Charge control device, power storage device, and charge control method

Abstract

To suppress rapid deterioration of a power storage element.SOLUTION: The charge control device changes a charge current value in a process of charging the energy storage device, charges the energy storage device so that the charge current value is minimized at the end of charging, calculates a charged electric quantity from a change point at which the charge current value changes to the end of charging, and changes a next charge condition when the calculated charged electric quantity is equal to or larger than a predetermined threshold.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a charge control device, a power storage device, and a charge control method. [Background technology]

[0002] CCCV charging is a known method for charging storage elements. CCCV charging is a method in which a storage element is charged with a constant current until its voltage reaches a CV voltage, and then the secondary battery is charged with a constant voltage. Patent Document 1 listed below describes that when switching from CC charging to CV charging, a period is provided between CC charging and CV charging in which charging is performed while the charging current is reduced, with the aim of accurately matching the voltage of the storage element to the CV voltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5525862 Summary of the Invention [Problem to be solved by the invention]

[0004] In energy storage devices such as lithium-ion secondary batteries, for example, charging at low temperatures or with a large charging current can cause a decrease in the negative electrode potential during charging, leading to the deposition of metals such as lithium on the negative electrode. This phenomenon of metal deposition in energy storage devices is called electrodeposition. Repeated electrodeposition is known to rapidly deteriorate the capacity of the energy storage device.

[0005] The present disclosure was completed in light of the above circumstances, and aims to suppress rapid deterioration of the capacity of an energy storage element. As a result of detailed investigation into the charging characteristics of an energy storage element, the present inventors have discovered that rapid deterioration of the capacity of an energy storage element can be suppressed by focusing on the amount of charged electricity. [Means for solving the problem]

[0006] The charging control device disclosed herein is a charging control device that controls the charging of a storage element, changes the charging current value during the charging process of the storage element, charges the storage element so that the charging current value is minimized at the end of charging, calculates the amount of charging electricity from the point at which the charging current value changes to the end of charging, and changes the next charging conditions if the calculated amount of charging electricity is equal to or greater than a predetermined threshold. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to suppress rapid deterioration of the capacity of the energy storage element. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating an electrical configuration of a battery and a charging device according to the embodiment. [Figure 2] FIG. [Figure 3] FIG. 10 is a diagram showing changes in charging current and cell voltage during CCCV charging. [Figure 4] FIG. 10 is a diagram showing changes in charging current and cell voltage during multi-stage constant current charging. [Figure 5] FIG. 10 is a diagram showing the correlation between the charged quantity of electricity and the negative electrode potential at the change point. [Figure 6] 4 is a flowchart showing a process in which the charge control device controls charging of the storage element. [Figure 7] FIG. 10 is a diagram showing the charging characteristics of a storage element. [Figure 8] FIG. 10 is a diagram showing an OCP table for a positive electrode. [Figure 9] FIG. 10 is a diagram showing the correspondence relationship between the CCP of the positive electrode and the OCP table of the positive electrode. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Outline of this embodiment) [1] The charge control device disclosed herein is a charge control device that controls the charging of a storage element, changes the charging current value during the charging process of the storage element, charges the storage element so that the charging current value is minimized at the end of charging, calculates the amount of charging electricity from the point at which the charging current value changes to the end of charging, and changes the next charging conditions if the calculated amount of charging electricity is equal to or greater than a predetermined threshold.

[0010] The inventors investigated the correlation between the deterioration state of the storage element and the amount of charged electricity from the change point of the charging current value to the end of charging, and found that the capacity of the storage element begins to deteriorate rapidly when the amount of charged electricity exceeds a predetermined threshold. Therefore, with the above configuration, when the amount of charged electricity is equal to or greater than a predetermined threshold, it is possible to determine that there is a sign of rapid capacity deterioration. Then, when a sign of rapid capacity deterioration is detected, the rapid capacity deterioration can be suppressed by changing the next charging conditions.

[0011] [2] In the above [1], the threshold value is preferably a value when the closed circuit potential of the negative electrode of the storage element at the change point is estimated to be a predetermined reference value.

