JP2010061970A - Charge system, and charging method for secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems wherein there is a possibility that performance and reliability of a secondary battery may be reduced when the secondary battery is used or stored under a high temperature environment. <P>SOLUTION: A discharge circuit 24 performs electric discharge in a charge system 1 when a temperature of the secondary battery 11 is higher than the upper limit of a temperature range where charging of the secondary battery 11 is allowed. A first safety element 25 stops an operation of a charge circuit 23 and the discharge circuit 24 when the temperature of the secondary battery 11 is higher than a first temperature and lower than a second temperature, and resumes the operation of the charge circuit 23 or the discharge circuit 24 when the temperature of the secondary battery 11 is reduced to or below the first temperature. Furthermore, a second safety element 26 stops the operation of the charge circuit 23 and the discharge circuit 24 when the temperature of the secondary battery 11 is the second temperature or more, and still stops the operation of the charge circuit 23 and the discharge circuit 24 when the temperature of the secondary battery 11 is less than the second temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a charging system and a charging method for a secondary battery, and more particularly, to a charging system and a secondary battery used when charging a non-aqueous electrolyte secondary battery suitably applied to a battery power source of a small portable electronic device or the like. The present invention relates to a secondary battery charging method, and further relates to a charging system and a secondary battery charging method capable of charging a non-aqueous electrolyte secondary battery in accordance with an ambient environmental temperature.

  In recent years, the progress of downsizing, thinning, lightening and high functionality of portable electronic devices has been remarkable, and accordingly, the battery serving as the power source has been required to be downsized, thinning, lightening and high capacity. Yes. A non-aqueous electrolyte secondary battery is most suitable as a small, thin, light and high capacity battery, and among them, a lithium secondary battery is most suitable. Today, as a battery that can be used repeatedly, the application of a lithium secondary battery to a portable electronic device such as a mobile phone or a notebook computer is increasing.

  Such a nonaqueous electrolyte secondary battery, particularly a lithium secondary battery, is generally said to deteriorate in performance under a high temperature atmosphere. The cause is that the non-aqueous electrolyte is decomposed by reacting with the positive electrode active material in a high temperature atmosphere, and as a result, gas is generated, or a part of the transition metal in the positive electrode active material is not in the high temperature atmosphere. It is considered to dissolve in a water electrolyte.

  In order to prevent the performance deterioration of the nonaqueous electrolyte secondary battery in a high temperature atmosphere, a method of changing the charge setting voltage according to the environmental temperature is used. Specifically, since the charging speed is slow at low temperatures, the charging speed is increased by increasing the charging setting voltage, and at high temperatures and high voltages, the electrolyte and cathode active material are degraded and deteriorated. Low to prevent battery performance degradation.

  However, depending on the use of the secondary battery, the ambient temperature of the secondary battery during or after charging may vary significantly. For example, the temperature of a secondary battery used indoors rises to 20 ° C. or higher due to heating during the daytime in winter, but may drop to 0 ° C. or lower during the night in winter.

  In order to prevent the performance of the secondary battery from degrading when the ambient temperature of the secondary battery fluctuates in this way, a protection device for a secondary battery with a built-in thermal operation means and discharge means has been proposed. (For example, refer to Patent Document 1). In this secondary battery protection device, when the secondary battery is left in a high temperature atmosphere, the secondary battery is discharged to reduce the voltage of the secondary battery, thereby suppressing a decrease in battery capacity. The voltage of the secondary battery is prevented from dropping excessively with the discharge.

  However, the secondary battery protection device disclosed in Patent Document 1 has a drawback in that the charge setting voltage cannot be increased when the secondary battery is moved from a high temperature atmosphere to a low temperature atmosphere. In order to overcome this drawback, there has been proposed a charging device including a charge control means for increasing the charge setting voltage of the secondary battery when the temperature is low, and lowering the charge setting voltage of the secondary battery when the temperature is high. (For example, refer to Patent Document 2).

