Methods for adjusting the voltage of energy storage devices

Abstract

A method for adjusting the device voltage of an energy storage device is provided. The method adjusts the component voltage of the energy storage device. When the energy storage device is represented by an equivalent circuit (Ec) that connects the capacitive device component (1B) and the short-circuit resistance (Rp) representing the magnitude of the self-discharge of the device component in parallel with the DC resistance (Rs) of the energy storage device in series, the energy storage device has the characteristic that when the load is reduced, the component voltage decreases and when the load is increased, the component voltage increases when the load is reduced, under the condition that the load applied to the energy storage device which is pressed by a first load (BL1) and generates a first component voltage (VBB1) in the device component changes from the first load. The method includes a component voltage change step (S8, S19, S24, S33) that utilizes the load change to change the component voltage from the first component voltage.

Description

Technical Field

[0001] This invention relates to a device voltage adjustment method for adjusting the device voltage of an energy storage device. Background Technology

[0002] Lithium-ion secondary batteries (hereinafter referred to as Battery 1) and other energy storage devices are generally used Figure 1 The equivalent circuit Ec shown is used to represent this. That is, the equivalent circuit Ec of battery 1 consists of three components: a capacitive battery component (device component) 1B, a short-circuit resistance Rp, and a DC resistance Rs. It is represented by a circuit structure formed by connecting a parallel circuit Pc in series with the DC resistance Rs. This parallel circuit Pc is formed by connecting battery component 1B and short-circuit resistance Rp in parallel. Battery component 1B is the capacitive component formed by battery (energy storage device) 1, and is assumed to generate a component voltage VBB when charged. The DC resistance Rs is considered to be the battery resistance existing in series with battery component 1B between the two terminal members 30 and 40 of battery 1. On the other hand, the short-circuit resistance Rp represents the magnitude of self-discharge caused by an internal short circuit in battery component 1B. The self-discharge current ID, indicated by the dashed arrow, represents the self-discharge current flowing from battery component 1B to the short-circuit resistance Rp.

[0003] Furthermore, when the battery (energy storage device) 1 is connected to an external power source EP using probes P1 and P2, contact resistance is generated between one probe P1 of the external power source EP and the positive terminal component 30 of the battery 1, and between the other probe P2 of the external power source EP and the negative terminal component 40 of the battery 1. Figure 1 In this context, their sum is represented as the contact resistance R12. Additionally, wiring resistance Rw is generated distributed within the external power supply EP and from the external power supply EP to probes P1 and P2. The current flowing from the external power supply EP to battery 1 is defined as the power supply current IP, and the voltage generated between the two terminal components 30 and 40 of battery 1 is defined as the battery voltage VB.

[0004] Furthermore, when the power supply current IP is zero (IP = 0), the component voltage VBB generated in battery component 1B is the same as the battery voltage VB generated between the two terminal members 30 and 40 of battery 1. From this phenomenon, it can be understood that the component voltage VBB is also equivalent to the open circuit voltage (OCV) of battery 1.

[0005] However, during the various stages of manufacturing, testing, or using energy storage devices such as battery 1, it is sometimes desirable to make the battery voltage (device voltage) VB (i.e., component voltage VBB) in the open-circuit state match the reference voltage, or to change the component voltage VBB to another value, or to change the magnitude of the battery voltage VB under current flow conditions. In such cases, battery 1 is connected to an external power source EP and charged or discharged to make the battery voltage VB (component voltage VBB) reach the desired value.

[0006] Conversely, sometimes the battery voltage VB is measured beforehand, and a power supply voltage equal to the open-circuit battery voltage VB (component voltage VBB) is applied to the battery 1 from an external power source EP. Furthermore, as prior art related to the latter, Patent Document 1 is cited (see the claims of Patent Document 1, etc.).

[0007] Existing technical documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2019-16558 Summary of the Invention

[0009] Furthermore, there are slight differences in the characteristics of each battery (energy storage device) 1, including differences in the magnitude of the self-discharge current ID (the magnitude of the short-circuit resistance Rp). Therefore, even if multiple batteries 1 are charged to the same component voltage VBB, the magnitudes of their respective component voltage VBBs will differ due to the passage of time, temperature changes, etc. For example, if multiple batteries 1 charged to the same component voltage VBB are subjected to the same high-temperature aging (e.g., 63°C × 20 hours) and then cooled, the component voltage VBBs of each battery 1 will not become the same, but will deviate slightly.

[0010] On the other hand, when testing or inspecting these multiple batteries (energy storage devices) 1 under the same conditions, it is sometimes desirable to start the test after aligning the component voltage VBB with the reference voltage. Such situations, where it is desirable to align the component voltage VBB with the reference voltage, may occur at various stages of the manufacturing, testing, and use of the battery (energy storage device) 1.

[0011] On the other hand, regarding a battery (energy storage device) that is being charged and subjected to a load, the inventors have discovered that when the applied load is reduced, the component voltage (open circuit voltage) decreases slightly, and conversely, when the load is increased, the component voltage (open circuit voltage) increases slightly.

[0012] The present invention was made in view of the above findings, and its object is to provide a method for adjusting the component voltage of an energy storage device.

[0013] (1) One aspect of the present invention for solving the above problems is a device voltage adjustment method for an energy storage device. The energy storage device has the following characteristics: when the energy storage device is represented by an equivalent circuit in which a parallel circuit of a capacitive device component and a short-circuit resistor representing the magnitude of the self-discharge of the device component is connected in series with the DC resistance of the energy storage device, the energy storage device has the following characteristics: when the device component is charged and a component voltage is generated under load, the component voltage decreases when the load is reduced and increases when the load is increased. The device voltage adjustment method includes a component voltage change step that utilizes load change. In this component voltage change step that utilizes load change, the load applied to the energy storage device that is pressed by a first load and generates a first component voltage in the device component is changed from the first load, thereby changing the component voltage from the first component voltage.

