Charge control method for zinc secondary battery, charge control device for zinc secondary battery, and charge control system for zinc secondary battery

Abstract

This charge control method for a zinc secondary battery includes: a charging rate measurement step for measuring a charging rate of the zinc secondary battery after charging is started; a first determination step for determining whether or not the charging rate measured in the charging rate measurement step is increased by a predetermined percentage as compared with a charging rate before starting measurement; an open circuit voltage measurement step for measuring an open circuit voltage value of the zinc secondary battery when determination is made that the charging rate measured in the first determination step has increased by the predetermined percentage; a difference calculation step for calculating a difference between the open circuit voltage value measured in the open circuit voltage measurement step and a predetermined ideal open circuit voltage value; a second determination step for determining whether or not the difference calculated by the difference calculation step is equal to or greater than a predetermined value; and an oxygen generation suppression control execution step for executing oxygen generation suppression control for suppressing generation of oxygen during charging when determination is made that the difference is equal to or greater than the predetermined value in the second determination step.

Description

Zinc secondary battery charge control method, zinc secondary battery charge control device, and zinc secondary battery charge control system

[0001] The present disclosure relates to a method for controlling charging of a zinc secondary battery, a charge control device for a zinc secondary battery, and a charge control system for a zinc secondary battery. This application claims priority to Japanese Application No. 2024-031851, filed on March 4, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Techniques relating to the control of battery charging and discharging are disclosed, for example, in WO2021 / 192382 (Patent Document 1) and WO2023 / 139921 (Patent Document 2).

[0003] WO2021 / 192382WO2023 / 139921

[0004] For zinc secondary batteries, it is required to suppress deterioration of battery performance while performing efficient charging during charging. Therefore, one of the objects is to provide a charging control method for zinc secondary batteries that can suppress deterioration of battery performance while performing efficient charging.

[0005] A charging control method for a zinc secondary battery according to the present disclosure controls charging of the zinc secondary battery. The charging control method for a zinc secondary battery includes: a receiving step of receiving an instruction to start charging the zinc secondary battery; a charging rate measurement step of measuring the charging rate of the zinc secondary battery after starting charging if the instruction to start charging is received in the receiving step; a first determination step of determining whether the charging rate measured in the charging rate measurement step has increased by a predetermined percentage compared to the charging rate before starting measurement; an open-circuit voltage measurement step of interrupting charging and measuring an open-circuit voltage value of the zinc secondary battery if it is determined in the first determination step that the charging rate measured has increased by the predetermined percentage; a difference calculation step of calculating a difference between the open-circuit voltage value measured in the open-circuit voltage measurement step and a predetermined ideal open-circuit voltage value; a second determination step of determining whether the difference calculated in the difference calculation step is equal to or greater than a predetermined value; an oxygen generation suppression control implementation step of implementing oxygen generation suppression control to suppress oxygen generation during charging if it is determined in the second determination step that the difference is equal to or greater than the predetermined value; and a charge resumption step of resuming charging after implementing the oxygen generation suppression control implementation step.

[0006] According to this charging control method for a zinc secondary battery, it is possible to suppress deterioration of battery performance while performing efficient charging.

[0007] Fig. 1 is a schematic diagram conceptually showing a part of a zinc secondary battery. Fig. 2 is a block diagram showing the configuration of a zinc secondary battery charge control system including a zinc secondary battery charge control device in embodiment 1 according to the present disclosure. Fig. 3 is a graph showing calibration curve data as ideal open-circuit voltage value data. Fig. 4 is a flowchart showing the process flow when charging a zinc secondary battery using the zinc secondary battery charge control system in embodiment 1. Fig. 5 is a graph showing an image of voltage transition during charging. Fig. 6 is a graph showing the relationship between actual electrode potential and charging rate in this embodiment.