  By the way, recently, as a portable electronic device has been driven for a long time and reduced in weight, the environment in which the nonaqueous electrolyte secondary battery is placed is diversified. For example, the number of cases in which nonaqueous electrolyte secondary batteries are used or stored in a high-temperature atmosphere, such as on-board, installation in a bath or sauna, long-term outdoor use, and use in high-temperature areas, is greatly increased. is doing.

  For example, when a non-aqueous electrolyte secondary battery is used as a portable navigation power source, in summer, a device charged in a room near 20 ° C. by cooling will be installed on the dashboard inside the vehicle whose temperature has risen to around 80 ° C. Can be used. Therefore, there is a possibility that the temperature of the nonaqueous electrolyte secondary battery rises to near 80 ° C.

In addition, when the nonaqueous electrolyte secondary battery is used outdoors or in an area where the temperature is high, the temperature of the nonaqueous electrolyte secondary battery increases as the usage time increases, and in some cases, the temperature may increase to close to 80 ° C. There is.
JP-A-4-137371 JP-A-6-197466

  However, Patent Documents 1 and 2 do not disclose a method for ensuring the safety of a secondary battery when the secondary battery is used or stored in a high temperature atmosphere. Therefore, in the charging devices disclosed in Patent Documents 1 and 2, when the secondary battery is used or stored in a high temperature atmosphere, the nonaqueous electrolyte and the positive electrode active material react to generate gas, or the positive electrode There is a possibility that the transition metal in the active material is dissolved in the non-aqueous electrolyte and the performance of the secondary battery is lowered.

  Therefore, in view of the above-described conventional problems, the present invention suppresses the performance degradation of the secondary battery even when the secondary battery is used or stored in a high-temperature atmosphere, and has a highly reliable charging system and secondary battery. The purpose is to provide a charging method.

  The charging system of the present invention includes a secondary battery, a charging circuit, a discharging circuit, a first safety element, and a second safety element. The charging circuit charges the secondary battery when the temperature of the secondary battery is equal to or lower than the upper limit temperature of the temperature range in which the secondary battery can be charged. The discharge circuit discharges the secondary battery when the temperature of the secondary battery is higher than the upper limit temperature and lower than the first temperature. The first safety element stops the operation of the charging circuit and the discharging circuit when the temperature of the secondary battery is higher than the first temperature and lower than the second temperature, while the temperature of the secondary battery is higher than the first temperature. When the temperature falls from the temperature lower than the second temperature to the first temperature or lower, the operation of the charging circuit or the discharging circuit is resumed. The second safety element stops the operation of the charging circuit and the discharging circuit when the temperature of the secondary battery is equal to or higher than the second temperature, while the charging circuit also stops when the temperature of the secondary battery falls below the second temperature. And the operation of the discharge circuit remains stopped.

  In the above configuration, the secondary battery can be safely charged.

  In the above configuration, since the secondary battery is used or stored in a high temperature atmosphere, the secondary battery is used if the temperature falls below the first temperature even if the temperature becomes higher than the first temperature. Can do. Therefore, it is economical and excellent in convenience.

  Further, in the above configuration, when the secondary battery becomes hot enough to cause the non-aqueous electrolyte and the positive electrode active material to react for some reason, use of the secondary battery is prohibited. Therefore, the safety of the secondary battery can be ensured.

  In the charging system of the present invention, it is preferable that the charging circuit does not charge the secondary battery when the temperature of the secondary battery is higher than the upper limit temperature, and the discharging circuit has a predetermined charging rate of the secondary battery. The secondary battery is preferably discharged until the predetermined charging rate is 30% or more and 50% or less. Thereby, the secondary battery can be charged while ensuring the safety of the secondary battery. Even when charging is stopped and the secondary battery is used, the secondary battery can be used for a relatively long time.