[0012] With this configuration, it is possible to set a threshold value that increases the possibility of electrodeposition occurring at the change point, thereby preventing rapid deterioration of the capacity of the energy storage element due to repeated electrodeposition.

[0013] [3] The power storage device of the present disclosure includes a power storage element and the charge control device described in [1] or [2] above.

[0014] [4] The charging control method disclosed herein is a charging control method for controlling the charging of a storage element, which changes a charging current value during the charging process of the storage element, charges the storage element so that the charging current value is minimized at the end of charging, calculates the amount of charging electricity from the point at which the charging current value changes to the end of charging, and changes the next charging conditions if the calculated amount of charging electricity is equal to or greater than a predetermined threshold.

[0015] According to this charging control method, when the amount of charged electricity is equal to or greater than a predetermined threshold, it is determined that there is a sign of a sudden deterioration in the capacity of the storage element, and the next charging conditions can be changed, thereby suppressing a sudden deterioration in the capacity of the storage element.

[0016] <Embodiment> (Configuration of battery 50 and charging device 10) An embodiment of the present disclosure will be described with reference to FIGS. 1 to 9. FIG. 1 is a block diagram showing the electrical configuration of a battery 50 and a charging device 10. The battery 50 includes a current interruption device 53, a battery pack 60 consisting of a plurality of battery cells 62, a current measurement resistor 54, a management device 100, and a temperature sensor 115. The battery 50 is an example of an energy storage device of the present disclosure. The battery cells 62 are an example of energy storage elements of the present disclosure. The battery cells 62 are, for example, lithium-ion secondary batteries.

[0017] The current interruption device 53, current measurement resistor 54, and battery pack 60 are connected in series via power lines 55P and 55N. The power line 55P connects the positive external terminal 51 to the positive electrode of the battery pack 60. The power line 55N connects the negative external terminal 52 to the negative electrode of the battery pack 60. The current interruption device 53 and current measurement resistor 54 are located on the positive electrode side of the battery pack 60 and are provided on the positive electrode side power line 55P.

[0018] The current interruption device 53 is configured by a contact switch (mechanical type) such as a relay or a semiconductor switch such as an FET. By opening the current interruption device 53, the current of the battery 50 can be interrupted.

[0019] The current measuring resistor 54 generates a voltage according to the current of the battery pack 60. Discharge and charge can be determined from the polarity (positive or negative) of the voltage across the current measuring resistor 54. The temperature sensor 115 is of a contact or non-contact type and measures the temperature of the battery pack 60.

[0020] The management device 100 is provided on the circuit board unit 65. The management device 100 includes a voltage detection circuit 110, a processing unit 120, and a power supply circuit 130. The voltage detection circuit 110 is connected to both ends of each battery cell 62 via a signal line, and measures the cell voltage of each battery cell 62 and the total voltage of the assembled battery 60. The total voltage of the assembled battery 60 is the sum of the voltages of the multiple battery cells 62 connected in series.

[0021] The processing unit 120 includes a CPU 121 with a calculation function and a memory 123 serving as a storage unit. The processing unit 120 monitors the current of the assembled battery 60, the voltage of each battery cell 62, and the total voltage and temperature of the assembled battery 60 from the outputs of the current measurement resistor 54, the voltage detection circuit 110, and the temperature sensor 115. The processing unit 120 has a function of controlling charging of the battery 50. The management device 100 is an example of a charging control device of the present disclosure.

[0022] The memory 123 is a non-volatile storage medium such as a flash memory, an EEPROM, etc. The memory 123 stores a monitoring program for monitoring the state of the battery pack 60 and data required for executing the monitoring program.

[0023] The memory 123 stores a charge control program for controlling the charging of the battery cells 62 and data required for executing the charge control program (such as a threshold value for the amount of charged electricity, which will be described later). The charge control program can be written to a recording medium such as a CD-ROM.

[0024] Charging device 10 includes current detection resistor 11, charging circuit 13, and CPU 15, and is connected to external terminals 51 and 52 of battery 50. CPU 15 controls the magnitude of the charging current via charging circuit 13. Current detection resistor 11 is provided to detect the charging current.