[0014] The energy storage device inspected using the above adjustment method has the following characteristics as described above: when the load applied to the energy storage device is reduced, the component voltage (open circuit voltage) decreases; on the other hand, when the load is increased, the component voltage increases.

[0015] Furthermore, the above-described adjustment method includes a component voltage variation step that utilizes load variation to change the component voltage by changing the load applied to the energy storage device from a first load. Therefore, in this device voltage adjustment method, the component voltage (open-circuit voltage) of the energy storage device can be varied and adjusted independently of charging and discharging. Alternatively, the current flowing through the energy storage device can be adjusted by adjusting the component voltage of the energy storage device.

[0016] The aforementioned method for adjusting the voltage of energy storage devices can be implemented not only during the manufacturing process of the devices, but also during use after they are installed in vehicles or other devices, or after they have been put into the market independently. Furthermore, it can also be implemented during performance verification tests of energy storage devices conducted during the development and mass production stages.

[0017] In addition, as "energy storage devices", examples include secondary batteries such as lithium-ion secondary batteries, and capacitors such as double-layer capacitors and lithium-ion capacitors.

[0018] As mentioned above, the component voltage is equivalent to the open-circuit voltage generated between the terminals of the energy storage device when the current flowing from the outside to the energy storage device is zero, and it is not necessary to disconnect the terminals of the energy storage device from the circuit (open circuit) for measurement.

[0019] As for the load change performed in the process of utilizing the component voltage change of load variation, patterns in which the first load is monotonically decreased and patterns in which the first load is monotonically increased are listed. Patterns in which the load is increased or decreased are also listed. Among the patterns in which the load is increased or decreased, patterns in which the load is temporarily decreased and then increased, or temporarily increased and then decreased, are also listed. Furthermore, patterns in which the load is repeatedly increased or decreased are also included.

[0020] (2) In the device voltage adjustment method of the energy storage device in (1), it is preferable to further include a component voltage detection step for detecting the first component voltage of the energy storage device pressed by the first load before the component voltage change step utilizing the load change. The component voltage change step utilizing the load change is a reference voltage conversion step utilizing the load change to make the changed component voltage after the load change applied to the energy storage device equal to the reference component voltage.

[0021] In this device voltage adjustment method, during the reference voltage conversion step utilizing load changes, the load applied to the energy storage device is changed from a first load, thereby changing the component voltage from the first component voltage to a changed component voltage equal to the reference component voltage. In other words, the component voltage of the energy storage device can be adjusted to the reference component voltage without relying on charging or discharging. Furthermore, if this method is applied to multiple energy storage devices, the changed component voltage can be made consistent with the reference component voltage for any given energy storage device.

[0022] (3) In the device voltage adjustment method of the energy storage device in (1), it is preferable to further include a multiple component voltage detection step before the above-mentioned component voltage change step utilizing load change, which detects the first component voltage of the multiple energy storage devices pressed by the first load. When the first component voltage generated by the reference energy storage device selected from the multiple energy storage devices is set as the reference first component voltage, and the energy storage devices other than the reference energy storage device and whose first component voltage is different from the reference first component voltage are set as the energy storage devices to be adjusted, the above-mentioned component voltage change step utilizing load change is a component voltage homogenization step utilizing load change, which makes the component voltage after the load change of the energy storage device applied to the energy storage device equal to the reference first component voltage.

[0023] In this device voltage adjustment method, during the load change component voltage homogenization step, the load applied to the energy storage device being adjusted is changed from a first load so that the changed component voltages of multiple energy storage devices are all equal to the reference first component voltage. In other words, it is possible to make the changed component voltages of multiple energy storage devices consistent with the reference first component voltage without depending on the charging and discharging of the energy storage devices.

[0024] (4) In the device voltage adjustment method of the energy storage device in (1), the component voltage change process utilizing load change is preferably a reference total voltage conversion process utilizing load change, in which the total component voltage obtained by adding up all the component voltages of the multiple energy storage devices is equal to the reference total component voltage.

[0025] In this device voltage adjustment method, the total component voltage of multiple energy storage devices is made equal to the reference total component voltage during the reference total voltage conversion process based on load changes. In other words, it is possible to make the total component voltage of multiple energy storage devices consistent with the reference total component voltage without depending on the charging and discharging of the energy storage devices.

[0026] Alternatively, multiple energy storage devices can be connected in series and the total component voltage can be measured to obtain the total component voltage. Or, the individual component voltages can be added together without connecting multiple energy storage devices to calculate the total component voltage. Attached Figure Description

[0027] Figure 1 It is a circuit diagram of a battery connected to an external power source, including its equivalent circuit.

[0028] Figure 2 These are longitudinal cross-sectional views of the batteries involved in embodiments 1 to 3 and variations 1 and 2.

[0029] Figure 3 An explanatory diagram showing the state in which the batteries according to Embodiments 1, 2 and their variations 1, 2 are mounted on a fixture capable of increasing or decreasing the load.

[0030] Figure 4 According to Embodiment 1, there is a flowchart of a battery manufacturing process having an inspection process that includes a self-discharge inspection of the battery, which includes a load change process.

[0031] Figure 5 The modified method 1 is a flowchart of a battery manufacturing process that includes a battery self-discharge inspection process that includes a load change process.

[0032] Figure 6 The present invention relates to Embodiment 2 and its variant 2, and is a flowchart of a process for adjusting the voltage of multiple batteries and connecting them in parallel, including a load change process.

