will be described (see Figure 2 First, in the "assembly process" S1, an uncharged battery 1X is assembled (see Figure 1 The initial constant current flow step S6 to the determination step S10 described later also correspond to the inspection step in the method for manufacturing the battery 1 .

[0062] Next, in the "initial charging step" S2, the assembled battery 1X is initially charged to form the battery 1. Specifically, a restraining jig (not shown) is used to tighten the battery in the thickness direction (in the Figure 1 The 10 batteries 1 (batteries 1X) arranged in a row (in a direction perpendicular to the paper) are constrained in a compressed state in the direction of the battery thickness. In this constrained state, the initial charging process S2 to the continuous judgment process S9 described later are performed for each battery 1 (battery 1X). In each process, the ambient temperature TK around the battery 1 is detected using a temperature detection device KTS having a temperature sensor KT composed of a thermistor. In addition, the battery temperature TB of each battery 1 is detected using a temperature detection device STS having a temperature sensor ST in contact with a specified position of the battery box 10 (refer to Figure 3 ).

[0063] After restraining each battery 1X with a restraining fixture, at the initial charging temperature FT (FT = 20°C), the two terminal members 30 and 40 of each battery 1X are connected to a charging and discharging device (not shown), and each battery 1 is initially charged by constant current constant voltage (CCCV) charging until the battery voltage VB of each battery 1X reaches a predetermined value (in this embodiment, VB = 4.0V).

[0064] Next, in the "high-temperature aging step" S3, each initially charged battery 1 is left at an aging temperature ET (ET = 63°C) for an aging period EK (EK = 20 hours) with the two terminal members 30, 40 open. This high-temperature aging causes the battery voltage VB of each battery 1 to decrease, reaching a battery voltage corresponding to approximately 80% SOC.

[0065] Next, in the "cooling step" S4, the battery 1 is placed in a cooling chamber CR at a cooling temperature CT (CT = 20°C) for 20 minutes and forcedly cooled by a fan, thereby setting the battery temperature TB to approximately 20°C (TB ≈ 20°C) (see Figure 2 ).

[0066] Furthermore, in the "standing step" S5, the battery 1 is transferred to the first chamber KR1 where the ambient temperature TK is set to the first ambient temperature TK1 (TK1 = 20.0°C) and is left for a standing period HP (for example, HP = 30 minutes). The battery temperature TB of the battery 1 is set to the first battery temperature TB1 (TB1 = 20.0°C) which is the same as the first ambient temperature TK1 (refer to Figure 2 Then, after the standing step S5 , the initial constant current flowing step S6 to the continuation determination step S9 described later are also performed under the condition that the battery temperature TB of the battery 1 is the first battery temperature TB1 .

[0067] In the subsequent "initial constant current flow step" S6, a constant current (initial current value IP0) ​​is passed to the battery 1 at the first battery temperature TB1 (TB1 = 20.0°C). Specifically, Figure 3 As shown, the battery 1 is connected to the external power supply EP1, and the power supply current IP flowing from the external power supply EP1 to the battery 1 is set to a constant current of an initial current value IP0 (IP=IP0), and the initial power supply voltage value VP0 generated in the external power supply EP1 at this time is measured. More specifically, a pair of probes P1 and P2 of the external power supply EP1 are brought into contact with the positive terminal member 30 and the negative terminal member 40 of the battery 1, respectively. The power supply current IP of the initial current value IP0 is passed from the DC current source EPC of the external power supply EP1, which is set to a constant current power supply mode by switching the switch SW, and the initial power supply voltage value VP0 generated in the external power supply EP1 at this time is measured using a voltmeter EPV (see Figure 3 In the first embodiment, for example, the initial current value IP0 is set to 10 μA. The magnitude of the initial current value IP0 (IP0 = 10 μA) is smaller than the magnitude of the self-discharge current (ID = 15 μA) flowing through a typical non-defective battery 1G.

[0068] Furthermore, (without reconnecting the pair of probes P1 and P2 to the terminal members 30 and 40) the initial constant current flow step S6 to the continuation determination step S9 described later are performed while maintaining the contact state between probe P1 and the positive terminal member 30 and the contact state between probe P2 and the negative terminal member 40 (this also applies to variations 1 and 2). This is to prevent the contact state between probes P1 and P2 and the terminal members 30 and 40 from changing each time they make contact, thereby preventing the magnitude of the contact resistance R12 generated between probe P1 and the positive terminal member 30 and between probe P2 and the negative terminal member 40 from fluctuating.

[0069] exist Figure 3 In the figure, wiring resistance Rw represents the wiring resistance distributed within external power supply EP1 and between external power supply EP1 and probes P1 and P2. Furthermore, contact resistance R12 represents the sum of the contact resistance between one probe P1 of external power supply EP1 and positive terminal member 30 of battery 1, and the contact resistance between the other probe P2 of external power supply EP1 and negative terminal member 40 of battery 1.

[0070] In addition, Figure 3 (and the following Figure 8 ), an equivalent circuit of a battery 1 (qualified battery 1G, unqualified battery 1N, threshold battery 1TH) including a battery component 1B, a series resistor Rs, and a short-circuit resistor Rp is also shown. The battery component 1B is a capacitive component formed by the battery 1, and a battery component voltage VBB is generated. The series resistor Rs is a battery resistor that is considered to exist in series with the battery component 1B between the two terminal members 30 and 40 of the battery 1. On the other hand, the short-circuit resistor Rp is a resistor that indicates the magnitude of self-discharge caused by the internal short circuit of the battery 1. The self-discharge current ID indicated by the dotted arrow represents the self-discharge current flowing from the battery component 1B through the short-circuit resistor Rp.

[0071] In each embodiment and variant, the characteristics of multiple batteries 1 (qualified battery 1G, unqualified battery 1N, threshold battery 1TH) are examined. For ease of examination, it is assumed that only the short-circuit resistance Rp and the self-discharge current ID flowing through the short-circuit resistance Rp are different in each battery 1, and the capacitance and series resistance Rs of the battery component 1B are the same (equal to each other). In addition, the wiring resistance Rw and the contact resistance R12 are also equal. In addition, the initial open-circuit battery voltage VBso, that is, the battery component voltage VBB of the battery component 1B at the beginning (voltage application time t = 0) of the initial constant current flow step S6, the initial battery voltage measurement step S26, and the voltage continuous application step S7 and S27 are also equal to each other between the batteries 1.