  In the charging system of the present invention, the charging circuit is configured such that when the secondary battery has a charging rate lower than a predetermined charging rate even when the temperature of the secondary battery is higher than the upper limit temperature and not higher than the first temperature, It is preferable to charge the secondary battery until the charging rate becomes a predetermined charging rate. As a result, the time required for charging can be shortened, and even when the secondary battery is used after charging is stopped, the secondary battery can be used for a relatively long time. At this time, the discharge circuit may discharge the secondary battery so that the charging rate of the secondary battery is lower than a predetermined charging rate. Thereby, since the voltage of a secondary battery can be reduced and the performance degradation by temperature can be improved rapidly, the safety | security of a secondary battery can be ensured.

  In the charging system of the present invention, the charging circuit preferably charges the secondary battery with a charge setting voltage of 4.00 V or more and 4.20 V or less and a charging current of 0.5 C or less, and the discharging circuit is 0.05 C or more. It is preferable to discharge the secondary battery by supplying a current of More preferably, the charge setting voltage is 4.05 V or more and 4.15 V or less. Thereby, deterioration of the secondary battery due to storage can be suppressed. In addition, it is possible to safely charge a secondary battery with a history stored at high temperatures, and use the secondary battery for a relatively long time even if charging is stopped and the secondary battery is used. Can do.

  In the charging system of the present invention, when the temperature of the secondary battery is 0 ° C. or higher and lower than the lower limit temperature of the temperature range in which the secondary battery can be charged, the temperature of the secondary battery is equal to or higher than the lower limit temperature. It is preferable to charge the secondary battery by lowering the charge setting voltage and the charging current than when the temperature is not more than the upper limit temperature. Specifically, a half current may be supplied. Thereby, deterioration of the secondary battery at low temperature can be prevented. The lower limit temperature is 10 ° C., for example.

  In the charging system of the present invention, the upper limit temperature is, for example, 40 ° C. or more and 50 ° C. or less, the first temperature is, for example, 80 ° C. or more and 90 ° C. or less, and the second temperature is, for example, 100 ° C. or more. When the secondary battery is used or stored in a high temperature atmosphere, it is considered that there is relatively little deterioration until the vicinity of the first temperature when the charging depth is low, and when the second temperature is exceeded, the nonaqueous electrolyte and It is said that the reaction with the positive electrode active material becomes remarkable.

  In the charging system of the present invention, at least one of the first safety element and the second safety element may be provided in the secondary battery.

  The charging system of the present invention preferably includes a temperature sensor that measures the temperature of the secondary battery and a voltage sensor that measures the voltage of the secondary battery.

  The method for charging the secondary battery of the present invention includes the step (a) of charging the secondary battery when the temperature of the secondary battery is equal to or lower than the upper limit temperature of the chargeable temperature range of the secondary battery, and the secondary battery Step (b) of discharging the secondary battery when the temperature of the battery is higher than the upper limit temperature and lower than the first temperature; and charging the secondary battery when the temperature of the secondary battery exceeds the first temperature And a step (c) of stopping the discharge. In step (c), when the temperature of the secondary battery is higher than the first temperature and lower than the second temperature, when the temperature of the secondary battery becomes equal to or lower than the first temperature after step (c), step (a ) Or step (b). In addition, when the temperature of the secondary battery is equal to or higher than the second temperature in step (c), charging and discharging of the secondary battery are performed even after the temperature of the secondary battery falls below the second temperature after step (c). Perform step (d) to remain stopped.

  In the above method, the secondary battery can be charged safely. In addition, a secondary battery charging method that is economical and convenient can be provided, and further, the safety of the secondary battery can be ensured.

  In the charging method of the present invention, step (b) is performed after step (a). In step (b), when the temperature of the secondary battery exceeds the upper limit temperature, charging of the secondary battery is stopped and It is preferable to discharge the secondary battery until the charging rate of the secondary battery reaches a predetermined charging rate, and perform step (a) again after step (b). The predetermined charging rate is preferably 30% or more and 50% or less. Thereby, it can suppress that the time which charge requires becomes redundant, and even if it is a case where charge is stopped and a secondary battery is used, a secondary battery can be used for a comparatively long time.