[0033] Figure 7 The embodiment 3 is an explanatory diagram showing a state in which multiple batteries stacked and connected in series are installed into a fixture that allows for the increase or decrease of load.

[0034] Figure 8Implementation method 3 is a flowchart of a total voltage adjustment process for multiple batteries connected in series, including a load change process.

[0035] (Symbol Explanation)

[0036] 1: (Completed charging) battery (energy storage device); 1r: Reference battery (reference energy storage device); 1c: Adjusted battery (adjusted energy storage device); 1G: Battery pack; S2: Load application process; KJ, PKJ: Restraining jig; S7: Initial battery voltage measurement process (inspection process, component voltage detection process); S8: Load change process (inspection process, component voltage change process using load change, reference voltage conversion process using load change); BL: (Applied load to the battery) load; BL1: First load; BLa, BLb, BLc, BLd: Load after change; S9, S18: Continued voltage application process (inspection process); S10: Current detection process (inspection process); S11: Continued judgment process (inspection process); t: Voltage application time; S12: Judgment process (inspection process); S19: Load change process (inspection process, using load change) S21: Load application process; S22: Battery voltage measurement process (multiple component voltage detection process); S23: Reference / adjusted battery selection process; S24: Load change process (using load change component voltage change process, using load change component voltage homogenization process); S25: Adjustment detection process; S26: Parallel connection process; S27: Series connection process; S31: Stacking-load application-series connection process; S32: Total battery voltage measurement process; S33: Load change process (using load change component voltage change process, using load change reference total voltage conversion process); T B: Battery temperature (device temperature); TB1: First battery temperature (first device temperature); VB: Battery voltage (device voltage); SVB: Total battery voltage; VB1: First battery voltage; VBr: Reference battery voltage; VBa, VBc: (After load change) Changed battery voltage; SVBd: (After load change) Total changed battery voltage; EP: External power supply; VP: (External power supply) Power supply voltage; VPc: Continuous power supply voltage; IP: Power supply current; IP(n): (Acquired) Power supply current value; IPr: Reference power supply current; 1B: Battery component (device component); VBB: (Battery component generated) component Voltage; VBB1: First component voltage; VBBr: Reference component voltage; SVBB: Total component voltage; SVBBr: Reference total component voltage; ΔVBB: Component voltage change; VBBa, VBBb, VBBc: (After load change) Changed component voltage; SVBBd: (After load change) Changed total component voltage; Rs: (Battery) DC resistance (DC resistance of the energy storage device); Rp: (Battery) Short-circuit resistance (Short-circuit resistance of the energy storage device); ID: Self-discharge current; Pc: (Battery component and short-circuit resistance) Parallel circuit; Ec: (Battery) Equivalent circuit (Equivalent circuit of the energy storage device). Detailed Implementation

[0037] (Implementation Method 1)

[0038] Hereinafter, Embodiment 1 of the present invention will be described with reference to the accompanying drawings. Figure 2 The figure shows a longitudinal cross-sectional view of the lithium-ion secondary battery 1 according to Embodiment 1. The battery 1 comprises a cuboid-shaped battery casing 10, a flat, wound electrode body 20 housed within it, an electrolyte 15, and positive terminal components 30 and negative terminal components 40 supported by the battery casing 10. In Embodiment 1, 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. Furthermore, the batteries 1 described later in variations 1, 2, 2, and 3 are also the same.

[0039] Next, a self-discharge inspection method for determining the insulation properties inside battery 1 and a manufacturing method for battery 1 including the self-discharge inspection method will be described (see reference). Figure 4 First, in the "assembly process" S1, the uncharged battery 1X is assembled (see...). Figure 2 The initial battery voltage measurement process S7 to the judgment process S12, which will be described later, are equivalent to the inspection processes in the manufacturing method of battery 1.

[0040] Next, in the "load application process" S2, a predetermined first load BL1 (in this embodiment 1, for example, BL1 = 918 kgf = 9 kN) is applied to the assembled battery 1X (the rear battery 1) as load BL. Specifically, as Figure 3 As shown, the limiting clamp KJ is used to constrain the battery in the thickness direction using the first load BL1 (in Figure 2 The battery 1 (battery 1X) is elastically compressed in a direction perpendicular to the paper. More specifically, the battery 1 (battery 1X) is clamped between the lower fixing plate KJP1 and the pressure plate KJMP, which are fixed by the support column KJC and the fixing nut KJN of the limiting clamp KJ. The columnar pressing member KJMC is elastically pushed by its external threaded portion KJMCs, the pressing nut KJMN and the compression spring KJMS, thereby applying a load BL to the battery 1 (battery 1X).

[0041] Furthermore, by pre-positioning a load cell (not shown) instead of battery 1 between the fixed plate KJP1 and the pressure plate KJMP and tightening the pressing nut KJMN, the relationship between the length LL of the compression spring KJMS (the distance between the washers KJMW on both sides of the compression spring KJMS) and the load applied to the load cell is obtained. Therefore, by measuring the length LL of the compression spring KJMS, the magnitude of the load BL applied to battery 1 using the limiting clamp KJ can be detected.

[0042] While maintaining the first load BL1 applied to battery 1 (battery 1X), the initial charging step S3 to the subsequent judgment step S11 are performed on battery 1. In each step, a temperature detection device KTS having a temperature sensor KT composed of a thermistor is used to detect the ambient temperature TK around battery 1. Additionally, a temperature detection device STS having a temperature sensor ST composed of a thermistor in contact with a predetermined position on battery casing 10 is used to detect the battery temperature TB (see reference). Figure 1 ).