[0072] Figure 3The external power supply EP1 used in the first embodiment and variations 1 and 2 shown is a variable constant-voltage and constant-current power supply capable of switching between a constant-voltage power supply mode using a DC voltage source EPE and a constant-current power supply mode using a DC current source EPC using a switch SW. This is a precision DC power supply capable of variably and accurately controlling the power supply voltage VS generated by the DC voltage source EPE and the power supply current IP flowing from the DC current source EPC. This external power supply EP1 includes a voltmeter EPV capable of accurately measuring the power supply voltage VP applied to the battery 1, and an ammeter EPI capable of accurately measuring the power supply current IP flowing from the external power supply EP1 to the battery 1. The ambient temperature TK surrounding the battery 1 is detected by a temperature detection device KTS comprising a temperature sensor KT formed by a thermistor. Furthermore, the battery temperature TB of the battery 1 is detected by a temperature detection device STS comprising a temperature sensor ST formed by a thermistor.

[0073] As described above, in the first embodiment, in the initial constant current flow step S6, after the external power supply EP1 is connected to the battery 1 at the first ambient temperature TK1 and the first battery temperature TB1 is equal to the first ambient temperature TK1 (TB1 = TK1 = 20.0°C), a power supply current IP having an initial current value IP0 (IP = IP0 = 10 μA) is supplied. This causes the power supply current IP to flow through the battery 1 along the path indicated by the dashed arrow, generating an initial battery voltage VB0 corresponding to the initial current value IP0 in the battery 1. This initial battery voltage VB0 is the battery voltage obtained under the condition that the initial current value IP0 flows, and therefore is slightly (e.g., approximately several to several tens of μV) higher than the initial open-circuit battery voltage VBso, which is the open-circuit voltage of the battery 1 (assuming the battery voltage when the power supply current IP = 0) (VB0 > VBso). Furthermore, the initial power supply voltage VP0 generated in the external power supply EP1 is measured using a voltmeter EPV, including the voltage drop caused by the initial current IP0 flowing through the contact resistance R12 and the wiring resistance Rw. This initial power supply voltage VP0 is measured to be approximately 3.9V, slightly (e.g., approximately several tens of μV) greater than the initial battery voltage VB0 (VP0 > VB0 > VBso). This initial constant current flow step S6 is performed to obtain the value of the initial power supply voltage VP0, and therefore can be completed quickly (e.g., within a few seconds) upon obtaining the value of the initial power supply voltage VP0.

[0074] Further, the battery component voltage VBB coincides with the battery voltage VB in the case where the power supply current IP is zero (IP = 0). Thus, at the start time point of the initial constant current flow process S6 and the following voltage continuous application process S7 (time point of voltage application time t = 0), the battery component voltage VBB is equal to the initial open circuit battery voltage VBso (VBB = VBso, t = 0).

[0075] Next, in the "voltage continuous application process" S7, at the first ambient temperature TK1, in a state where the first battery temperature TB1 becomes equal to the first ambient temperature TK1, the switch SW is switched to be set to the constant voltage power supply mode, the direct current voltage source EPE of the external power supply EP1 is caused to generate a continuous power supply voltage VPc (VPc = VP0) equal to the initial power supply voltage value VP0 (slightly larger than the initial open circuit battery voltage VBso) obtained in the aforementioned initial constant current flow process S6, the application of the continuous power supply voltage VPc to the battery 1 is started (voltage application time t = 0), and thereafter the application of the continuous power supply voltage VPc is continuously performed. That is, the continuous power supply voltage VPc generated in the external power supply EP1 is maintained to be equal to the initial power supply voltage value VP0 obtained at the beginning. Therefore, unlike the conventional technique in which the power supply current does not flow (IP(0) = 0) at the beginning because of VPc = VBso, the power supply current IP flows in the battery 1 from the beginning of the voltage continuous application process S7.

[0076] In the "current detection process" S8, the power supply current IP is detected with the current meter EPI. That is, the power supply current value IP(n) (n is an integer of 0 or more indicating the order of acquisition) of the power supply current IP flowing from the external power supply EP1 to the battery 1 is obtained every prescribed time (10 seconds in the present embodiment). Further, the power supply current value IP(0) of the power supply current IP at the beginning of the application of the continuous power supply voltage VPc (voltage application time t = 0) becomes equal to the initial current value IP0 flowing in the initial constant current flow process S6 (IP(0) = IP0). However, as will be described later, in the present embodiment 1, the power supply current IP (power supply current value IP(n)) changes as the voltage application time t elapses, approaches the magnitude of the inherent self-discharge current ID which differs for each battery 1, and becomes stable when the power supply current IP becomes equal to the self-discharge current ID.

[0077] In the "continuation determination step" S9, a determination is made as to whether the continuous voltage application step S7 and the current detection step S8 should be repeated. In this first embodiment, a determination is made as to whether the power supply current IP (specifically, the power supply current value IP(n)) has stabilized after the start of continuous application of the power supply voltage VPc to the battery 1. If the result is "No," meaning that the power supply current IP has not stabilized, the process returns to the continuous voltage application step S7, where the continuous application of the power supply voltage VPc to the battery 1 continues (S7), and the power supply current IP is detected again (S8). On the other hand, if the result is "Yes," meaning that the power supply current IP has stabilized, the process proceeds to the "determination step" S10, described below.

[0078] In addition, in the continuous judgment process S9, as a method for judging whether the power supply current IP has stabilized, for example, the following method can be cited: in the continuous judgment process S9, the moving average value of the power supply current value IP(n) is calculated successively (for example, the moving average value of the 7 power supply current values ​​IP(n-6) to IP(n) obtained in the most recent 60 seconds), and whether the power supply current value IP(n) has stabilized is judged based on the progress of the moving average value (for example, the difference value of the moving average value, the size of the differential value).

[0079] In the voltage continuous application step S7 of the first embodiment, as described above, a continuous power supply voltage VPc equal to the initial power supply voltage value VP0 is continuously applied to the battery 1 while the ambient temperature TK is maintained at the first ambient temperature TK1 and the battery temperature TB is maintained at the first battery temperature TB1 (TB1 = TK1 = 20.0°C). The following discusses how the power supply current value IP(n) of the power supply current IP flowing from the external power supply EP1 to the battery 1 changes in this situation.

[0080] Furthermore, as described above, at the voltage application time t=0, the battery component voltage VBB is equal to the initial open-circuit battery voltage VBso (VBB=VBso, t=0).

[0081] (Reference method)

[0082] Here, first, as a reference, the method described in Patent Document 1, Figure 4 As shown by the thin solid line in the upper part of FIG, the power supply current IP changes when the initial open-circuit battery voltage VBso is continuously applied from the external power supply EP1 to the battery 1 after the voltage application starts (t=0). Figure 3 、 Figure 4 to discuss.