  In the charging method of the present invention, when the temperature of the secondary battery is higher than the upper limit temperature and not higher than the first temperature and the charging rate of the secondary battery is lower than the predetermined charging rate, the charging rate of the secondary battery is predetermined. It is preferable to include the step (e) of charging the secondary battery until the charging rate becomes. At this time, before step (e), step (f) of discharging the secondary battery until the charge rate of the secondary battery falls below a predetermined charge rate may be performed. As a result, the time required for charging can be shortened, and the voltage of the secondary battery can be reduced and the performance degradation due to temperature can be quickly improved, so the safety of the secondary battery can be ensured. .

  In the charging method of the present invention, when the temperature of the secondary battery is 0 ° C. or higher and lower than the lower limit temperature of the temperature range in which the secondary battery can be charged, the temperature of the secondary battery is higher than the lower limit temperature and the upper limit. It is preferable that the method further includes a step (g) of charging the secondary battery by lowering the charge setting voltage and the charging current than when the temperature is equal to or lower than the temperature. Thereby, deterioration of the secondary battery at low temperature can be prevented.

  According to the present invention, even when a secondary battery is used or stored in a high-temperature atmosphere, the performance of the secondary battery can be suppressed and the reliability can be improved.

  Before describing the embodiment according to the present invention, what the present inventors have studied in completing the present application will be described.

  Nowadays, it is required to use a lithium secondary battery (hereinafter referred to as “secondary battery”) as a power source for portable electronic devices. With this requirement, it is considered that the temperature atmosphere in which the secondary battery is placed is diversified. Therefore, it is preferable to expand the usable temperature range of the secondary battery.

  On the other hand, in the secondary battery, when the temperature of the secondary battery becomes high (100 ° C. or higher), the secondary battery may be deteriorated as described above. Therefore, it is preferable that the temperature of the secondary battery does not exceed 100 ° C., or that the secondary battery is not used when the temperature of the secondary battery exceeds 100 ° C.

  Therefore, the inventors of the present application studied charging a secondary battery using the charging device described in Patent Document 2. Patent Document 2 discloses parameters necessary for charging a secondary battery using this charging device (temperature of a secondary battery when switching from charge to discharge, charge setting voltage at low temperature and high temperature, In addition, the current value during discharge, etc.) is not disclosed. For this reason, the inventors of the present application optimized the numerical values of these parameters to charge the secondary battery. Then, in this charging device, the safety of the secondary battery can be secured when the temperature of the secondary battery rises to around 80 ° C., but the safety of the secondary battery is secured when the temperature of the secondary battery exceeds 80 ° C. It turns out that sex cannot be secured.

By the way, the conventional secondary battery is provided with a resettable protection element that operates at 80 to 100 ° C. or a non-recoverable protection element that operates at 80 to 100 ° C. The reset-type protection element stops charging and discharging of the secondary battery when the temperature of the secondary battery exceeds its operating temperature, but when the temperature of the secondary battery falls below its operating temperature after that, Charging or discharging (mainly discharging) is resumed. On the other hand, the non-recoverable protection element stops the charging and discharging of the secondary battery when the temperature of the secondary battery exceeds its operating temperature, and after that, even if the temperature of the secondary battery falls below its operating temperature. Do not resume charging and discharging of the secondary battery. The inventors of the present application studied to provide one of the protective elements provided in the conventional secondary battery in the charging device described in Patent Document 2.
(1) Charging device provided with a reversible protective element that operates at 80 to 100 ° C. In this charging device, the secondary battery cannot be used when the temperature of the secondary battery reaches 80 to 100 ° C., but the temperature drops. The secondary battery can be used again. In general, for secondary batteries installed in equipment that is not exposed to a high temperature environment, even if the temperature rises to about 80 to 90 ° C., it is considered that it will not deteriorate so much in a short time. So it is economical.