[0043] Next, in the "initial charge process" S3, the uncharged battery 1X is initially charged and designated as battery 1. At the initial charge temperature FT (FT = 20°C), a charging and discharging device (not shown) is connected to the two terminal components 30 and 40 of the battery 1X, which is constrained by the limiting clamp KJ. The battery 1 is initially charged by constant current constant voltage (CCCV) charging until the battery voltage VB of the battery 1X reaches a predetermined value (VB = 4.0V in this embodiment).

[0044] Next, in the "high-temperature aging process" S4, the initially charged battery 1 is placed in the aging period EK (EK = 20 hours) at an aging temperature ET (ET = 63°C) with the two terminal components 30 and 40 in an open circuit state for high-temperature aging. If this high-temperature aging is performed, the battery voltage VB of battery 1 will decrease, becoming a battery voltage equivalent to approximately 80% of SOC.

[0045] Next, in the "cooling process" S5, battery 1 is placed in the cooling chamber CR at a cooling temperature CT (CT = 20°C) for 20 minutes, and forced cooling is performed using a fan, thereby bringing the battery temperature TB to approximately 20°C (TB ≈ 20°C) (see reference). Figure 4 ).

[0046] Furthermore, in the "placement process" S6, battery 1 is transferred to the first chamber KR1 where the ambient temperature TK is set to a first ambient temperature TK1 (TK1 = 20.0°C) and placed for a placement period HP (e.g., HP = 30 minutes), so that the battery temperature TB of battery 1 becomes the same as the first ambient temperature TK1, a first battery temperature TB1 (TB1 = 20.0°C) (see reference). Figure 4 Then, after the placement step S6, the initial battery voltage measurement step S7 to the continued judgment step S11, which will be described later, are also performed under the condition that the battery temperature TB of battery 1 is the first battery temperature TB1.

[0047] In the "Initial Battery Voltage Measurement Step" S7, the open-circuit voltage, i.e., the first battery voltage VB1, of battery 1, set at a first ambient temperature TK1 and a first battery temperature TB1 (TB1 = 20.0℃), is measured. Specifically, as... Figure 1 As shown, a pair of probes P1 and P2 of the external power supply EP are made to contact the positive terminal component 30 and the negative terminal component 40 of the battery 1 respectively. The external power supply EP is connected to the battery 1, and the power current IP flowing from the external power supply EP to the battery 1 is set to zero (IP = 0: the state of cutting off the DC voltage source EPE). The first battery voltage VB1 of the battery 1 is measured by the voltmeter EPV.

[0048] Figure 1 The external power supply EP used in Embodiment 1 and its variant 1 shown is a precision DC power supply capable of variablely and precisely controlling the power supply voltage VP generated by the DC voltage source EPE, and is a variable constant voltage power supply. In addition to having a voltmeter EPV capable of accurately measuring the power supply voltage VP applied to the battery 1, the external power supply EP also has a galvanometer EPI capable of precisely measuring the power supply current IP flowing from the external power supply EP to the battery 1.

[0049] As mentioned above, in Figure 1 In this context, the wiring resistance Rw represents the wiring resistance distributed within the external power supply EP and from the external power supply EP to probes P1 and P2. Additionally, the contact resistance R12 is the sum of the contact resistances generated between one probe P1 of the external power supply EP and the positive terminal component 30 of battery 1, and between the other probe P2 and the negative terminal component 40 of battery 1.

[0050] In addition, Figure 1The diagram also shows an equivalent circuit of battery 1, including battery component 1B, DC resistance Rs, and short-circuit resistance Rp. Battery component 1B is the capacitance component formed by battery 1, and is assumed to generate a component voltage VBB. The DC resistance Rs is the battery resistance that can be considered to exist in series with battery component 1B. On the other hand, the short-circuit resistance Rp represents the magnitude of self-discharge caused by an internal short circuit in battery 1. The self-discharge current ID, indicated by the dashed arrow, represents the self-discharge current flowing from battery component 1B to the short-circuit resistance Rp. The first battery voltage VB1 obtained in the initial battery voltage measurement step S7 corresponds to the open-circuit voltage of battery 1 at that time point, and the component voltage VBB of battery component 1B at that time point, i.e., the first component voltage VBB1, is consistent with the first battery voltage VB1 (VBB1 = VB1).

[0051] Furthermore, the initial battery voltage measurement step S7 is maintained (without reconnecting the pair of probes P1 and P2 to the terminal members 30 and 40) to the subsequent judgment step S11 (also in variant 1), while maintaining the connection state between probe P1 and the positive terminal member 30 and the contact state between probe P2 and the negative terminal member 40. This is to avoid the following situation: the contact state of probes P1 and P2 with respect to the terminal members 30 and 40 changes with each contact, thereby causing variations in 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.

[0052] Battery 1 has the following characteristics: when the load BL is reduced, the component voltage VBB of battery component 1B decreases, and when the load BL is increased, the component voltage VBB increases. Specifically, in the battery 1 of this embodiment 1, for example, it has the following characteristics: when the load BL is reduced from the first load BL1 (=9kN) to the load BL=0N (load change ΔBL=-9kN), the component voltage VBB decreases by 6μV compared to before the load change (component voltage change ΔVBB=-6μV).