[0008] [Outline of the embodiment] First, embodiments of the present disclosure will be listed and described. A charging control method for a zinc secondary battery according to the present disclosure controls charging of a zinc secondary battery. The charging control method for a zinc secondary battery includes: a receiving step of receiving an instruction to start charging the zinc secondary battery; a charging rate measurement step of measuring the charging rate of the zinc secondary battery after starting charging if the instruction to start charging is received in the receiving step; a first determination step of determining whether the charging rate measured in the charging rate measurement step has increased by a predetermined percentage compared to the charging rate before measurement was started; an open-circuit voltage measurement step of interrupting charging and measuring an open-circuit voltage value of the zinc secondary battery if it is determined in the first determination step that the charging rate measured has increased by the predetermined percentage; a difference calculation step of calculating the difference between the open-circuit voltage value measured in the open-circuit voltage measurement step and a predetermined ideal open-circuit voltage value; a second determination step of determining whether the difference calculated in the difference calculation step is equal to or greater than a predetermined value; an oxygen generation suppression control implementation step of implementing oxygen generation suppression control to suppress oxygen generation during charging if it is determined in the second determination step that the difference is equal to or greater than the predetermined value; and a charge resumption step of resuming charging after implementing the oxygen generation suppression control implementation step.

[0009] Zinc secondary batteries use nickel as the material for the positive electrode and zinc as the material for the negative electrode, and are repeatedly charged and discharged during use. Oxygen is generated at the positive electrode during charging or when the zinc secondary battery is idle. The inventors considered the following: If this oxygen generated at the positive electrode passes through the separator and migrates to the negative electrode, it can cause zinc oxide to form at the negative electrode and zinc to dissolve in the electrolyte, ultimately promoting deterioration of battery performance. Furthermore, oxygen generation at the positive electrode promotes expansion of the zinc secondary battery itself, and it is desirable to avoid this situation as much as possible. Regarding charging, for example, they found that while increasing the charging voltage enables charging in a short time, increasing the charging voltage also increases the likelihood of oxygen generation. While lowering the charging voltage and charging for a long period of time to minimize oxygen generation can suppress oxygen generation, this is insufficient from the perspective of efficient charging.

[0010] Theoretically, the amount of oxygen generated is correlated with the charge capacity, and it is thought that it is possible to predict the amount of oxygen generated in advance from the difference between the ideal value and the actual value.The inventors then came up with a method for controlling the charge of the zinc secondary battery having the above configuration.

[0011] According to the charging control method for a zinc secondary battery having the above configuration, when charging begins, the charging rate is measured, and the difference between the actual open-circuit voltage value and a predetermined ideal open-circuit voltage value is calculated according to the rate of increase of the charging rate. If the difference is equal to or greater than a predetermined value, oxygen generation suppression control is implemented to suppress oxygen generation. This suppresses oxygen generation on the positive electrode side during charging, thereby suppressing the generation of zinc oxide on the negative electrode side and the dissolution of zinc into the electrolyte. Furthermore, this reduces the risk of unnecessarily long charging times, enabling efficient charging. Therefore, the charging control method for a zinc secondary battery described above allows efficient charging while suppressing deterioration of battery performance.

[0012] In the charging control method for a zinc secondary battery of the above aspect, the charging rate measurement step, the first determination step, the open circuit voltage value measurement step, the difference calculation step, the second determination step, the oxygen generation suppression control execution step, and the charging restart step may be repeated at predetermined intervals. By doing so, it is possible to suppress deterioration of battery performance while performing efficient charging until charging is completed or until a predetermined charge amount is reached.

[0013] In the charging control method for a zinc secondary battery according to any one of the above aspects, the ideal open-circuit voltage value may include data on a calibration curve of the ideal open-circuit voltage value. This allows for highly accurate oxygen generation suppression control. Therefore, it is possible to further suppress deterioration of battery performance.

[0014] In the charging control method for a zinc secondary battery according to any one of the above aspects, the zinc secondary battery may be charged by constant voltage charging. The oxygen generation suppression control implementation step may include a step of lowering the voltage value in the constant voltage charging. With this configuration, oxygen generation can be more reliably suppressed by controlling the voltage value.

[0015] In the charging control method for a zinc secondary battery according to any one of the above aspects, the zinc secondary battery may be charged by constant current charging. The oxygen generation suppression control execution step may include a step of reducing the current value in the constant current charging. With this configuration, oxygen generation can be more reliably suppressed by controlling the current value.

[0016] In the charging control method for a zinc secondary battery according to any one of the above aspects, if the second determination step determines that the difference is less than a predetermined value, charging may be continued without implementing oxygen generation suppression control. By doing so, when the difference is determined to be less than the predetermined value, charging can be carried out smoothly. Therefore, more efficient charging is possible.

[0017] In the charging control method for a zinc secondary battery according to any one of the above aspects, the predetermined value may be 5 mV or more and 50 mV or less. By doing so, it is possible to perform efficient charging while more appropriately suppressing oxygen generation.