  Further, when the secondary battery is used or stored in a high temperature atmosphere, the temperature of the secondary battery may rise to about 80 ° C. Even in such a case, if the temperature of the secondary battery falls below 80 ° C., the secondary battery can be used again. Therefore, the convenience of the secondary battery is improved.

  However, in this charging device, even when the temperature of the secondary battery becomes 100 ° C. or higher, the secondary battery is discharged or charged again. When the temperature is 100 ° C. or higher, the performance of the secondary battery may be lowered, and it is dangerous to recharge or discharge the secondary battery whose performance may be lowered. Therefore, it is difficult to ensure the safety of the secondary battery.

As described above, with this charging device, it is possible to improve economy and convenience, but it is difficult to ensure the safety of the secondary battery.
(2) Charging device provided with non-recoverable protection element that operates at 80 to 100 ° C. In this charging device, the use of the secondary battery can be prohibited even if the temperature of the secondary battery has not reached 100 ° C. . Therefore, the safety of the secondary battery can be ensured as compared with the charging device of (1).

  However, even if the temperature rises to 80 to 90 ° C., the secondary battery does not deteriorate so much in a short time. Therefore, this charging device is uneconomical because the use of a secondary battery that has not deteriorated so much is prohibited.

  In addition, as described above, the use of a secondary battery exposed to a high temperature environment has increased in recent years. Therefore, when a secondary battery is used or stored in a high temperature atmosphere, the temperature of the secondary battery is 80. It rises to about ℃. Therefore, when this charging device is incorporated in a portable electronic device, the frequency at which the portable electronic device becomes unusable increases. As a result, the user must request the manufacturer to replace the secondary battery every time the portable electronic device becomes unusable, and until the portable electronic device that can be used is retransmitted by the manufacturer. Portable electronic devices cannot be used. Each time the manufacturer receives a report from the user that the portable electronic device has become unusable, the manufacturer replaces the secondary battery, resends the portable electronic device that has become usable to the user, If there is a shortage of secondary batteries, work must be done to order a secondary battery from the battery manufacturer. As described above, when this charging device is incorporated in a portable electronic device, convenience is deteriorated and work efficiency in the manufacturer is reduced.

  As described above, with this charging device, the safety of the secondary battery can be ensured, but it is uneconomical, and when incorporated in a portable electronic device, the convenience is deteriorated and the work efficiency at the manufacturer is reduced. .

  As described above, in any of the charging devices (1) and (2), all of the economic efficiency, the convenience, the work efficiency at the manufacturer, and the safety of the secondary battery are all provided. It has been found that a charging device that satisfies the requirements cannot be provided.

  The inventors of the present invention completed the present invention based on the results of this study. Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to embodiment shown below.

Embodiment 1 of the Invention
FIG. 1 is a block diagram of a charging system according to the present embodiment.

  As shown in FIG. 1, the charging system 1 according to the present embodiment includes a secondary battery 11, a voltage sensor 21, a temperature sensor 22, a charging circuit 23, a discharging circuit 24, a first safety element 25, And a second safety element 26. The secondary battery 11 is a battery that is charged in the charging system 1 and is not limited as long as it is a chargeable / dischargeable battery. In the present embodiment, a lithium secondary battery will be described as an example. The secondary battery 11 is a power source for the electronic device 20. The electronic device 20 includes a voltage sensor 21, a temperature sensor 22, a charging circuit 23, a discharging circuit 24, a first safety element 25, and a second safety element 26. It is.

  The voltage sensor 21 is, for example, an IC (integrated circuit), and measures the voltage of the secondary battery.

  The temperature sensor 22 is, for example, a thermistor, an IC temperature sensor, a thermocouple, and the like, and measures the temperature of the secondary battery 11.