[0053] Therefore, in the "load change process" S8, this characteristic is utilized to rotate the pressing nut KJMN, causing the load BL applied to the battery 1 by the limiting clamp KJ to decrease or increase from the first load BL1 mentioned above to become the changed load BLa (refer to...). Figure 3Furthermore, the pressing nut KJMN can be rotated in one direction, thereby monotonically decreasing or increasing the load BL (in one direction). This causes the component voltage VBB of battery 1 (= the battery voltage VB in the open circuit state) to slightly decrease or increase from the first component voltage VBB1 (= the first battery voltage VB1) measured in the initial battery voltage measurement step S7, becoming a changed component voltage VBBa (VBBa = VBBr) equal to the predetermined reference component voltage VBBr. Specifically, the changed component voltage VBBa after the load change is adjusted to a value within the range of VBBa = VBBr ± 1μV (for example, the reference component voltage VBBr can be VBBr = 3.800000V). Additionally, the changed component voltage VBBa is equal to the battery voltage in the open circuit state after the load change (let's call it the changed battery voltage VBa) (VBBa = VBa). Therefore, the changed battery voltage VBa in the open circuit state after the load change step S8 becomes equal to the reference battery voltage VBr (= VBBr).

[0054] As described above, the load change process S8 makes the changed component voltage VBBa of a specific battery 1 equal to the reference component voltage VBBr (making the battery voltage VB equal to the reference battery voltage VBr). Furthermore, by applying the load change process S8 to multiple batteries 1 to be tested, the component voltage VBB of each battery 1 can also be made equal to the reference component voltage VBBr (making the battery voltage VB equal to the reference battery voltage VBr), thus making their component voltages VBB (battery voltage VB) consistent.

[0055] In the subsequent "voltage continued application step" S9, at the first ambient temperature TK1, when the first battery temperature TB1 is equal to the first ambient temperature TK1, the DC voltage source EPE of the external power supply EP generates a continued power supply voltage VPc (VPc = VBa) equal to the changed battery voltage VBa generated in the load change step S8 described above, and begins to apply it to battery 1 (voltage application time t = 0), thereafter continuing to apply the continued power supply voltage VPc. That is, the continued power supply voltage VPc generated by the external power supply EP is maintained at a magnitude equal to the initial changed battery voltage VBa. Thus, VPc = VBa, and therefore, similar to Patent Document 1, at the beginning of this voltage continued application step S9, no power supply current IP flows through battery 1. In this embodiment 1, since it is not necessary to change the continued power supply voltage VPc generated by the external power supply EP for each battery 1, it is sufficient to use a constant voltage source set to a predetermined reference battery voltage VBr (= reference component voltage VBBr) as the external power supply EP.

[0056] When a continuous power supply voltage VPc, equal to the changed battery voltage VBa, is continuously applied to battery 1 from an external power source EP, as the voltage application time t elapses, the component voltage VBB of battery component 1B gradually decreases from the changed component voltage VBBa at the start of the voltage application process S9 (t=0). This is because the charge accumulated in battery component 1B is gradually discharged through the short-circuit resistor Rp via the self-discharge current ID.

[0057] Therefore, initially, after the change in battery voltage VBa is applied (voltage application time t = 0), no power supply current IP flows (IP(0) = 0). However, as the component voltage VBB generated by battery component 1B decreases, such as from Figure 1 It can be easily understood that a potential difference (VPc-VBB) is generated across the circuit DC resistance Rcs obtained by adding the DC resistance Rs, the contact resistance R12, and the wiring resistance Rw. The corresponding power supply current IP flows through battery 1 along the path shown by the double-dotted arrow (VPc=VBB+(Rs+R12+Rw)·IP).

[0058] Furthermore, the magnitude of the power supply current IP gradually increases as the component voltage VBB of battery component 1B decreases. However, as from... Figure 1 It is understandable that as the component voltage VBB decreases and the supply current IP increases, when the back electromotive force Vp generated in the short-circuit resistor Rp (Vp = Rp·IP) becomes equal to the component voltage VBB generated in battery component 1B, the self-discharge current ID will no longer flow from battery component 1B. Therefore, the decrease in the component voltage VBB in battery component 1B also stops, and the supply current IP becomes equal to the inherent self-discharge current ID (the steady-state supply current) that varies for each battery 1 and stabilizes.

[0059] Therefore, in the "current detection process" S10, the power supply current IP is detected by the ammeter EPI.

[0060] In the following "continued judgment process" S11, it is determined whether to repeat the voltage continued application process S9 and the current detection process S10. In this embodiment 1, after the continuous power supply voltage VPc is applied to the battery 1, it is determined whether the power supply current IP is stable. Here, if "no", that is, the power supply current IP is unstable, the process returns to the voltage continued application process S9, and the continuous power supply voltage VPc is applied to the battery 1 again (S9), and the power supply current IP is detected again (S10). On the other hand, if "yes", that is, the power supply current IP is stable, the process proceeds to the "judgment process" S12, which will be described later.

[0061] In addition, in the continuation determination step S11, as a method for determining whether the power supply current IP is stable, for example, the following method is listed: successively calculate the moving average of the values of the power supply current IP obtained in the current detection step S10 (for example, the moving average of 7 power supply current values IP(n - 6) to IP(n) obtained during the most recent 60 seconds), and determine whether the power supply current IP is stable based on the trend of this moving average (for example, the magnitude of the difference value or the differential value of the moving average).

[0062] In the "determination step" S12, based on the obtained power supply current IP, specifically, the value IP(n) of the power supply current IP obtained after the start of the voltage continuation application step S9 (voltage application time t = 0) is used to determine the self-discharge state of the battery 1.

[0063] In the first embodiment, specifically, the moving average MIP(n) of a plurality (for example, 7) of the power supply current values IP(n - 6) to IP(n) that are finally obtained in the continuation determination step S11 among a series of power supply current values IP(0), IP(1),..., IP(n) obtained at a predetermined time interval (in this embodiment, every 10 seconds) in the current detection step S10 is set as the final average power supply current value IPE. This final average power supply current value IPE represents the value of the stable power supply current obtained at the end of the voltage continuation application step S9, that is, the magnitude of the self-discharge current ID. Therefore, by comparing it with the threshold current value IPth, the battery 1 with the final average power supply current value IPE less than the threshold current value IPth (IPE < IPth) is determined to be a qualified product. In this way, it is possible to manufacture the battery 1 that is charged and inspected for the self-discharge state and is a qualified product.