[0025] As shown in FIG. 2, the battery 50 includes a housing 71. The housing 71 includes a main body 73 and a lid 74 made of a synthetic resin material. The main body 73 is cylindrical and has a bottom. The main body 73 includes a bottom portion 75 and four side portions 76. The four side portions 76 form an upper opening 77 at the top end.

[0026] The housing 71 houses the battery pack 60 and the circuit board unit 65. The battery pack 60 has a plurality of battery cells 62. The battery cells 62 may be lithium-ion secondary battery cells. The circuit board unit 65 is disposed on top of the battery pack 60.

[0027] The lid 74 closes the upper opening 77 of the main body 73. An outer peripheral wall 78 is provided around the periphery of the lid 74. The lid 74 has a protruding portion 79 that is generally T-shaped in plan view. The positive electrode external terminal 51 is fixed to one corner of the front of the lid 74, and the negative electrode external terminal 52 is fixed to the other corner.

[0028] 6, the management device 100 of this embodiment executes a charging process (S1), a calculation process (S2) for calculating the amount of charged electricity, which will be described later, and a determination process (S3) for determining whether the amount of charged electricity is equal to or greater than a predetermined threshold. If the amount of charged electricity is equal to or greater than the predetermined threshold, the management device 100 executes a condition change process (S5) for changing the next charging condition of the battery cell 62.

[0029] (Charging process) In the charging process, the charging device 10 charges the battery cells 62 under the command of the processing unit 120. The processing unit 120 changes the charging current value during the charging process of the battery cells 62. The processing unit 120 then gradually reduces the charging current value, and controls the charging of the battery cells 62 so that the charging current value is minimized when charging is completed. Furthermore, the charging of the battery cells 62 is controlled so that the voltage of the battery cells 62 reaches a predetermined upper limit voltage when charging is completed.

[0030] In the charging process, CCCV charging shown in Fig. 3 may be performed. CCCV charging is performed when the voltage of the battery cell 62 reaches an upper limit voltage V maxuntil a constant current I C (CC charging), and then the upper limit voltage V max This is a method of constant voltage charging (CV charging) of the battery cell 62. CCCV charging has a change point where the charging current value changes discontinuously at the timing when CC charging switches to CV charging. After the change point, the upper limit voltage V max The charging current is gradually reduced so as to maintain the voltage at the change point. It is known that electrodeposition is likely to occur in the battery cell 62 at the change point because the voltage is high and the charging current is large.

[0031] The charging process may also be multi-stage constant current charging. Multi-stage constant current charging is a method of gradually reducing the charging current of CC charging in multiple stages. For example, the multi-stage constant current charging shown in FIG. 4 includes two-stage CC charging and CV charging performed after CC charging. In two-stage CC charging, the voltage of the battery cell is increased to an upper limit voltage V max Lower switching voltage V step until a constant current I C1 Charging is then performed at a smaller constant current I C2 The battery cell voltage reaches the upper limit voltage V max Charging is continued until the charging current reaches . The CC charging of the multi-stage constant current charging may have three or more stages. In addition to the change point (second change point) where CC charging switches to CV charging, multi-stage constant current charging has a first change point where the charging current changes discontinuously in CC charging. In other words, multi-stage constant current charging includes multiple change points.

[0032] (Calculation process) In the calculation process, the processing unit 120 calculates the amount of charged electricity after the charging process. The amount of charged electricity is defined as the amount of electricity given to the battery cell 62 from the charging device 10 from the change point to the end of charging in the charging process.

[0033] For example, as shown in Fig. 3, when the charging process is performed by CCCV charging, the charged amount of electricity is the amount of electricity provided to the battery cell 62 during the period T. In other words, the charged amount of electricity is the amount of electricity provided to the battery cell 62 during CV charging.

[0034] Furthermore, as shown in FIG. 4, when the charging process is performed by multi-stage constant current charging, the charging quantity of electricity is the quantity of electricity provided to the battery cell 62 during period T1 or period T2. Because multi-stage constant current charging includes multiple change points, multiple charging quantities of electricity can be calculated. In such a case, any one of the charging quantities of electricity may be used in the subsequent process, or two or more may be used. When two or more charging quantities of electricity are used, the subsequent process will be performed for each charging quantity of electricity.