  The charging circuit 23 operates based on the voltage measured by the voltage sensor 21 and the temperature measured by the temperature sensor 22, and when the temperature measured by the temperature sensor 22 is equal to or lower than the upper limit temperature of the chargeable temperature range, the charging circuit 23 is secondary. The battery 11 is charged, but the secondary battery 11 is not charged when the temperature measured by the temperature sensor 22 exceeds the upper limit temperature (for example, 40 ° C. or more and 50 ° C. or less) of the chargeable temperature range.

  In the charging circuit 23, the charge setting voltage is preferably 4.00 V or more and 4.20 V or less, more preferably the charge setting voltage is 4.05 V or more and 4.15 V or less, and the charging current is 0.5 C or less. It is preferable that Thereby, even if the secondary battery 11 is preserve | saved after charge, deterioration of the secondary battery 11 can be suppressed small. In order to prevent the time required for charging from becoming redundant, the charging current may be 0.2 C or more.

  The discharge circuit 24 operates based on the voltage measured by the voltage sensor 21 and the temperature measured by the temperature sensor 22, and is charged when the temperature measured by the temperature sensor 22 exceeds the upper limit temperature of the chargeable temperature range. The secondary battery 11 is discharged until the rate reaches a predetermined charging rate. Here, the predetermined charging rate is assumed to be 30% or more and 50% or less.

  In the discharge circuit 24, the discharge current value is preferably 0.05C or more, and more preferably 0.5C or less. If this current value is too small (below 0.05 C), the voltage of the secondary battery 11 cannot be lowered quickly, and performance deterioration due to temperature may not be improved. On the other hand, if the current value is too large (over 0.5 C), heat may be generated during discharge, which makes it difficult to obtain the effect of lowering the temperature of the secondary battery 11, which is not preferable. In addition, the charging rate of the secondary battery 11 is calculated | required using the voltage which the voltage sensor 21 measured. As described above, when the charge setting voltage is 4.00 V or more and 4.20 V or less, if the voltage measured by the voltage sensor 21 is 3.7 V, the charging rate is about 30%, and the voltage measured by the voltage sensor 21 is Is 3.85V, the charging rate is about 50%.

  The first safety element 25 is, for example, a PTC (Positive Temperature Coefficient) element or a thermostat, and is designed to operate upon detecting that the temperature of the secondary battery 11 has exceeded the first temperature. Specifically, when it is detected that the temperature of the secondary battery 11 is higher than the first temperature and lower than the second temperature, the first safety element 25 performs charging by the charging circuit 23 and discharging by the discharging circuit 24. On the other hand, when it is detected that the temperature of the secondary battery 11 has dropped from a temperature higher than the first temperature and lower than the second temperature to the first temperature or lower, charging by the charging circuit 23 or discharging by the discharging circuit 24 is performed. To resume.

  The second safety element 26 is a thermal fuse, for example, and is designed to operate by detecting that the temperature of the secondary battery 11 has reached the second temperature or higher. Specifically, when it is detected that the temperature of the secondary battery 11 is equal to or higher than the second temperature, the charging by the charging circuit 23 and the discharging by the discharging circuit 24 are stopped, while the temperature of the secondary battery 11 is the second temperature. Even when it is detected that the value has become less than, charging by the charging circuit 23 and discharging by the discharging circuit 24 are not resumed.

  In the first safety element 25 and the second safety element 26, the temperature of the secondary battery 11 when the secondary battery 11 is used or stored in a high temperature atmosphere is assumed as the first temperature. Assumes 80-90 ° C. Moreover, 100 degreeC is assumed as 2nd temperature, and when it becomes 100 degreeC or more, there exists a possibility that a nonaqueous electrolyte and a positive electrode may react and a secondary battery may deteriorate.

  Below, the operation | movement in the charging system 1 which concerns on this embodiment for a case according to the temperature of the secondary battery 11 is shown.

  First, the case where the temperature of the secondary battery 11 is within the chargeable temperature range will be described with reference to FIG. FIG. 2 shows changes in the temperature of the secondary battery 11 and the voltage of the secondary battery 11 when the secondary battery 11 is charged when the temperature of the secondary battery 11 before charging is around room temperature (Tr). FIG.