[0018] In the charging control method for a zinc secondary battery according to any one of the above aspects, the predetermined ratio may be 1% or more and 20% or less, thereby enabling efficient charging while more strictly suppressing oxygen generation.

[0019] In the charging control method for a zinc secondary battery according to any one of the above aspects, the predetermined timing may be 1 second or more and 300 seconds or less, thereby enabling efficient charging while suppressing the risk of a significant increase in charging time.

[0020] A charge control device for a zinc secondary battery according to the present disclosure controls charging of the zinc secondary battery. The charge control device for a zinc secondary battery includes: a receiving unit that receives an instruction to start charging the zinc secondary battery; a charging rate measurement unit that measures the charging rate of the zinc secondary battery after starting charging if the receiving unit receives the instruction to start charging; a first determination unit that determines whether the charging rate measured by the charging rate measurement unit has increased by a predetermined percentage compared to the charging rate before measurement started; an open-circuit voltage measurement unit that interrupts charging and measures an open-circuit voltage value of the zinc secondary battery if the first determination unit determines that the charging rate measured has increased by the predetermined percentage; a difference calculation unit that calculates a difference between the open-circuit voltage value measured by the open-circuit voltage measurement unit and a predetermined ideal open-circuit voltage value; a second determination unit that determines whether the difference calculated by the difference calculation unit is equal to or greater than a predetermined value; an oxygen generation suppression control implementation unit that implements oxygen generation suppression control to suppress oxygen generation during charging if the second determination unit determines that the difference is equal to or greater than the predetermined value; and a charge restart unit that restarts charging after implementing the oxygen generation suppression control implementation unit.

[0021] Such a charging control device for a zinc secondary battery can suppress deterioration of battery performance while carrying out efficient charging.

[0022] The charging control system for a zinc secondary battery of the present disclosure controls charging of a zinc secondary battery. a first determination unit that determines whether the charging rate measured by the charging rate measurement unit has increased by a predetermined percentage compared to the charging rate before measurement started; an open-circuit voltage measurement unit that interrupts charging and measures the open-circuit voltage value of the zinc secondary battery if the first determination unit determines that the charging rate measured has increased by the predetermined percentage; a difference calculation unit that calculates the difference between the open-circuit voltage value measured by the open-circuit voltage measurement unit and the ideal open-circuit voltage value stored in the memory unit; a second determination unit that determines whether the difference calculated by the difference calculation unit is equal to or greater than a predetermined value; an oxygen generation suppression control implementation unit that implements oxygen generation suppression control that suppresses oxygen generation during charging if the second determination unit determines that the difference is equal to or greater than the predetermined value; and a charge restart unit that restarts charging after implementing the oxygen generation suppression control implementation unit.

[0023] According to such a charging control system for a zinc secondary battery, it is possible to suppress deterioration of battery performance while carrying out efficient charging.

[0024] [Specific Example of Embodiment] Next, specific embodiments of the charging control method and charging control system for zinc secondary batteries of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and their description will not be repeated.

[0025] The present disclosure provides a method for controlling charging of a zinc secondary battery, a charging control device for a zinc secondary battery, and a charging control system for a zinc secondary battery. The charging control device and the charging control system for a zinc secondary battery perform control when charging a zinc secondary battery.

[0026] Fig. 1 is a schematic diagram conceptually showing a part of a zinc secondary battery. Referring to Fig. 1, the zinc secondary battery 11 includes a positive electrode 12 made of nickel, a negative electrode 13 made of zinc, an electrolyte 14 that fills the positive electrode 12 and the negative electrode 13, and a separator 15 that separates the positive electrode 12 side from the negative electrode 13 side in the electrolyte 14. During charging, oxygen 16 is generated on the positive electrode side due to the influence of water electrolysis, etc. The oxygen 16 molecules are conceptually shown enlarged to facilitate understanding. The generated oxygen 16 is indicated by an arrow F １ As shown by arrow F, the particles may leave the surface 17 of the electrolyte 14 as they are. ２ , arrow F ３ As shown by arrow F, the separator 15 passes through the electrolyte 14. ４ , arrow F ５ As shown in the figure, the oxygen may reach the negative electrode 13. If the oxygen reaches the negative electrode 13, the zinc, which is a constituent material of the negative electrode 13, may dissolve in the electrolyte 14 due to the oxygen cycle, or the oxygen 16 may combine with the zinc to produce zinc oxide (ZnO) 18. If this occurs, the amount of zinc available for charging and discharging will decrease, resulting in a deterioration of battery performance.