[0064] On the other hand, the battery 1 with the final average power supply current value IPE being greater than or equal to the threshold current value IPth (IPE ≥ IPth) is determined to be defective. The battery 1 determined to be defective is excluded and discarded. Or, it is recycled by decomposition or the like.

[0065] In the method of this embodiment 1, by employing a load change process S8 in the self-discharge check of the initial battery voltage measurement process S7 to the judgment process S12 in the battery 1 manufacturing process, it is possible to change and adjust the component voltage VBB (open-circuit battery voltage VB) of battery 1 independently of charging and discharging the battery 1 before the voltage application continuation process S9. Specifically, the component voltage VBB of battery 1 can be adjusted to the reference component voltage VBBr independently of charging and discharging. Furthermore, for any battery among the plurality of batteries 1, the changed component voltage VBBa can be made consistent with the reference component voltage VBBr. Therefore, the voltage application continuation process S9 can be started when the changed component voltage VBBa of battery 1 is consistent with the reference component voltage VBBr.

[0066] (Transformation Method 1)

[0067] In the above-described embodiment 1, in the load change step S8 of the self-discharge check, the load BL applied to the battery 1 is reduced or increased from the first load BL1 to become the changed load BLa, the component voltage VBB of the battery 1 is decreased or increased from the first component voltage VBB1 to become the changed component voltage VBBa equal to the reference component voltage VBBr, and the battery voltage VB in the open circuit state becomes the changed battery voltage VBa equal to the reference battery voltage VBr. That is, in the load change step S8, the load BL applied to the battery 1 is changed in such a way that the battery voltage VB is equal to the reference battery voltage VBr.

[0068] However, it is also possible to change the load BL applied to the battery 1 in such a way that the power supply current IP flowing from the external power supply EP to the battery 1 becomes a changed power supply current IPa equal to the reference power supply current IPr, thereby changing the component voltage VBB of the battery 1.

[0069] Furthermore, in this modified embodiment 1, the difference lies in that the load change process S8 and the voltage continuing application process S9 in embodiment 1 are replaced by the voltage continuing application process S18 and the load change process S19, but the rest are the same. Therefore, the description focuses on the different parts, and the description of the same parts is omitted or simplified.

[0070] That is, in Figure 5In the initial battery voltage measurement step S7 of the self-discharge check (S7, S18, S19, S10-S12) performed in the manufacturing process of battery 1 in the modified embodiment 1 shown, the first battery voltage VB1 is measured. In the subsequent voltage application step S18, unlike embodiment 1, the load change step S8 is not performed, and a continuing power supply voltage VPc equal to the first battery voltage VB1 measured in the initial battery voltage measurement step S7 is applied to battery 1, and this application continues.

[0071] On the other hand, parallel to the voltage application process S18, the load change process S19 is started quickly after the voltage application process S18 begins (e.g., within 1 minute of the voltage application time t). This reduces the first load BL1 applied to the battery 1 to the changed load BLb in such a way that the changed power supply current IPa flowing from the external power source EP to the battery 1 is equal to the reference power supply current IPr (e.g., IPa = IPr = 30μA), causing the component voltage VBB of the battery 1 to drop to the changed component voltage VBBa. Thus, in the initial stage of the voltage application process S18, the changed power supply current IPa, equal to the reference power supply current IPr, can flow through any battery 1 through the load change process S19, accelerating the convergence of the power supply current IP. Furthermore, during the self-discharge check of each battery 1, the magnitude of the power supply current IP in the initial stage of the voltage application process S18 can be made consistent with the changed power supply current IPa (= reference power supply current IPr), making it easier to determine whether the battery 1 is qualified.

[0072] In this modified method 1, by employing a load change step S19 in parallel with the voltage application step S18 during the self-discharge check, the component voltage VBB of battery 1 can be changed independently of the charging and discharging of battery 1, thereby adjusting the changed power supply current IPa flowing through battery 1. Therefore, after the load change step S19, the voltage application step S18 can continue while ensuring that the changed power supply current IPa of battery 1 is consistent with the reference power supply current IPr.

[0073] Furthermore, the power supply current IP is less susceptible to external noise compared to the battery voltage VB, and it can be measured at all points through which the power supply current IP flows. This also facilitates changes in the magnitude of the power supply current IP by varying the load BL applied to the battery 1 during a load change process, thereby changing the component voltage VBB of the battery 1 and ensuring that the power supply current IP flowing through the battery 1 matches the reference power supply current IPr.

[0074] (Implementation Method 2)

[0075] In this embodiment 2, a plurality of batteries 1, each having a first load BL1 applied by a limiting clamp KJ, will be described (see reference 1). Figure 2 , Figure 3 The open-circuit state of the battery voltage VB is consistent with the voltage adjustment, or it is further connected in parallel.

[0076] First, in the "load application process" S21, multiple batteries 1 (refer to) that are charged to the same battery voltage VB are used with the limiting clamp KJ. Figure 2 , Figure 3 ) constrained to have a first load BL1 in the battery thickness direction (in Figure 2 The battery 1 is in a state of elastic compression in the direction perpendicular to the paper (the middle direction is perpendicular to the paper).