[0083] When the initial open-circuit battery voltage Vbso is continuously applied to the battery 1 from the external power supply EP1, the battery component voltage VBB of the battery component IB gradually decreases from the initial open-circuit battery voltage Vbso at the start of the voltage application process S7 (at the time point of the voltage application time t = 0) as the voltage application time t elapses. This is because the electric charge accumulated in the battery component IB is gradually discharged through the self-discharge current ID via the short-circuit resistance Rp.

[0084] Therefore, at the initial application of the initial open-circuit battery voltage Vbso (at the voltage application time t = 0), the power supply current IP does not flow (IP(0) = 0), but as the battery component voltage VBB generated in the battery component IB decreases, the power supply current IP gradually increases as indicated by the arrow with a double-dot chain line according to Figure 3 As can be easily understood, a potential difference (Vbso - VBB) is generated across the series resistance of the three of the series resistance Rs, the contact resistance R12, and the wiring resistance Rw, and the power supply current IP corresponding thereto flows through the battery 1 in the path indicated by the arrow with a double-dot chain line (Vbso = VBB + (Rs + R12 + Rw) • IP).

[0085] Furthermore, as indicated by the lower part of the thick solid line or the thin dotted line in Figure 4 , the magnitude of the power supply current IP of this reference method gradually increases as the battery component voltage VBB of the battery component IB decreases. However, as can be understood from Figure 3 , as the battery component voltage VBB decreases, the power supply current IP increases, and when the counter electromotive force Vp (Vp = Rp • IP) generated in the short-circuit resistance Rp due to the power supply current IP flowing therein becomes equal to the battery component voltage VBB generated in the battery component IB, the self-discharge current ID no longer flows out of the battery component IB. Thus, the decrease in the battery component voltage VBB in the battery component IB also stops, and the power supply current IP becomes stable after the stable time power supply current Ips.

[0086] Thus, if the battery 1 under test is a good product battery (a battery in which the short-circuit resistance Rp is large and the self-discharge current ID is smaller than the threshold current value Idth) 1G, the battery component voltage VBB of the battery component IB slowly decreases, and therefore the power supply current IP also slowly increases (refer to the thin solid line of the lower part of Figure 4 ). In addition, the stable time power supply current value IPsg of this good product battery 1G is small (for example, assuming IPsg = 15 μA as a value of a typical good product battery 1G).

[0087] On the other hand, when the test battery 1 is a defective battery (a battery having a smaller short-circuit resistance Rp and a self-discharge current ID than the qualified battery 1G) 1N, the battery component voltage VBB of the battery component 1B is relatively significantly lower than that of the qualified battery 1G, and the power supply current IP is also relatively significantly increased (refer to Figure 4 The steady-state power supply current value IPsn of the defective battery 1N is also greater than the steady-state power supply current value IPsg of the conforming battery 1G (for example, as a typical value of the defective battery 1N, IPsn = 27 μA > IPsg is assumed).

[0088] Therefore, the quality of the battery 1 under test can be determined based on the magnitude of the power supply current value IPs (IPsg, IPsn) when stable, or based on the magnitude and change of the speed of increase of the power supply current IP (time-dependent change of the power supply current IP) (see Patent Document 1). Figure 4 In the lower graph of FIG, the threshold current value IPth of the power supply current IP (equal to the threshold current value IDth of the self-discharge current ID) is shown in FIG. Figure 4 As indicated by the thin solid line in FIG, the value determined is the middle value between the steady-state power supply current value Ipsg of the acceptable battery 1G and the steady-state power supply current value IPsn of the defective battery 1N (for example, IPth = 20 μA). Thus, by comparing the obtained steady-state power supply current value IPs (IPsg, IPsn) with the threshold current value IPth, it is possible to determine whether the battery 1 is acceptable.

[0089] However, in this reference method, it takes time from the start of continuous application of the power supply voltage VPc to the battery 1 (t=0) until the battery 1 can be judged to be good or bad. This is because the power supply current IP gradually increases to reach the stable power supply current IPs in order to compensate for the drop in the battery component voltage VBB caused by the discharge of the charge of the capacitive component 1B of the battery 1 through the short-circuit resistor Rp. For example, when making a judgment based on the value of the stable power supply current IPs, it is necessary to wait until the stable power supply current IPs value is obtained. For example, Figure 4 As can be seen from the above example represented by the thin solid line and the dotted line in the lower graph of , in order to obtain the value of the power supply current IPs (IPsg, IPsn) in a stable state, it is necessary to wait for the voltage application time t to pass for more than 55 minutes.

[0090] This is because it takes time until the battery 1 can be judged to be good or not. Figure 4The lower graph can be understood as follows. In the method of the above-described reference manner (Patent Document 1), in the voltage constant application process S7, the initial open-circuit cell voltage VBso is constantly applied from the state where the power supply current value IP(0) of the power supply current IP at the start of the initial voltage application time t = 0 is zero (IP(0) = 0), and thus it takes time until the power supply current value IP(n) reaches the steady state.

[0091] Therefore, in the present embodiment 1, as in Figure 4 In the lower graph, as indicated by the thick solid line and the broken line, for each of the batteries 1 under test, the power supply current IP of the same magnitude as the initial current value IP0 (IP(0) = IP0) is caused to flow from the start time point of the voltage constant application process S7 (voltage application time t = 0). Thus, in the present embodiment 1, compared with the reference manner, the time until the power supply current IP(n) acquired in the current detection process S8 reaches the steady state is shortened.

[0092] Here, consider the case where the batteries 1 under test are the qualified product batteries 1G. In this case, in the initial constant current flow process S6, when the power supply current IP of the initial current value IP0 (for example, IP0 = 10 μA) is caused to flow, the power supply voltage VP of the magnitude of the initial power supply voltage value VP0 is generated in the external power supply EP1. Further, since the power supply current IP of the initial current value IP0 is caused to flow, the initial power supply voltage value VP0 becomes a value that is slightly higher (by the amount of the difference voltage Vα) than that indicated in the reference manner shown by the thin solid line. Then, in the voltage constant application process S7, as indicated by the thick solid line in the upper graph of Figure 4 the power supply voltage VPc of the same magnitude as the initial power supply voltage value VP0 is constantly applied. Thus, as indicated by the thick solid line in the lower graph of Figure 4 the power supply current IP of the same magnitude as the initial current value IP0 (IP(0) = IP0) flows at the initial (voltage application time t = 0) of the voltage constant application process S7. Thereafter, the power supply current IP gradually increases to stabilize at the steady state of the qualified product battery 1G at the steady state power supply current value IPsgα that is slightly higher (by the amount corresponding to the difference voltage Vα) than the steady state power supply current value Ipsg of the qualified product battery 1G in the case of the reference manner. Here, as can be easily understood by comparing with the case of the reference manner indicated by the thin solid line, it is known from the comparison between the qualified product batteries 1G that, according to the method of the present embodiment 1, compared with the method of the reference manner, the time taken until the power supply current IP stabilizes can be greatly shortened.