[0035] For simplicity, the following description of each process will be given on the assumption that the charging process is performed by CCCV charging.

[0036] (Correlation between the amount of charged electricity and the rapid deterioration of capacity) The inventors have investigated the charging characteristics of the battery cell 62 in detail and found that the capacity of the battery cell 62 after its lifespan is smaller and the amount of charged electricity is larger than that of the battery cell 62 immediately after manufacture. The inventors then plotted the amount of charged electricity against the number of charge / discharge cycles of the battery cell 62, and found that, as shown in the upper graph of FIG. 5, the amount of charged electricity is smaller at a predetermined number of cycles N th After that, we found that the amount of charge electricity rose significantly. Also, this cycle number N th It has been confirmed that the capacity of the battery cell 62 drops significantly after this number of cycles N th It was suggested that the subsequent rapid deterioration of capacity was due to electrodeposition. th The amount of charge in the threshold Q th and monitor the amount of charged electricity each time the charging process is completed, it is believed that it is possible to detect signs of rapid deterioration in the capacity of the battery cell 62.

[0037] (Determination process) In the determination process, the amount of charged electricity is equal to or exceeds a predetermined threshold Q th It is determined whether the threshold Q is equal to or greater than the threshold Q. th is stored in advance in the memory 123. thmay be determined experimentally. As will be described later, the threshold Q th may be determined from the relationship between the negative electrode potential and the charged quantity of electricity at the change point.

[0038] (Condition change processing) The amount of charge reaches a predetermined threshold Q th If the value is equal to or greater than this (S3: YES), it is determined that there is a sign of rapid capacity degradation (S4). Then, the processing unit 120 executes a condition change process (S5) to change the next charging conditions, thereby suppressing the occurrence of electrodeposition during the next charging. In the condition change process, the charging conditions are changed to those that make it even less likely for electrodeposition to occur. Specifically, the charging current value and the upper limit voltage are reduced, for example.

[0039] The amount of charge reaches a predetermined threshold Q th If the difference is less than 0.0 (S3: NO), it is determined that there is no sign of rapid capacity degradation (S6). In this case, the next charging conditions are not changed. This completes the charging control process for the battery cell 62 in this embodiment.

[0040] Similarly to the above, the charge control method of this embodiment includes a charging step of changing the charging current value during the charging of the battery cell 62 and charging the battery cell 62 so that the charging current value is minimized at the end of charging, a calculation step of calculating the amount of charged electricity from the change point at which the charging current value changes until the end of charging, and a step of calculating the amount of charged electricity by comparing the calculated amount of charged electricity with a predetermined threshold Q th The charge control method of this embodiment includes a determination step of determining whether the amount of charged electricity is equal to or greater than a predetermined threshold Q th If the above conditions are met, the method further includes a condition changing step of changing the next charging condition.

[0041] (Regarding the negative electrode potential at the change point) As described above, at the transition point, the negative electrode potential is particularly likely to decrease, making electrodeposition more likely to occur. For example, if the battery cell 62 is a lithium-ion secondary battery, deposition of metallic lithium, i.e., electrodeposition, may occur if the negative electrode potential (more specifically, the closed circuit potential) becomes 0 V or less relative to the potential of metallic lithium. Therefore, if the magnitude of the negative electrode potential at the transition point is a positive value close to 0 V, it can be determined that there is a sign of a rapid deterioration in the capacity of the battery cell 62.

[0042] Below, the amount of charge is the threshold Q th This means that the magnitude of the negative electrode potential at the change point is a predetermined reference value E th This is essentially the same as the following: First, we derive the correlation between the charged quantity of electricity and the negative electrode potential at the change point.

[0043] When the battery cell 62 is charged by CCCV charging, the charging characteristics shown in Figure 7 are obtained. The upper graph in Figure 7 shows the positive electrode potential during the charging process, more specifically the closed circuit potential (CCP) of the positive electrode. The middle graph in Figure 7 shows the negative electrode potential during the charging process, more specifically the CCP of the negative electrode. The lower graph in Figure 7 shows the cell voltage during the charging process, more specifically the closed circuit voltage (CCV).