  In general, the temperature of the secondary battery 11 is easily affected by the environmental temperature around the secondary battery 11. Therefore, when the environmental temperature around the secondary battery 11 rises (for example, when the electronic device 20 including the secondary battery 11 is exposed to a high temperature environment), the temperature of the secondary battery 11 becomes the initial temperature Tr. And then rises to the upper limit temperature Tc (high) of the chargeable temperature range. At this time, if the secondary battery 11 is being charged, the safety of the secondary battery 11 may not be ensured if charging is continued thereafter. Therefore, in the charging system 1, the charging circuit 23 stops charging and the discharging circuit 24 starts discharging at time t1 when the temperature of the secondary battery 11 rises to Tc (high).

  When the discharge is started, the voltage of the secondary battery 11 starts to decrease from the charging setting voltage Vi, and the charging rate of the secondary battery 11 eventually decreases to a predetermined charging rate. Even if the discharge continues further, it is difficult to improve the safety of the secondary battery 11. Further, if the discharge is continued any longer, the time required for charging becomes longer, and further, when charging is stopped and the secondary battery 11 is used, the capacity of the secondary battery 11 is quickly lost. There is a fear. Therefore, the discharge circuit 24 stops discharging at a time point t2 when the charging rate decreases to a predetermined charging rate (when the voltage of the secondary battery 11 becomes Vf).

  Thereafter, when the environmental temperature around the secondary battery 11 starts to decrease, the temperature of the secondary battery 11 starts to decrease from the maximum temperature Tmax. Then, at the time t3 when the temperature of the secondary battery 11 falls to the upper limit temperature Tc (high) of the chargeable temperature range, the charging circuit 23 resumes charging. The secondary battery 11 can be charged by repeating the above operation.

  The upper limit temperature Tc (high) of the chargeable temperature range is 40 ° C. or more and 50 ° C. or less, and the charge setting voltage Vi is 4.00 V or more and 4.20 V or less, preferably 4.05 V or more and 4.15 V or less. The voltage Vf is 3.7V (charging rate is about 30%) or more and 3.85V (charging rate is about 50%) or less.

  Next, the case where the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range and not higher than the first temperature will be described.

Since the temperature measured by the temperature sensor 22 is higher than the upper limit temperature of the chargeable temperature range and not higher than the first temperature, the discharge circuit 24 starts discharging. Then, after the discharging circuit 24 discharges the secondary battery 11 until the charging rate reaches a predetermined charging rate, when the temperature measured by the temperature sensor 22 falls below the upper limit temperature of the chargeable temperature range, the charging circuit 23 Starts charging the secondary battery 11. Thereby, the secondary battery 11 can be charged safely.

Subsequently, the case where the temperature of the secondary battery 11 is higher than the first temperature and lower than the second temperature will be described.

  When detecting that the temperature of the secondary battery 11 is higher than the first temperature and lower than the second temperature, the first safety element 25 stops the operation of the charging circuit 23 and the discharging circuit 24. Therefore, charging and discharging of the secondary battery 11 are stopped. After a while, the temperature of the secondary battery 11 decreases. And if the 1st safety element 25 detects that the temperature of the secondary battery 11 fell to 1st temperature or less, it will restart the action | operation of the charging circuit 23 or the discharge circuit 24. FIG. Therefore, charging or discharging of the secondary battery 11 is resumed.

  Thus, when the temperature of the secondary battery 11 exceeds the first temperature, the use of the secondary battery 11 is prohibited until the temperature of the secondary battery 11 becomes equal to or lower than the first temperature. Therefore, since the voltage of the secondary battery 11 can be prevented from increasing, the safety of the secondary battery 11 can be ensured.