[0093] Next, consider the case where the battery 1 to be tested is an unqualified battery 1N. In this case, also in the initial constant current flow step S6, when the power supply current IP of the initial current value IP0 (for example, IP0 = 10μA) flows, a power supply voltage VP of the magnitude of the initial power supply voltage value VP0 is generated in the external power supply EP1. In addition, whether the battery 1 is an unqualified battery 1N or a qualified battery 1G (mentioned above), the magnitude of the initial power supply voltage value VP0 is almost the same. This is because the initial power supply voltage value VP0 is approximately the value obtained by adding the voltage drop caused by the power supply current IP of the initial current value IP0 flowing through the series resistance of the three series resistances, the series resistance Rs, the contact resistance R12, and the wiring resistance Rw to the open circuit voltage of the battery 1 (initial open circuit battery voltage VBso). Then, in the voltage continuous application step S7, a continuous power supply voltage VPc of the magnitude equal to the initial power supply voltage value VP0 is continuously applied. Thus, as in Figure 4 As shown by the thick dashed line in the lower graph of . That is, at the beginning of the voltage continuous application step S7 (voltage application time t = 0), a power supply current IP of the same magnitude as the initial current value IP0 (IP(0) = IP0) ​​flows, similarly to the qualified battery 1G. However, thereafter, the power supply current IP gradually increases, but increases significantly compared to the qualified battery 1G, and stabilizes at a stable power supply current value IPsnα that is slightly higher than the stable power supply current value IPsn of the defective battery 1N in the reference method. Here, as can be easily understood by comparing with the case of the reference method shown by the thin dashed line, it can be seen that even when comparing between the defective batteries 1N, according to the method of this embodiment 1, the time taken until the power supply current IP stabilizes can be significantly shortened compared to the method of the reference method.

[0094] As can be seen, in the first embodiment, regardless of whether the battery 1 is a conforming battery 1G or a defective battery 1N, the self-discharge state of the battery 1 can be determined earlier in the determination step S10 than in the reference method.

[0095] In addition, in the "determination process" S10, the self-discharge state of the battery 1 is determined based on the obtained power supply current IP, specifically using the arrangement of the power supply current values ​​IP(0), IP(1), ..., IP(n) obtained after the start of the voltage continuous application process S7 (voltage application time t=0).

[0096] In the present embodiment 1, specifically, 7 power supply current values IP(n-6) to IP(n) obtained at the end of the voltage-continuously-applied process S7 (in the present embodiment, in the last 60 seconds) among a series of power supply current values IP(0), IP(l),..., IP(n) obtained at prescribed time intervals (in the present embodiment, every 10 seconds) are averaged to calculate an average end-period power supply current value IPE (IPE = (IP(n-6) +... + IP(n)) / 7). The average end-period power supply current value IPE indicates the magnitude of the steady-state power supply current IPs at the end of the voltage-continuously-applied process S7. This is compared with the threshold current value IPth, and the battery 1 for which the average end-period power supply current value IPE is less than the threshold current value IPth (IPE < IPth) is determined to be a good battery 1G. In this way, a battery 1 (good battery 1G) for which the self-discharge state is checked after charging can be manufactured.

[0097] On the other hand, the battery 1 for which the average end-period power supply current value IPE is equal to or greater than the threshold current value IPth (IPE > IPth) is determined to be a non-good battery 1N. The battery 1 determined to be a non-good battery 1N is excluded and discarded. Alternatively, it is recycled by being disassembled and the like.

[0098] In the above-described embodiment 1, in the determination process S10, the plurality of power supply current values IP(n) and the like obtained at the end are averaged to calculate the average end-period power supply current value IPE corresponding to the value of the steady-state power supply current IPs, and this is compared with the threshold current value IPth to determine whether the battery 1 is good or not.

[0099] However, the last-obtained moving average value MIP(n) among the plurality of (for example, 7) power supply current values IP(n-6) to IP(n) obtained at the end in the continuous determination process S9 can be used as the above-described average end-period power supply current value IPE to determine the self-discharge state of the battery 1 in the determination process S10. That is, in the determination process S10, the last-obtained moving average value MIP(n) in the continuous determination process S9 can be compared with the threshold current value IPth to determine whether the battery 1 is good or not.

[0100] As described above, in the method of the present embodiment 1, the power supply current IP flowing through the battery 1 under test can be made to stabilize earlier than in the conventional checking method, and the self-discharge check of the checking processes S6 to S10 can be performed earlier.

[0101] Furthermore, in the manufacturing method of the battery 1 of the first embodiment, after the initial charging step S2, the inspection steps S6 to S10 using the self-discharge inspection method are performed. Therefore, the presence and extent of short circuits in the initial stage of the battery 1 can be appropriately inspected in a short time and the battery 1 can be manufactured.

[0102] In addition, in the inspection method of the present embodiment 1, for each battery 1 to be tested, the initial current value IP0 flowing at the beginning of the voltage continuous application step S7 is determined to be fixed (in the present embodiment 1, for example, IP0 = 10 μA), so that the voltage continuous application step S7 can be started under uniform conditions.

[0103] (Deformation method 1)

[0104] In the above-mentioned embodiment 1 (refer to Figure 4 ), in the initial constant current flow step S6, the magnitude of the power supply current IP flowing to the battery 1 (initial current value IP0) ​​is set to, for example, IP0 = 10 μA, so as to be smaller than the threshold current value IPth (IPth = 20 μA). Furthermore, the initial current value IP0 is set to be smaller than the typical steady-state power supply current value IPsgα of the qualified battery 1G (as a typical value, IPsgα = 15 μA is assumed). However, the magnitude of the power supply current IP flowing to the battery 1 in the initial constant current flow step S6 (initial current value IP0) ​​may be set to be equal to the threshold current value IPth (variation 1). Alternatively, it may be set to be larger than the current value IPth (variation 2).

[0105] Therefore, in this modification 1, the main reference Figure 3 、 Figure 5 The following case is described: although the method is the same as that of the first embodiment, the initial current value IP0 of the power supply current IP flowing to the battery 1 in the initial constant current flowing step S6 is made equal to the threshold current value IPth (for example, IP0 = IPth = 20 μA).