[0044] Here, the CCP of the positive electrode and the CCP of the negative electrode are the potentials of the positive electrode and the negative electrode of the battery cell 62 when the battery cell 62 is electrically connected to an external circuit (charging circuit 13) and current is flowing (a load is applied between the positive electrode and the negative electrode). Also, the CCV is the cell voltage in the same state, and is the potential difference between the CCP of the positive electrode and the CCP of the negative electrode. In other words, the CCV, the CCP of the positive electrode, and the CCP of the negative electrode are respectively referred to as V C , E CP , and E CN Then, the following equation (1) holds:

[0045] V C =E CP -E CN (1)

[0046] The horizontal axis of the graph in Fig. 7 represents the amount of electricity given to the battery cell 62 from the charging device 10 during the charging process. E , the amount of electricity at the change point (i.e., when switching from CC charging to CV charging) is Q E -Q1. In other words, the amount of charge is Q1.

[0047] 8 shows a positive electrode open circuit potential (OCP) table. The positive electrode OCP table is data showing the relationship between the positive electrode OCP and the capacity (in the same unit as the quantity of electricity) of the battery cell 62, and is obtained in advance through experiments. Here, the positive electrode OCP is the potential of the positive electrode of the battery cell 62 when the battery cell 62 is electrically disconnected from the external circuit (i.e., no load is applied between the positive and negative electrodes).

[0048] It is known that the CCP of the positive electrode is equal to the sum of the OCP of the positive electrode and the amount of positive polarization. OP and P P Then, the following equation (2) holds:

[0049] E CP =E OP +P P (2)

[0050] Here, the amount of positive electrode polarization is an amount mainly caused by polarization due to a charge transfer reaction, and can be measured, for example, in a bipolar cell using a positive electrode as the working electrode and lithium metal as the counter electrode. The amount of positive electrode polarization depends on the charging current and the temperature of the battery cell 62. When a charging current is flowing, the amount of positive electrode polarization takes a positive value. The larger the charging current, the larger the amount of positive electrode polarization tends to be. The lower the temperature of the battery cell 62, the larger the amount of positive electrode polarization tends to be. A table can also be prepared in advance for the amount of positive electrode polarization according to temperature and charging current value.

[0051] Next, the positive electrode OCP at the change point is derived from the graph of the positive electrode CCP shown in the upper part of Figure 7 and the positive electrode OCP table. Figure 9 is a graph that enlarges the CV charging region of the graph in the upper part of Figure 7, and the positive electrode CCP is shown by the solid line. At the end of charging, the quantity of electricity is Q E and the CCP of the positive electrode is E1. Also, at the change point, the quantity of electricity is Q E -Q1 and the positive CCP is E2.

[0052] The graph in Fig. 9 also has an OCP table for the positive electrode (broken line) superimposed on it. Here, as shown in Fig. 8, the OCP table for the positive electrode is a table for the capacity of the battery cell 62, and is not a table for the amount of electricity. Therefore, we will approximate that the OCP for the positive electrode and the CCP for the positive electrode are equal at the end of charging, and will convert the horizontal axis in Fig. 9. Strictly speaking, as expressed in equation (2), the CCP for the positive electrode is the sum of the OCP for the positive electrode and the amount of positive electrode polarization. However, because the charging current is at a minimum at the end of charging, the amount of positive electrode polarization is considered to be sufficiently small compared to the OCP for the positive electrode.

[0053] From FIG. 8, the capacity at which the positive electrode OCP is E1, that is, the CCP value of the positive electrode at the end of charging (see FIG. 9), is C1. Therefore, as shown in FIG. 9, the capacity C1 is the quantity of electricity Q E The horizontal axis of the positive OCP table is offset to correspond to the above. Then, the positive OCP at the change point is the value when the capacitance becomes C1-Q1, which is E3 (see Figures 8 and 9). Here, the positive OCP table is calculated using the function E OP If we consider this, the positive OCP (i.e., E3) at the change point is E OP (Q E -Q1) (see Figure 9). Similarly, the CCP of the positive electrode can be expressed as a function E CP If we consider this, the positive CCP at the change point (i.e., E2) is E CP (Q E -Q1).