[0027] FIG. 2 is a block diagram showing the configuration of a zinc secondary battery charge control system including a zinc secondary battery charge control device according to a first embodiment of the present disclosure. Referring to FIG. 2 , the zinc secondary battery charge control system 20 includes a zinc secondary battery 11 and a zinc secondary battery charge control device 21 that controls charging of the zinc secondary battery 11. The charge control device 21 includes an interface unit 22 that exchanges data with the outside, a controller 23 that serves as a control unit that controls charging of the zinc secondary battery 11, and a storage device 24 that serves as a storage unit for storing data. Examples of the storage device 24 include a hard disk drive and nonvolatile memory. The storage device 24 stores data such as a predetermined ideal open-circuit voltage value during charging of the zinc secondary battery 11. Hereinafter, the open-circuit voltage may be abbreviated as OCV (Open Circuit Voltage). The charging rate may be abbreviated as SOC (State of Charge). Note that constant voltage charging may be abbreviated as CC (Constant Current) charging, and constant current charging may be abbreviated as CV (Constant Voltage) charging. The controller 23 includes a reception unit 31, a charging rate measurement unit 32, a first determination unit 33, an open circuit voltage measurement unit 34, a difference calculation unit 35, a second determination unit 36, an oxygen generation suppression control implementation unit 37, and a charge restart unit 38.

[0028] The receiving unit 31 receives an instruction to start charging the zinc secondary battery. When the receiving unit 31 receives the instruction to start charging, the charging rate measurement unit 32 measures the charging rate of the zinc secondary battery 11 after starting charging. The first determination unit 33 determines whether the charging rate measured by the charging rate measurement unit 32 has increased by a predetermined percentage compared to before measurement started. The open-circuit voltage measurement unit 34 measures the open-circuit voltage value of the zinc secondary battery 11 if the first determination unit 33 determines that the charging rate measured has increased by the predetermined percentage. The difference calculation unit 35 calculates the difference between the open-circuit voltage value measured by the open-circuit voltage measurement unit 34 and the ideal open-circuit voltage value stored in the storage device 24. The second determination unit 36 ​​determines whether the difference calculated by the difference calculation unit 35 is equal to or greater than a predetermined value. If the second determination unit 36 ​​determines that the difference is equal to or greater than the predetermined value, the oxygen generation suppression control implementation unit 37 implements oxygen generation suppression control to suppress oxygen generation during charging. The charging restart unit 38 restarts charging after executing the oxygen generation suppression control execution unit 37. The configuration of each unit will be described in detail later.

[0029] Here, the ideal OCV data stored in the storage device 24 will be described. FIG. 3 is a graph showing calibration curve data as ideal OCV data. In FIG. 3, the horizontal axis represents SOC (%), and the vertical axis represents electrode potential (V (volts)). Referring to FIG. 3, the graph of calibration curve 19 is created by starting charging at an early stage of the zinc secondary battery, i.e., when no charging or discharging has been performed, stopping charging every 10% SOC, and measuring the OCV for a time period between 10 seconds and 10 minutes, for example. The electrode potential values ​​for every 10% SOC are then plotted to create data for calibration curve 19. At a position where the SOC is close to 0%, the OCV increases somewhat rapidly, and then the OCV increases more gradually. At a position where the SOC is close to 100%, the OCV increases somewhat rapidly, similar to when the SOC is close to 0%. This data for calibration curve 19 is stored in the storage device 24. Then, the data of the calibration curve 19 stored at the stages of the difference calculation unit 35, the second determination unit 36, etc. are used.

[0030] Next, a description will be given of a zinc secondary battery charge control method performed using the zinc secondary battery charge control device 21 and the zinc secondary battery charge control system 20. Fig. 4 is a flowchart showing the flow of processing when charging the zinc secondary battery 11 using the zinc secondary battery charge control system 20 in embodiment 1.

[0031] 4, first, the reception unit 31 receives an instruction to start charging the zinc secondary battery 11 as a reception step (YES in step S11 in FIG. 4, hereinafter, "step" will be omitted). When the instruction to start charging is received, charging is started as a charge rate measurement step (S12), and the charge rate measurement unit 32 measures the charge rate of the zinc secondary battery (S13). Here, charging is performed by CV charging. Note that in S12, the start of second or subsequent charging, which is derived from the NO step in S19 described later, is a restart of charging.