[0106] First, the characteristics of the qualified battery 1G, the unqualified battery 1N, and the threshold battery 1TH in the initial constant current flow process S6 and the voltage continuous application process S7 are discussed. In addition, the "threshold battery" 1TH refers to a battery 1 in which the self-discharge current ID flowing in the short-circuit resistance Rp is equal to its threshold current value IDth (= IPth) when charged to the initial open-circuit battery voltage VBso (for example, 3.9V), that is, when the battery component voltage VBB of the battery component 1B is set to the initial open-circuit battery voltage VBso (in this variant 1, ID=IDth=IPth=20μA). On the other hand, the "qualified battery" 1G refers to a battery 1 in which the short-circuit resistance Rp is larger than that of the threshold battery 1TH, and the self-discharge current ID is smaller (IDth) when charged to the same initial open-circuit battery voltage VBso. <IPth)的电池。另一方面,“不合格电池”1N是指,与阈值电池1TH相比短路电阻Rp小、且在充电至相同的初始开路电池电压VBso的状态下自放电电流ID大(ID> IPth) of the battery.

[0107] When a power supply current IP having an initial current value IP0 (=threshold current value IPth=20μA) is supplied to the battery 1 in the initial constant current supply step S6, a power supply voltage VP having an initial power supply voltage value VP0 is generated in the external power supply EP1. Furthermore, the magnitude of the initial power supply voltage VP0 is substantially the same regardless of whether the battery 1 is a qualified battery 1G or a defective battery 1N, as described in the first embodiment. Therefore, for any battery 1, the voltage is continuously applied in the step S7 as in the example shown in FIG. Figure 5 As shown by the thick solid line in the upper graph of , a continuous power supply voltage VPc equal to the initial power supply voltage value VP0 is continuously applied. In addition, the power supply current value IP(0) flowing at the beginning of the voltage continuous application step S7 becomes a threshold current value IPth equal to the threshold current value IDth of the self-discharge current ID of the threshold battery 1TH. Therefore, if the battery 1 under test is a threshold battery 1TH, then as in Figure 5 As indicated by the thick single-dot chain line in the lower graph of , the power supply current IP is stable from the beginning, and remains equal to the threshold current value IPth even after the voltage application time t has passed.

[0108] On the other hand, in the case where the battery 1 to be tested is a non-conforming battery 1N, as in Figure 5As shown by the thick dashed line in the lower graph of , at the beginning of the voltage application step S7 (voltage application time t=0), similar to the threshold battery 1TH, a power supply current IP (IP(0)) having a threshold current value IPth flows. However, thereafter, the power supply current IP gradually increases and stabilizes at a stable power supply current value IPsnα that is slightly higher (by an amount corresponding to the difference voltage Vα) than the stable power supply current value IPsn of the defective battery 1N in the reference mode shown by the thin dashed line.

[0109] On the other hand, if the battery 1 to be tested is a qualified battery 1G, Figure 5 As indicated by the thick solid line in the lower graph, at the beginning of the voltage application step S7 (voltage application time t = 0), a power supply current IP (IP(0)) having a threshold current value IPth flows, similarly to the threshold battery 1TH and the defective battery 1N. However, thereafter, the power supply current IP decreases rapidly and stabilizes at a stable power supply current value IPsgα, which is slightly higher than the stable power supply current value IPsg of the good battery 1G in the reference system.

[0110] In this variant 1, the power supply current IP flowing through the qualified battery 1G decreases sharply at the beginning of the continuous voltage application step S7 for the following reason. As previously mentioned, the qualified battery 1G has a larger short-circuit resistance Rp and a smaller self-discharge current ID than the threshold battery 1TH. Therefore, the stable power supply current value IPsgα is also smaller than the stable power supply current value IPsthα (=threshold current value IPth) of the threshold battery 1TH. Therefore, if a power supply current IP of the magnitude of the threshold current value IPth is intended to flow at the beginning of the continuous voltage application step S7, a portion of the power supply current IP flowing through the qualified battery 1G does not flow through the short-circuit resistance Rp but flows into the battery component 1B and charges it. In addition, the series resistance of the three components, namely the series resistance Rs, the contact resistance R12, and the wiring resistance Rw, is sufficiently low compared to the short-circuit resistance Rp. Therefore, the battery component 1B is quickly charged and the battery component voltage VBB rises. As a result, the power supply current IP flowing from the external power supply EP1 decreases sharply. However, since a slightly increased self-discharge current ID flows in accordance with the rising battery component voltage VBB, the power supply current IP stabilizes when it decreases to a value equal to the stable power supply current value IPsgα corresponding to the increased self-discharge current ID.

[0111] That is, the direction of change of the power supply current IP after the start of the voltage continuous application step S7 is opposite between the qualified battery 1G and the unqualified battery 1N. Thus, in the present variation 1, the power supply current value IP(n) obtained after the start of the voltage continuous application step S7 (voltage application time t=0) can also be used in the "determination step" S10 to determine the self-discharge state of the battery 1. Specifically, if Figure 5 As can be easily understood by comparing the thick solid line and the thick dotted line in the lower graph of , after the start of the voltage continuous application process S7, the voltage application time t is judged in the continuous judgment process S9 whether it has passed the prescribed time (for example, t = 5 minutes). If the prescribed time has passed ("yes"), it is transferred to the judgment process S10. In the judgment process S10, the power supply current value IP (n) is used to judge the direction of change of the power supply current IP over a period of about several minutes. Then, the battery 1 whose power supply current IP, which was initially the threshold current value IPth, decreases as the voltage application time t passes is judged as a qualified battery 1G. On the other hand, the battery 1 that has not been judged as a qualified battery 1G because it increases after the voltage application time t has passed is judged as a defective battery 1N. Therefore, according to the method of this variant 1, the quality of the battery 1 can be judged extremely early compared not only to the previous method but also to the embodiment 1.

[0112] Other determination methods can also be used. Specifically, in determination step S10, using the power supply current value IP(n), a battery 1 is determined as a qualified battery 1G if the average value of the power supply current value IP(n) from the start of the voltage continuous application step S7 to the time point when the specified voltage application time t has elapsed (e.g., t = 5 minutes), or the average value of the power supply current value IP(n) during a specified period (e.g., t = 4-5 minutes) is less than a threshold current value IPth. Alternatively, a battery 1 that is not determined to be a qualified battery 1G, such as one whose average power supply current value IP(n) is greater than the threshold current value IPth, can be determined as a defective battery 1N. In this case, the quality of the battery 1 can be determined much earlier than in embodiment 1.