[0054] In addition, if we consider equation (1) as a function of the electrical quantity, QE By substituting -Q1, the following relational expression (3) holds true.

[0055] V C (Q E -Q1)=E CP (Q E -Q1)-E CN (Q E -Q1) (3)

[0056] In equation (3), E CN (Q E -Q1) is the negative CCP at the change point. V C (Q E -Q1) is the CCV at the change point, so the upper limit voltage V max (See the lower graph in Figure 7). That is, the following equation (4) holds true.

[0057] V C (Q E -Q1)=V max (4)

[0058] In addition, if we consider equation (2) as a function of the electrical quantity, Q E By substituting -Q1, the following relational expression (5) holds.

[0059] E CP (Q E -Q1)=E OP (Q E -Q1)+P P (Q E -Q1) (5)

[0060] From formulas (3), (4), and (5), the CCP of the negative electrode at the change point is expressed by the following formula (6).

[0061] E CN (Q E -Q1)=E OP (Q E -Q1)+P P (Q E -Q1)-V max (6)

[0062] In equation (6), V max is a constant. P P (Q E -Q1) is the amount of polarization of the positive electrode, which is greatly affected by temperature and charging current, but is not so greatly affected by the amount of electricity. OP (Q E -Q1) is the OCP of the positive electrode at the change point. As shown in Figure 9, the OCP of the positive electrode is highly dependent on the amount of electricity. In detail, the OCP of the positive electrode tends to increase as the amount of electricity increases. Therefore, E OP (Q E -Q1) is a term that is highly dependent on the amount of charge Q1. Therefore, E CN (Q E -Q1), that is, the CCP of the negative electrode at the change point, can be regarded as a function of the charge quantity of electricity Q1. Equation (6) expresses the correlation between the charge quantity of electricity Q1 and the CCP of the negative electrode at the change point. In detail, as the charge quantity of electricity Q1 increases, the CCP of the negative electrode at the change point tends to decrease.

[0063] As described above, for example, by using the charging characteristics of the battery cell 62, the positive electrode OCP table, and the positive electrode polarization amount table, it is possible to determine the correlation between the charged electrical quantity and the negative electrode CCP at the change point.

[0064] The graph in the lower part of Figure 5 shows the CCP of the negative electrode at the change point, estimated from the charge quantity (shown in the upper graph of Figure 5) using equation (6). The vertical axis of the graph in the lower part of Figure 5 is based on the potential of metallic lithium. In other words, the unit of the vertical axis is V vs. Li / Li + is.

[0065] The CCP of the negative electrode at the change point is the number of cycles N at which the charge quantity rises. th The reference value E is slightly greater than 0V. th Take the number of cycles N th This means that the rate of increase in the charge quantity becomes negative and decreases rapidly after that. thThis indicates that electrodeposition occurs significantly in the subsequent region, causing a rapid deterioration in the capacity of the battery cell 62. From this correspondence, it can be seen that by focusing on the charged amount of electricity, it is possible to detect signs of a rapid deterioration in the capacity of the battery cell 62.

[0066] Also, using equation (6), the reference value E of the CCP of the negative electrode at the change point th By appropriately setting the threshold value Q th In order to detect a sign of rapid deterioration in the capacity of the battery cell 62 using the charge control device (management device 100) or charge control method of this embodiment, the reference value E th It is preferable that the reference value E is slightly larger than the value at which electrodeposition begins to occur. th can be set to a value slightly greater than 0 V based on the potential of metallic lithium. At low temperatures, even if the CCP of the negative electrode at the change point falls below 0 V, electrodeposition may not occur. This is because the amount of negative electrode polarization increases as the temperature drops. Therefore, depending on the temperature, a value below 0 V may be set as the reference value. Therefore, the reference value E th It is preferable that a plurality of values ​​are set for each temperature.