[0032] In the first determination step, the first determination unit 33 determines whether the charging rate measured before the measurement has started has increased by a predetermined percentage, i.e., 10% in this embodiment (S14). If the first determination unit 33 determines that the charging rate has increased by 10% (YES in S14), the open-circuit voltage measurement unit 34 interrupts charging and measures the OCV (S15), in the open-circuit voltage measurement step. The OCV is measured under the same conditions as when the calibration curve data was created, for a predetermined time period ranging from 10 seconds to 10 minutes. Then, in the difference calculation step, the difference calculation unit 35 calculates the difference between the measured OCV and a predetermined ideal open-circuit voltage value (S16). The ideal open-circuit voltage value is stored in the storage device 24 as described above, and this value is used.

[0033] Thereafter, the second determination unit 36 ​​determines whether the difference calculated by the difference calculation unit 35 is equal to or greater than a predetermined value, in this embodiment, 5 mV or greater, as a second determination step (S17). If the second determination step determines that the difference is less than 5 mV (NO in S17), charging continues without implementing oxygen generation suppression control. That is, charging is resumed (S12). If the difference is equal to or greater than 5 mV (YES in S17), oxygen generation suppression control is implemented by the oxygen generation suppression control implementation unit 37 as an oxygen generation suppression control implementation step (S18). In this embodiment, this is implemented by controlling to lower the voltage value during CV charging.

[0034] FIG. 5 is a graph showing an image of the transition of voltage during charging. In FIG. 5, the horizontal axis represents SOC, and the vertical axis represents voltage. In the graph shown in FIG. 5, the solid line represents charging, and the dashed line represents a case where the OCV is measured and confirmed. First, by also referring to FIG. 5, the behavior during charging is roughly as shown in the graph. Then, it is determined whether the OCV deviates from the initial value when the OCV is confirmed. If the OCV has decreased, the voltage value is reduced in the case of CV charging. Note that the current value is reduced in the case of CC charging. Then, if the OCV does not return to a normal value, the charge capacity is corrected from the OCV value. Alternatively, the target value of the discharge capacity is changed.

[0035] 6 is a graph showing the relationship between the actual electrode potential and the SOC in this embodiment. In FIG. 6, the horizontal axis represents the SOC (%), and the vertical axis represents the electrode potential (V). In FIG. 6, the actual charging time is shown by line 25, and the data of the calibration curve 19 is also shown. Referring to FIG. 6, at point P １ As shown in the figure, when the OCV is abnormal, in this embodiment the difference is 5 mV, the actually charged SOC is calculated and the point P ２ If there is a difference between the SOC and the SOC during charging, the arrow D １ As shown in the graph, the CV charging voltage is lowered by, for example, 10 mV. The graph showing the result of the lowering is shown by line 26. This operation is repeated until the calibration curve OCV and the CV charging voltage have the same value.

[0036] After the oxygen generation suppression control execution unit has performed this control, charging is resumed as a charge restart step (NO in S19). That is, if NO in S19, the process returns to S12 and the same control is performed. Specifically, the charging rate measurement step, first determination step, open-circuit voltage value measurement step, difference calculation step, second determination step, oxygen generation suppression control execution step, and charge restart step are repeated at predetermined intervals. This is performed until charging is completed (YES in S19). That is, charging is continued until full charge is achieved or a predetermined charge amount is reached (YES in S19).

[0037] As described above, the charging control method for a zinc secondary battery 11 according to the present disclosure includes: a receiving step of receiving an instruction to start charging the zinc secondary battery 11; a charging rate measurement step of measuring the charging rate of the zinc secondary battery after starting charging if the instruction to start charging is received by the receiving step; a first determination step of determining whether the charging rate measured by the charging rate measurement step has increased by a predetermined percentage compared to the charging rate before the measurement was started; an open-circuit voltage measurement step of interrupting charging and measuring the open-circuit voltage value of the zinc secondary battery if it is determined by the first determination step that the charging rate measured has increased by the predetermined percentage; a difference calculation step of calculating the difference between the open-circuit voltage value measured by the open-circuit voltage measurement step and a predetermined ideal open-circuit voltage value; a second determination step of determining whether the difference calculated by the difference calculation step is equal to or greater than a predetermined value; an oxygen generation suppression control implementation step of implementing oxygen generation suppression control to suppress oxygen generation during charging if it is determined by the second determination step that the difference is equal to or greater than the predetermined value; and a charge resumption step of resuming charging after the oxygen generation suppression control implementation step.