[0113] Alternatively, similarly to the first embodiment, in the continuity judgment step S9, a moving average value of the power supply current value IP(n) is used to judge whether the power supply current value IP(n) has stabilized. If the result of the continuity judgment step S9 is "yes" and the process moves to the judgment step S10, the average final power supply current value IPE is calculated in the judgment step S10, and the average final power supply current value IPE is compared with the threshold current value IPth. If the average final power supply current value IPE is less than the threshold current value IPth (IPE), the power supply current value IP(n) is stabilized. <IPth)的电池1判定为合格品电池1G。在该情况下,也与实施方式1相比,能够极其提前地判断电池1的良好与否。

[0114] According to the inspection method of this first variation, the trend of change in power supply current IP is opposite depending on whether the battery 1 is a conforming battery 1G or a defective battery 1N. Thus, even without waiting for the power supply current IP to stabilize, it is possible to easily determine whether the test battery 1 is a conforming battery 1G or a defective battery 1N, whose self-discharge current ID is less than the threshold current value IPth (=IDth), by detecting whether the power supply current IP decreases or increases, or whether it is on a decreasing or increasing trend, from the threshold current value IPth after the start of the continuous voltage application step S7. This allows for a more rapid determination.

[0115] (Deformation method 2)

[0116] In this second variant, although the method is the same as that of the first embodiment and the first variant, the initial current value IP0 of the power supply current IP flowing to the battery 1 in the initial constant current flow step S6 is made greater than the threshold current value IPth (for example, IP0 = 35 μA > IPth = 20 μA). In this variant, the initial current value IP0 is further made greater than the typical steady-state power supply current value IPsnα of the defective battery 1N (for example, as a typical value, IPsnα = 27 μA) (IP0 = 35 μA > IPsnα = 27 μA). For this second variant, refer mainly to Figure 3 、 Figure 6 To explain.

[0117] Here, the characteristics of the conforming battery 1G and the defective battery 1N in the initial constant current flow step S6 and the voltage continuous application step S7 are examined.

[0118] When the battery 1 to be tested is a qualified battery 1G, the characteristics are similar to those of the case of variant 1. That is, when the power supply current IP of the initial current value IP0 (=35μA) is passed in the initial constant current passing step S6, the initial power supply voltage value VP0 is generated in the external power supply EP1. Therefore, in the voltage continuous application step S7, as in Figure 6the upper graph of FIG. 6, a constant power voltage Vpc of the same magnitude as the initial power voltage value Vpo is continuously applied. Thus, as indicated by a thick solid line in the lower graph of FIG. 6, at the beginning of the voltage constant application process S7 (voltage application time t = 0), a power current IP of a large initial current value IP0 flows, but thereafter, the power current IP rapidly decreases to a steady power current value IPsgαstabilized which is slightly lower than the steady power current value IPsg of the good battery 1G in the reference mode. Figure 6

[0119] On the other hand, in the case where the battery 1 under test is the non-good battery IN, the power current IP also rapidly decreases at the initial stage of the voltage constant application process S7, as in the case where the battery 1 is the good battery 1G. That is, when the power current IP of the initial current value IP0 (= 37 μA) is caused to flow in the initial constant current flow process S6, a power voltage VP of the magnitude of the initial power voltage value Vpo is also generated in the external power source EPl. In the voltage constant application process S7, a constant power voltage Vpc of the magnitude of the initial power voltage value Vpo is continuously applied. Thus, as indicated by a thick dashed line in the lower graph of FIG. 6, at the beginning of the voltage constant application process S7 (voltage application time t = 0), a power current IP of a large initial current value IP0 flows, but thereafter, the power current IP rapidly decreases to a steady power current value IPsnαstabilized which is slightly higher than the steady power current value IPsn of the non-good battery IN in the reference mode. Figure 6

[0120] Further, the reason why the power current IP flowing in the good battery 1G and the non-good battery IN at the initial stage of the voltage constant application process S7 of the present modification 2 rapidly decreases is the same as the reason for the characteristics of the good battery 1G explained in the modification 1, and thus the explanation is omitted.

[0121] ​​Thus, in the second modification, the power supply current value IP(n) obtained after the start of the voltage continuous application step S7 (voltage application time t=0) can also be used in the "determination step" S10 to determine the self-discharge state of the battery 1 earlier than in the conventional method. Specifically, as in the first embodiment, in the continuous determination step S9, a moving average value of the power supply current value IP(n) can be used to determine whether the power supply current value IP(n) has stabilized. After the result of "yes" in the continuous determination step S9 and the transition to the determination step S10 is made, the average final power supply current value IPE is calculated in the determination step S10, and the average final power supply current value IPE is compared with the threshold current value IPth. If the average final power supply current value IPE is less than the threshold current value IPth (IPE), the power supply current value IP(n) can be determined earlier. <IPth)的电池1判定为合格品电池1G。于是,在本变形方式2中,与实施方式1相比,也能够极其提前地判断电池1的良好与否。

[0122] In the inspection method of this second variant, the initial current value IP0 is set to a value greater than the threshold current value IPth, that is, greater than the threshold current value IDth (= IPth) of the self-discharge current ID set for the battery 1 (IP0>IPth=IDth). Figure 6 As can be easily understood from the description, for batteries 1 whose stable power supply current IPs (IPsg, IPsn) is less than the initial current value IP0, i.e., for good batteries 1G and defective batteries 1N whose stable power supply current IPsn is less than the initial current value IP0, after the start of the continuous voltage application step S7, the power supply current IP rapidly decreases from the initial current value IP0, reaching the stable power supply current IPs (IPsg, IPsn) of battery 1, and then stabilizes. Therefore, the quality of battery 1 can be determined early. By setting the initial current value IP0 to a value greater than the threshold current value IDth (=IPth) of the self-discharge current ID, the power supply current IP of each battery 1 stabilizes in a very short time, except for the defective battery 1N whose stable power supply current IPsn is greater than the initial current value IP0, allowing the quality of the battery 1 to be determined early in the determination step S10.

[0123] Furthermore, in this second variation, the initial current value IP0 is set to a value greater than the typical steady-state power supply current value IPsnα of the defective battery 1N (IP0>IPsnα). By setting the initial current value IP0 to a value greater than the typical steady-state power supply current value IPsnα of the defective battery 1N, the power supply current IP of each battery 1 is stabilized in a very short time, except for the defective battery 1N having a larger steady-state power supply current value IPsn than the typical defective battery. This allows for early determination of the quality of the battery 1 in the determination step S10.

[0124] (Implementation Method 2)

[0125] In the above-mentioned embodiment 1 and variations 1 and 2 (see Figures 1 to 6 ), before the voltage continuous application step S7, an initial constant current flow step S6 is provided in advance in which a constant current IP of a predetermined initial current value IP0 is passed from an external power supply EP1 set to a constant current power supply mode by a switch SW to the battery 1. In the subsequent voltage continuous application step S7, a continuous power supply voltage VPc of a magnitude equal to the initial power supply voltage VP0 generated in the external power supply EP1 when the power supply current IP of the initial current value IP0 is passed to the battery 1 in the initial constant current flow step S6 is continuously applied. Thus, for any battery 1 having a different self-discharge current ID, such as a qualified battery 1G or a defective battery 1N, the power supply current value IP(0) of the power supply current IP becomes the same initial current value IP0 (IP(0)=IP0) at the beginning of the voltage continuous application step S7 (voltage application time t=0).