[0077] Subsequently, in the "Battery Voltage Measurement Process" S22, the first battery voltage VB1 (first component voltage VBB1 of battery component 1B) of multiple batteries 1 in the open-circuit state, which are at the first battery temperature TB1 (TB1 = 20.0°C) under the first ambient temperature TK1, is measured respectively (refer to...). Figure 1 Furthermore, as already explained, in battery 1, the first battery voltage VB1 in the open-circuit state is equal to the first component voltage VBB1 of battery component 1B.

[0078] In the "Reference / Adjusted Battery Selection Process" S23, a reference battery 1r and an adjusted battery 1c are selected from a plurality of batteries 1. That is, a specific battery is selected from the plurality of batteries 1 as the reference battery 1r, and the first component voltage VBB1 generated in the selected reference battery 1r is set as the reference first component voltage VBB1r, and the first battery voltage VB1 in the open circuit state generated in the reference battery 1r is set as the reference first battery voltage VB1r. In addition, a battery 1 from the plurality of batteries 1 other than the reference battery 1r whose first component voltage VBB1 is different from the reference first component voltage VBB1r is set as the adjusted battery 1c.

[0079] Furthermore, it is sufficient to select any appropriate battery 1 from among the multiple batteries 1 as the reference battery 1r, but it is preferable to select the battery 1 with the highest first component voltage VBB1 as the reference battery 1r. This is because, in the load changing process S24 described below, the load BL applied to any adjusted battery 1c will be reduced, simplifying the operation of the limiting clamp KJ. Alternatively, conversely, it is also preferable to select the battery 1 with the lowest first component voltage VBB1 as the reference battery 1r. This is because, in the load changing process S24 described below, the load BL applied to any adjusted battery 1c will be increased.

[0080] In the "load change process" S24, for one or more adjusted batteries 1c selected in the reference / adjusted battery selection process S23, the load BL is changed, causing the component voltage VBB to change. That is, for the selected adjusted battery 1c, the limiting clamp KJ (refer to...) is... Figure 3 Rotating the pressing nut KJMN causes the load BL to decrease or increase from the first load BL1 to become the changed load BLc. This adjusts the component voltage VBB1 (= battery voltage VB in the open circuit state) of the adjusted battery 1c to the changed component voltage VBBc, which is equal to the reference first component voltage VBB1r (= reference first battery voltage VB1r) of the reference battery 1r.

[0081] In the "adjustment detection process" S25, for all selected batteries 1c to be adjusted, it is detected whether the adjustment of the component voltage VBB using load changes has been completed. If not completed (No), the process returns to step S24. On the other hand, for all batteries 1c to be adjusted, if the adjustment of the component voltage VBB using load changes has been completed (Yes), the voltage adjustment of multiple batteries 1 is terminated. Thus, for all batteries 1, regardless of charging or discharging, their component voltage VBB is made consistent with the reference first component voltage VBB1r of the reference battery 1r, and the battery voltage VB in the open circuit state is consistent with the reference first battery voltage VBB1r of the reference battery 1r.

[0082] Furthermore, the detection step S25 can be adjusted to connect multiple batteries 1 in parallel in the "parallel connection step" S26, indicated by dashed lines. In this case, as described above, the battery voltage VB of all batteries 1 in the open-circuit state is equal to the reference first battery voltage VBB1r. Therefore, even if they are connected in parallel, no current will flow due to the voltage difference. For any battery 1, the charging state (component voltage VBB) before connection can be maintained and the parallel connection state can begin.

[0083] (Transformation Method 2)

[0084] Alternatively, the inspection process S25 can be adjusted further. Figure 6 In the "series connection process" S27, indicated by a single-dotted line, multiple batteries 1 are connected in series. In this case, the battery voltage VB of all batteries 1 in the open-circuit state is also equal to the reference first battery voltage VBB1r. That is to say, batteries 1 with equal battery voltage VB can be connected in series to initiate the series connection state.

[0085] In this embodiment 2 and its variation 2, an example is shown where the battery voltage measurement step S22 is performed following the load application step S21. However, similarly to embodiment 1, the uncharged battery 1X may be loaded in the load application step S21, and then, similarly to embodiment 1, after performing the initial charging step S3 to the placement step S6, the first battery voltage VB1 may be measured in the battery voltage measurement step S22, and subsequent steps may be performed.

[0086] Furthermore, in both Embodiment 2 and its variant 2, a reference battery 1r and a battery 1c to be adjusted are selected in the reference / adjusted battery selection process S23. In the load change process S24, the load BL is changed for the adjusted battery 1c so that the component voltage VBB matches the reference first component voltage VBB1r. However, it is also possible not to select the reference battery 1r and the adjusted battery 1c, and instead, similarly to Embodiment 1, change the load BL for all of the multiple batteries 1 so that the component voltage VBB matches the predetermined reference component voltage VBBr.

[0087] (Implementation Method 3)

[0088] In this embodiment 3, the case of adjusting the total voltage of the battery pack 1G obtained by stacking and connecting multiple batteries 1 in series will be described.

[0089] First, in the "Layering-Load Imposition-Series Connection Process" S31, multiple batteries 1 (refer to) that will be charged to approximately the same battery voltage are... Figure 2 Stack them together and use Figure 7 The shown clamping fixture PKJ for multiple batteries is constrained by a common first load BL1 in the battery thickness direction (in Figure 2 The battery 1 is in a state of elastic compression (perpendicular to the paper surface). Furthermore, the battery 1 is connected in series with each other using terminal members 30 and 40 of multiple batteries 1.