[0038] According to the charging control method for the zinc secondary battery 11 configured as described above, when charging begins, the charging rate is measured, and the difference between the actual open-circuit voltage value and a predetermined ideal open-circuit voltage value is calculated according to the rate of increase of the charging rate. If the difference is equal to or greater than a predetermined value, oxygen generation suppression control is implemented to suppress oxygen generation. This suppresses oxygen generation on the positive electrode side during charging, thereby suppressing the generation of zinc oxide on the negative electrode side and the dissolution of zinc into the electrolyte. Furthermore, this reduces the risk of unnecessarily long charging times, enabling efficient charging. Therefore, the charging control method for the zinc secondary battery described above allows efficient charging while suppressing deterioration of battery performance.

[0039] In this embodiment, the charging rate measurement step, first determination step, open circuit voltage measurement step, difference calculation step, second determination step, oxygen generation suppression control execution step, and charging restart step are repeated at predetermined intervals, thereby suppressing deterioration of battery performance while performing efficient charging until charging is completed or a predetermined charge amount is reached.

[0040] In this embodiment, the ideal open-circuit voltage value includes data on a calibration curve of the ideal open-circuit voltage value. Therefore, oxygen generation suppression control can be performed with high accuracy. Therefore, deterioration of battery performance can be further suppressed.

[0041] In this embodiment, the zinc secondary battery is charged by constant voltage charging. The oxygen generation suppression control implementation step includes a step of lowering the voltage value during constant voltage charging. Therefore, by controlling the voltage value, oxygen generation can be more reliably suppressed.

[0042] In this embodiment, if the second determination step determines that the difference is less than the predetermined value, charging continues without implementing oxygen generation suppression control. Therefore, when it is determined that the difference is less than the predetermined value, charging can be carried out smoothly. Therefore, more efficient charging is possible.

[0043] In the above embodiment, the predetermined value may be 5 mV or more and 50 mV or less, which makes it possible to more appropriately suppress oxygen generation and to efficiently charge the battery.

[0044] In the above embodiment, the predetermined percentage may be 1% or more and 20% or less, which allows efficient charging while more strictly suppressing oxygen generation.

[0045] In the above embodiment, the predetermined timing may be between 1 second and 300 seconds, which allows efficient charging while minimizing the risk of a significant increase in charging time.

[0046] In the above embodiment, the zinc secondary battery may be charged by constant current charging. The oxygen generation suppression control step may include a step of reducing the current value during constant current charging. With this configuration, oxygen generation can be more reliably suppressed by controlling the current value.

[0047] It should be understood that the embodiments disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined not by the above meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0048] REFERENCE SIGNS LIST 11 Zinc secondary battery, 12 Positive electrode, 13 Negative electrode, 14 Electrolyte, 15 Separator, 16 Oxygen, 17 Surface, 18 Zinc oxide, 19 Calibration curve, 20 Zinc secondary battery charge control system, 21 Zinc secondary battery charge control device, 22 Interface unit, 23 Controller, 24 Storage device, 25, 26 Wire, 31 Receiving unit, 32 Charge rate measurement unit, 33 First determination unit, 34 Open circuit voltage measurement unit, 35 Difference calculation unit, 36 Second determination unit, 37 Oxygen generation suppression control implementation unit, 38 Charging restart unit.

Claims

1. A charging control method for a zinc secondary battery that controls charging of the zinc secondary battery, comprising: a receiving step of receiving an instruction to start charging the zinc secondary battery; a charging rate measurement step of measuring the charging rate of the zinc secondary battery after starting charging if the instruction to start charging is received in the receiving step; a first determination step of determining whether the charging rate measured in the charging rate measurement step has increased by a predetermined percentage compared to the charging rate before starting measurement; an open-circuit voltage measurement step of interrupting charging and measuring an open-circuit voltage value of the zinc secondary battery if it is determined in the first determination step that the charging rate measured has increased by the predetermined percentage; a difference calculation step of calculating the difference between the open-circuit voltage value measured in the open-circuit voltage measurement step and a predetermined ideal open-circuit voltage value; a second determination step of determining whether the difference calculated in the difference calculation step is equal to or greater than a predetermined value; and an oxygen generation suppression control implementation step of implementing oxygen generation suppression control to suppress oxygen generation during charging if it is determined in the second determination step that the difference is equal to or greater than the predetermined value. a charge restart step of restarting charging after carrying out the oxygen generation suppression control implementation step.