[0067] Reference value E th From the threshold Q th When determining the threshold Q, the formula (6) may be optimized using the positive electrode OCP table and the positive electrode polarization amount table when the capacity is deteriorated. th Since is a quantity that depends on the ease of electrodeposition, it also varies greatly depending on the temperature and upper limit voltage. th It is preferable that a plurality of values ​​are set for each temperature and each upper limit voltage.

[0068] According to this embodiment, the charge control device (management device 100) and the charge device 10 do not need to measure or estimate the CCP of the negative electrode, and the charge amount and the predetermined threshold Q th Based on the magnitude relationship between the voltage Vcc and the capacity Vcc, it is possible to easily detect signs of rapid deterioration in the capacity of the battery cell 62.

[0069] (Effects of the embodiment) The charge control device (management device 100) of this embodiment controls the charging of the storage element (battery cell 62). The charge control device changes the charging current value during the charging process of the storage element, charges the storage element so that the charging current value is minimized at the end of charging, calculates the amount of charged electricity from the point at which the charging current value changes until the end of charging, and checks whether the calculated amount of charged electricity is greater than or equal to a predetermined threshold Q th If the condition is equal to or greater than this, the next charging conditions are changed.

[0070] According to the above configuration, the amount of charged electricity is equal to or exceeds a predetermined threshold Q th If the above condition is met, it can be determined that there is a sign of rapid capacity degradation. If a sign of rapid capacity degradation is detected, the rapid capacity degradation can be suppressed by changing the next charging conditions.

[0071] In this embodiment, the threshold Q th is the value at which the closed circuit potential of the negative electrode of the storage element at the change point is equal to a predetermined reference value E th It is preferable that the value be a value when it is estimated that the value is .

[0072] With this configuration, the threshold Q th Therefore, it is possible to suppress a rapid deterioration in the capacity of the electricity storage element due to repeated occurrence of electrodeposition.

[0073] <Other embodiments> The present disclosure is not limited to the embodiments described above and illustrated in the drawings, but is intended to include all modifications within the scope and meaning equivalent to the claims. The technical scope of the present disclosure also includes, for example, the following embodiments.

[0074] In the embodiment, a battery cell 62 is shown as an example of an energy storage element. The energy storage element may be a capacitor. The battery cell is not limited to a lithium-ion secondary battery cell, but may be other secondary battery cells such as a lead-acid battery cell, a nickel-metal hydride battery cell, or a lithium-air battery cell. The energy storage element is not limited to a case where a plurality of elements are connected in series or series-parallel, and may be configured as a single cell.

[0075] The present technology can be applied to a charging control program for a power storage device. The charging control program for a power storage device is a program that causes a computer to execute a charging control method according to an embodiment. The present technology can also be applied to a recording medium on which the charging control program for a power storage device is recorded. The computer is, for example, the processing unit 120. [Explanation of symbols]

[0076] 10:Charging device 50: Battery (electricity storage device) 60: Battery pack 62: Battery cell (energy storage element) 100: Management device (charging control device) 120: Processing section E th :Reference value Q th :Threshold

Claims

1. A charge control device that controls charging of a storage element, changing a charging current value during the charging of the storage element, and charging the storage element so that the charging current value becomes a minimum at the end of charging; Calculating the amount of charge electricity from the change point at which the charging current value changes until the end of charging; A charge control device that changes the next charging condition when the calculated charged amount of electricity is equal to or greater than a predetermined threshold.

2. 2. The charge control device according to claim 1, wherein the threshold value is a value when the closed circuit potential of the negative electrode of the storage element at the change point is estimated to be a predetermined reference value.

3. A storage element; A power storage device comprising: the charge control device according to claim 1 or 2.

4. A charge control method for controlling charging of a storage element, comprising: changing a charging current value during the charging of the storage element, and charging the storage element so that the charging current value becomes a minimum at the end of charging; Calculating the amount of charge electricity from the change point at which the charging current value changes until the end of charging; A charging control method, wherein when the calculated amount of charged electricity is equal to or greater than a predetermined threshold, the next charging conditions are changed.

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