[0090] Next, in the "Total Battery Voltage Measurement Process" S32, a first battery temperature TB1 (TB1 = 20.0°C) is set at a first ambient temperature TK1, and the total first battery voltage SVB1 of the multiple series-connected batteries 1 in the open-circuit state is measured. Furthermore, in the battery pack 1G composed of the multiple series-connected batteries 1, the total first battery voltage SVB1 in the open-circuit state is compared with the battery component 1B of each battery 1 (refer to...). Figure 1 The sum of the first component voltages VBB1 and VBB1 is equal to the total first component voltage SVBB1 (SVB1=SVBB1).

[0091] In the "load change process" S33, the pressing nut KJMN of the limiting clamp PKJ is rotated, causing the load BL applied to the multiple batteries 1 to decrease or increase from the first load BL1 to become the changed load BLd. This causes a change in the component voltage VBB (= battery voltage VB in the open circuit state) of each battery 1, and changes the total component voltage SVBB obtained by summing the component voltages VBB of each battery 1's component 1B from the total first component voltage SVBB1, adjusting it to become the changed total component voltage SVBBd equal to the reference total component voltage SVBBr (SVBBd = ​​SVBBr). This causes the total battery voltage SVB in the open circuit state to change from the total first battery voltage SVB1, adjusting it to become the changed total battery voltage SVBd equal to the reference total battery voltage SVBr (SVBd = SVBr).

[0092] In the method of this embodiment 3, by employing the load change process S33, it is possible to change the component voltage VBB of battery 1 independently of charging and discharging battery 1, and adjust the changed total component voltage SVBBd of multiple series-connected batteries 1. Therefore, it is easy to obtain a series battery pack in which the changed total battery voltage SVBd in the open-circuit state is adjusted to be equal to the reference total battery voltage SVBr.

[0093] The present invention has been described above in conjunction with embodiments 1, 2, and 3 and variations 1 and 2. However, the present invention is not limited to the embodiments described above, and it is obvious that appropriate modifications can be made to apply it without departing from its spirit.

[0094] For example, in Embodiment 1 and Modification 1, the self-discharge inspection steps of the battery 1, as shown in the initial battery voltage measurement step S7 to the judgment step S12, are performed during the manufacturing process of the battery 1. Therefore, these inspection steps can also be applied to the self-discharge inspection of batteries 1 that have already been put into use on the market.

[0095] Furthermore, in variation 1, the load BL applied to battery 1 during the load change process is changed, thereby changing the component voltage VBB of battery 1, so that the power supply current IP flowing through battery 1 matches the reference power supply current IPr. In addition, it can be applied to other scenarios where batteries (energy storage devices) are manufactured or their characteristics are measured, such as when battery 1 is subjected to CCCV charging or CV charging. At the end of the charging process, the load BL applied to battery 1 is increased, causing the component voltage VBB of battery 1 to rise slightly, accelerating the convergence of the charging current and stopping charging earlier.

Claims

1. A method for adjusting the device voltage of an energy storage device (1), which is a method for adjusting the device voltage (VB) of the energy storage device (1), wherein, When the energy storage device (1) is represented by an equivalent circuit (Ec) formed by connecting the capacitive device component (1B) and the short-circuit resistance (Rp) representing the magnitude of the self-discharge of the device component (1B) in parallel (Pc) with the DC resistance (Rs) of the energy storage device (1) in series, The aforementioned energy storage device (1) has the following characteristics: when pressed by a load (BL) and the device component (1B) is charged and generates a component voltage (VBB), the component voltage (VBB) decreases when the load (BL) decreases, and increases when the load (BL) increases. The above-mentioned device voltage adjustment method includes a component voltage change step utilizing load change. In this component voltage change step utilizing load change, the load (BL) applied to the above-mentioned energy storage device (1) which is pressed by a first load (BL1) and generates a first component voltage (VBB1) in the above-mentioned device component (1B) is changed from the first load (BL1), thereby causing the component voltage (VBB) to change from the first component voltage (VBB1).

2. The device voltage adjustment method for the energy storage device (1) according to claim 1, wherein, Before the above-mentioned component voltage change process utilizing load change, there is also a component voltage detection process (S7) for detecting the first component voltage (VBB1) of the above-mentioned energy storage device (1) pressed by the first load (BL1). The above-mentioned load change component voltage change process is a load change reference voltage conversion process that makes the load (BL) applied to the above-mentioned energy storage device (1) change so that the changed component voltage (VBBa) after the load change is equal to the reference component voltage (VBBr).

3. The device voltage adjustment method for the energy storage device (1) according to claim 1, wherein, Regarding the aforementioned energy storage device (1), it includes multiple energy storage devices (1). Prior to the above-mentioned component voltage change process utilizing load change, there is also a multiple component voltage detection process (S22) for detecting the first component voltage (VBB1) of the multiple energy storage devices (1) pressed by the first load (BL1). When the first component voltage (VBB1) generated by the reference energy storage device (1r) selected from the plurality of energy storage devices (1) is set as the reference first component voltage (VBB1r), and the energy storage device (1) other than the reference energy storage device (1r) whose first component voltage (VBB1) is different from the reference first component voltage (VBB1r) is set as the energy storage device to be adjusted (1c), The aforementioned component voltage change process utilizing load variation is a component voltage homogenization process that makes the changed component voltage (VBBa) after the load (BL) applied to the adjusted energy storage device (1c) change equal to the aforementioned reference first component voltage (VBB1r).

4. The device voltage adjustment method for the energy storage device (1) according to claim 1, wherein, Regarding the aforementioned energy storage device (1), it includes multiple energy storage devices (1). The above-mentioned load change component voltage change process is a load change reference total voltage conversion process that makes the total component voltage (SVBB) obtained by adding up all the component voltages (VBB) of the above-mentioned multiple energy storage devices (1) equal to the reference total component voltage (SVBBr).

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