2. A charging control method for a zinc secondary battery as described in claim 1, in which the charging rate measurement process, the first judgment process, the open circuit voltage value measurement process, the difference calculation process, the second judgment process, the oxygen generation suppression control implementation process, and the charging resumption process are repeated at predetermined intervals.

3. A charging control method for a zinc secondary battery as described in claim 1 or claim 2, wherein the ideal open-circuit voltage value includes calibration curve data for the ideal open-circuit voltage value stored in a predetermined location.

4. A charging control method for a zinc secondary battery as described in claim 1 or claim 2, wherein charging of the zinc secondary battery is performed by constant voltage charging, and the oxygen generation suppression control implementation process includes a process of lowering the voltage value during the constant voltage charging.

5. A charging control method for a zinc secondary battery as described in claim 1 or claim 2, wherein charging of the zinc secondary battery is performed by constant current charging, and the oxygen generation suppression control implementation process includes a process of lowering the current value in the constant current charging.

6. A charging control method for a zinc secondary battery as described in claim 1 or claim 2, wherein if the second judgment step determines that the difference is less than the predetermined value, charging is continued without performing the oxygen generation suppression control.

7. A charging control method for a zinc secondary battery according to claim 1 or claim 2, wherein the predetermined value is 5 mV or more and 50 mV or less.

8. A charging control method for a zinc secondary battery according to claim 1 or claim 2, wherein the predetermined percentage is between 1% and 20%.

9. The charging control method for a zinc secondary battery according to claim 2, wherein the predetermined timing is between 1 second and 300 seconds.

10. A charge control device for a zinc secondary battery that controls charging of the zinc secondary battery, comprising: a reception unit that receives an instruction to start charging the zinc secondary battery; a charging rate measurement unit that measures the charging rate of the zinc secondary battery after starting charging when the instruction to start charging is received by the reception unit; a first determination unit that determines whether the charging rate measured by the charging rate measurement unit has increased by a predetermined percentage compared to the charging rate before measurement started; an open-circuit voltage measurement unit that interrupts charging and measures an open-circuit voltage value of the zinc secondary battery when the first determination unit determines that the charging rate measured has increased by the predetermined percentage; a difference calculation unit that calculates the difference between the open-circuit voltage value measured by the open-circuit voltage measurement unit and a predetermined ideal open-circuit voltage value; a second determination unit that determines whether the difference calculated by the difference calculation unit is equal to or greater than a predetermined value; and an oxygen generation suppression control implementation unit that implements oxygen generation suppression control to suppress oxygen generation during charging when the second determination unit determines that the difference is equal to or greater than the predetermined value. a charge restart unit that restarts charging after the oxygen generation suppression control execution unit has executed the charge control control for a zinc secondary battery.

11. A charging control system for a zinc secondary battery that controls charging of a zinc secondary battery, comprising: a zinc secondary battery; a memory unit that stores data on a predetermined ideal open-circuit voltage value when charging the zinc secondary battery; a receiving unit that receives an instruction to start charging the zinc secondary battery; a charging rate measurement unit that measures the charging rate of the zinc secondary battery after starting charging if the receiving unit receives an instruction to start charging; a first determination unit that determines whether the charging rate measured by the charging rate measurement unit has increased by a predetermined percentage compared to the charging rate before measurement started; an open-circuit voltage measurement unit that interrupts charging and measures the open-circuit voltage value of the zinc secondary battery if the first determination unit determines that the charging rate measured has increased by the predetermined percentage; a difference calculation unit that calculates the difference between the open-circuit voltage value measured by the open-circuit voltage measurement unit and the ideal open-circuit voltage value stored in the memory unit; and a second determination unit that determines whether the difference calculated by the difference calculation unit is equal to or greater than a predetermined value. A charging control system for a zinc secondary battery, comprising: an oxygen generation suppression control implementation unit that implements oxygen generation suppression control to suppress oxygen generation during charging if the second judgment unit determines that the difference is equal to or greater than the predetermined value; and a charging restart unit that restarts charging after implementing the oxygen generation suppression control implementation unit.

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