[0126] On the other hand, in the present embodiment 2 (refer to Figure 1 、 Figure 2 、 Figures 7 to 9 ) differs in that an initial battery voltage measuring step S26 for measuring the magnitude of the initial open-circuit battery voltage VBso of the battery 1 is provided before the voltage continuous application step S27. In the subsequent voltage continuous application step S27, a continuous power supply voltage VPc of a magnitude obtained by adding a predetermined incremental voltage ΔVP of the same magnitude to the initial open-circuit battery voltage VBso is continuously applied. Therefore, the description will focus on the differences, and the description of the same parts will be omitted or simplified.

[0127] The battery 1 used in the second embodiment is the same as the battery 1 used in the first embodiment and the like, and therefore its description is omitted. Figure 7 ) The assembly process S1 to the placement process S5 are the same as those in the first embodiment, so the description is omitted.

[0128] In the second embodiment, in the "initial battery voltage measurement step" S26 following the standing step S5, the initial open-circuit battery voltage VBso, which is the open-circuit voltage of the battery 1 set to the first battery temperature TB1 (TB1 = 20.0°C), is measured. Specifically, Figure 8 As shown, the external power supply EP2 is connected to the battery 1 by bringing a pair of probes P1 and P2 into contact with the positive terminal member 30 and the negative terminal member 40 of the battery 1, respectively. The power supply current IP flowing from the external power supply EP2 to the battery 1 is set to zero (IP=0), and the initial open-circuit battery voltage VBso of the battery 1 is measured using a voltmeter EPV (refer to Figure 8 In the second embodiment, for ease of consideration, as described above, the initial open-circuit battery voltages VBso of the batteries 1 are assumed to be equal to each other.

[0129] exist Figure 8 The external power supply EP2 used in the second embodiment shown is a precision DC power supply that can variably and accurately control the power supply voltage VS generated by the DC voltage source EPE. It also has a voltmeter EPV and an ammeter EPI, but unlike the external power supply EP1 used in the first embodiment, it is a variable constant voltage power supply that does not have a DC constant current source EPC and a switch SW.

[0130] However, as in the first embodiment, the ambient temperature TK surrounding the battery 1 is detected using the temperature detection device KTS having the temperature sensor KT. Furthermore, the battery temperature TB of the battery 1 is detected using the temperature detection device STS having the temperature sensor ST. Furthermore, in the second embodiment, the connection between the probe P1 and the positive electrode terminal member 30 and the contact between the probe P2 and the negative electrode terminal member 40 are maintained while the initial battery voltage measurement step S26, the voltage continuous application step S27, the current detection step S28, and the continuation determination step S29 (described later) are performed.

[0131] The battery component voltage VBB is identical to the battery voltage VB when the power supply current IP is zero (IP=0). In the initial battery voltage measurement step S26, only the initial open-circuit battery voltage VBso is measured. Therefore, at the beginning of the subsequent "continuous voltage application step" S27 (voltage application time t=0), the battery component voltage VBB generated by the battery component 1B is equal to the initial open-circuit battery voltage VBso (VBB=VBso, t=0).

[0132] In the "voltage continuous application process" S27, at the first ambient temperature TK1, as shown in FIG. Figure 9As shown in the upper graph, the DC voltage source EPE of the external power supply EP2 generates a continuous power supply voltage VPc (VPc = VBso + ΔVP) of a magnitude obtained by adding a predetermined incremental voltage ΔVP to the initial open-circuit battery voltage VBso obtained in the initial battery voltage measurement step S26. Application of this voltage to the battery 1 at the first battery temperature TB1 begins (voltage application time t = 0). Thereafter, application of the continuous power supply voltage VPc continues. In other words, the continuous power supply voltage VPc generated by the external power supply EP2 is maintained at a constant magnitude. Therefore, unlike conventional techniques in which VPc = VBso, a power supply current IP (IP(0) > 0) flows through the battery 1 from the beginning of this voltage continuous application step S27.

[0133] Furthermore, when determining the magnitude of the incremental voltage ΔVP added to the initial open-circuit battery voltage VBso, the magnitude of the power supply current IP (power supply current value IP(0)) flowing through each battery 1 at the beginning of the voltage continuous application step S27 can be appropriately set in consideration. For example, the power supply current value IP(0) in the voltage continuous application step S27 can be set to a value (i) smaller than the steady-state power supply current value IPsgΔ corresponding to the self-discharge current ID of a typical good battery 1G. <IPsgΔ)、或者成为(ii)与稳定时电源电流值IPsgΔ相等的值(IP(0)=IPsgΔ)、或者成为(iii)与阈值电池1TH的阈值电流值IDth相等的值(IP(0)=IDth)、或者成为(iv)等于与典型的不合格电池1N的自放电电流ID对应的稳定时电源电流值IPsnΔ的值(IP(0)=IPsvΔ)、或者成为(v)大于稳定时电源电流值IPsnΔ的值(IP(0)> The magnitude of the incremental voltage ΔVP is determined by the method of IPsnΔ).

[0134] Therefore, in this embodiment 2 (refer to Figures 7 to 9 ), the incremental voltage ΔVP is set to a threshold incremental voltage ΔVPth such that the power source current value IP(0) of the power source current IP flowing through the battery 1 at the beginning of the voltage continuous application step S27 (voltage application time t=0) becomes a threshold current value IPth equal to the threshold current value IDth of the self-discharge current ID allowed by each battery 1. Thus, the characteristics of each battery 1 (conforming battery 1G, defective battery 1N, threshold battery 1TH) after the start of the voltage continuous application step S27 are similar to those of the aforementioned variant 1 (see Figure 5 )Similarly (refer to Figure 9 ).

[0135] That is, in the voltage continuous application step S27, as in Figure 9As indicated by the thick solid line in the upper graph of FIG, a continuous power supply voltage VPc having a magnitude obtained by adding the threshold incremental voltage ΔVPth to the measured initial open-circuit battery voltage VBso is continuously applied. Thus, at the beginning of the continuous voltage application step S27 (voltage application time t=0), a power supply current IP having a power supply current value IP(0) (=IPth) equal to the threshold current value IPth flows through each battery 1.

[0136] Here, when the battery 1 to be tested is the threshold battery 1TH, the power supply current value IP(0) of the power supply current IP is equal to the magnitude of the self-discharge current ID of the threshold battery 1TH (threshold current value IDth). Figure 9 As indicated by the thick single-dot chain line in the lower graph, the power supply current IP is stable from the initial stage of the voltage continuous application step S27, and remains equal to the threshold current value IPth even after the voltage application time t has passed.

[0137] On the other hand, in the case where the battery 1 to be tested is a non-conforming battery 1N, Figure 9 As indicated by the thick dashed line in the lower graph of , at the beginning of the voltage application step S27 (voltage application time t=0), a power supply current IP (IP(0)) having a threshold current value IPth flows. However, thereafter, the power supply current IP gradually increases and stabilizes at a stable power supply current value IPsnΔ that is slightly higher than the stable power supply current value IPsn of the defective battery 1N in the reference mode indicated by the thin dashed line.

[0138] On the other hand, when the battery 1 to be tested is a qualified battery 1G, Figure 9 As indicated by the thick solid line in the lower graph of , at the beginning of the voltage application step S27 (voltage application time t = 0), a power supply current IP (IP(0)) of the threshold current value IPth flows, similar to the threshold battery 1TH and the defective battery 1N. However, thereafter, the power supply current IP decreases rapidly and stabilizes at a stable power supply current value IPsgΔ that is slightly higher than the stable power supply current value IPsg of the good battery 1G in the reference system.

[0139] Therefore, in this second embodiment, similar to the first variation, the self-discharge state of battery 1 can be determined in "determination step" S10 using the power supply current value IP(n) obtained after the start of the voltage continuous application step S27 (voltage application time t=0). Thus, the method of this second embodiment makes it possible to determine the condition of battery 1 much earlier than conventional methods.

[0140] As described above, in the method of Embodiment 2, as with the conventional inspection method, the power supply current IP flowing through the battery 1 under test can be stabilized in advance, and the self-discharge inspection can be performed in advance. In the manufacturing method of Embodiment 2, the presence or absence and the degree of short circuit at the initial stage of the battery 1 can be appropriately inspected in a short time, and the battery 1 can be manufactured.

[0141] In the inspection method of Embodiment 2, the constant power supply voltage VPc obtained by adding the same increment voltage ΔVP to the initial open-circuit battery voltage VBso is applied to each battery 1 under test, and thus the voltage constant application process S27 can be performed under equal conditions. In this inspection method, the inspection can be performed without using the constant current mode or using the external power supply EP2 that does not have the constant current mode.

[0142] In addition, according to the inspection method of Embodiment 2, as described above, the tendency of change differs depending on whether the battery 1 is a good battery 1G or a defective battery 1N. Thus, even without waiting for the stabilization of the power supply current IP, it is possible to easily determine whether the battery 1 under test is a good battery 1G having a self-discharge current ID smaller than the threshold current value IPth (= IDth) or a defective battery 1N by detecting whether the power supply current IP decreases or increases from the threshold current value Ipth or is in a decreasing tendency or an increasing tendency after the start of the voltage constant application process S7, and thus the determination can be performed even more in advance.

[0143] The present application has been described above in connection with Embodiments 1 and 2 and Variations 1 and 2, but the present application is not limited to the above-described embodiments and the like, and can be appropriately changed and applied within the scope of the gist thereof, which is self-evident.

[0144] For example, in Embodiments 1 and 2 and Variations 1 and 2, the inspection processes of the self-discharge inspection of the battery 1 shown in the initial constant current circulation process S6 to the determination process S10 and the initial battery voltage measurement process S26 to the determination process S10 are performed during the manufacturing process of the battery 1. In contrast, these inspection processes can also be applied to the self-discharge inspection of the used battery 1 that has already been put into use on the market.

[0145] In addition, in Embodiments 1 and 2 and Variations 1 and 2, the threshold current value IPth is used to determine whether the battery 1 is good or not. However, a plurality of different threshold current values can be used to classify the battery 1 into three or more levels.

Claims

1. A method for inspecting the self-discharge of an electric storage device (1), comprising: A voltage continuous application step (S7, S27) of continuously applying a continuous power supply voltage (VPc) of a fixed magnitude higher than the first device voltage (VBso) from an external power supply (EP1, EP2) to the power storage device (1) previously charged to the first device voltage (VBso); a current detection step (S8, S28) of detecting a power supply current (IP, IP(n)) flowing from the external power supply (EP1, EP2) through the power storage device (1); and The determination step (S10) determines the self-discharge state of the power storage device (1) based on the detected power supply current (IP, IP(n)). Before the voltage continuous application step (S7), an initial constant current flow step (S6) is further provided. In the initial constant current flow step (S6), a constant current of a predetermined initial current value (IP0) is flowed from the external power supply (EP1) set in a constant current power supply mode to the power storage device (1). The voltage continuous application step (S7) following the initial constant current flow step (S6) is a step of continuously applying the continuous power supply voltage (VPc) having a magnitude equal to the initial power supply voltage (VP0) generated in the external power supply (EP1) when a constant current having the initial current value (IP0) flows through the power storage device (1) in the initial constant current flow step (S6).

2. The self-discharge inspection method of the electric storage device (1) according to claim 1, wherein: The initial current value (IP0) is set to a value equal to a threshold current value (IDth) of a self-discharge current (ID) set for the power storage device (1).

3. A method for inspecting the self-discharge of an electric storage device (1), comprising: A voltage continuous application step (S7, S27) of continuously applying a continuous power supply voltage (VPc) of a fixed magnitude higher than the first device voltage (VBso) from an external power supply (EP1, EP2) to the power storage device (1) previously charged to the first device voltage (VBso); a current detection step (S8, S28) of detecting a power supply current (IP, IP(n)) flowing from the external power supply (EP1, EP2) through the power storage device (1); and The determination step (S10) determines the self-discharge state of the power storage device (1) based on the detected power supply current (IP, IP(n)). Before the voltage continuous application step (S27), a first device voltage measurement step (S26) is further provided. In the first device voltage measurement step (S26), the magnitude of the first device voltage (VBso) of the power storage device (1) is measured. The voltage continuous application step (S27) following the first device voltage measuring step (S26) is a step of continuously applying the continuous power supply voltage (VPc) having a magnitude obtained by adding a predetermined incremental voltage (ΔVP) to the first device voltage (VBso).

4. The self-discharge inspection method of the electric storage device (1) according to claim 3, wherein: The incremental voltage (ΔVP) is set to a threshold incremental voltage (ΔVPth) at which a power supply current having a magnitude equal to a threshold current value (IDth) of a self-discharge current (ID) allowed by the power storage device (1) flows at the beginning of the voltage continuous application step (S27).

5. A method for manufacturing an electric storage device, comprising: an initial charging step of initially charging the assembled uncharged power storage device to a predetermined charge state to prepare the device as a pre-charged power storage device; and The inspection step is to inspect the self-discharge state of the initially charged electricity storage device by the self-discharge inspection method of the electricity storage device according to any one of claims 1 to 4.

Images