  Further, even when the temperature of the secondary battery 11 exceeds the first temperature because the secondary battery 11 is used or stored in a high temperature atmosphere, if the temperature of the secondary battery 11 falls to the first temperature or lower, A secondary battery 11 can be used. Therefore, it is economical, and the convenience of the secondary battery 11 can be improved while ensuring the safety of the secondary battery 11. Moreover, since the frequency | count of replacement | exchange work etc. of the secondary battery 11 in the manufacturer of the electronic device 20 can be reduced, the fall of the work efficiency in the manufacturer of the electronic device 20 can be suppressed.

  In particular, if the secondary battery 11 is used as a power source for a portable electronic device, it is considered that the number of cases where the portable electronic device is used or stored in a high temperature atmosphere increases. The charging system 1 according to the present embodiment is particularly useful in such a case.

  Subsequently, a case where the temperature of the secondary battery 11 is equal to or higher than the second temperature will be described.

  When detecting that the temperature of the secondary battery 11 is equal to or higher than the second temperature, the second safety element 26 stops the operation of the charging circuit 23 and the discharging circuit 24. Therefore, charging and discharging of the secondary battery 11 are stopped. After a while, the temperature of the secondary battery 11 decreases. However, even if the second safety element 26 detects that the temperature of the secondary battery 11 has dropped to below the second temperature, the operation of the charging circuit 23 and the discharging circuit 24 remains stopped. Thus, since the use of the secondary battery 11 whose performance may be deteriorated can be prohibited, the safety of the secondary battery 11 can be ensured.

  As described above, in the charging system 1 according to this embodiment, the secondary battery 11 can be safely charged.

  Further, the charging system 1 according to the present embodiment is provided with both the first safety element 25 and the second safety element 26. Therefore, the safety of the secondary battery 11 can be ensured as compared with the charging device (1). Further, it is more economical and convenient than the charging device of (2) above, and further, it is possible to suppress a decrease in work efficiency for the manufacturer of the electronic device 20.

  In addition, the 1st safety element 25 and the 2nd safety element 26 may be provided in the position shown below. For example, in the charging system 101 shown in FIG. 3A, the first safety element 25 is incorporated in the secondary battery 111, and the second safety element 26 is the electronic device 120 as in the charging system 1 according to the present embodiment. Built in. In the charging system 201 shown in FIG. 3B, both the first safety element 25 and the second safety element 26 are incorporated in the secondary battery 211, not in the electronic device 220. Further, although not shown, the first safety element may be incorporated in the electronic device, and the second safety element may be incorporated in the secondary battery. In any case, the same effect as the charging system 1 according to the present embodiment can be obtained.

  FIG. 4 is a flowchart showing the operation of the charging system 1 according to this embodiment.

  First, it progresses to step S101 and it is judged whether the temperature (it describes as "battery temperature" in FIG. 4) of the secondary battery 11 is more than 2nd temperature. If it is determined that the temperature of the secondary battery 11 is equal to or higher than the second temperature (Yes), the process proceeds to step S102 to stop the charging and discharging of the secondary battery 11 so that the secondary battery 11 cannot be used. (Step (d)). On the other hand, when it is determined that the temperature of the secondary battery 11 is lower than the second temperature (No), the process proceeds to step S103.

  In step S103, it is determined whether or not the temperature of the secondary battery 11 is higher than the first temperature. And when it is judged that the temperature of the secondary battery 11 is higher than 1st temperature (Yes), it progresses to step S104 and stops charge and discharge to the secondary battery 11 (step (c)). Then, it returns to step S103 and it is judged whether the temperature of the secondary battery 11 is higher than 1st temperature, and if the temperature of the secondary battery 11 is higher than 1st temperature, the present condition will be maintained. And this loop is repeated until the temperature of the secondary battery 11 becomes below 1st temperature. On the other hand, if it is determined in step S103 that the temperature of the secondary battery 11 is equal to or lower than the first temperature (No), the process proceeds to step S105.

  In step S105, it is determined whether or not the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range. And when it is judged that the temperature of the secondary battery 11 is higher than the upper limit temperature of the temperature range which can be charged (Yes), it progresses to below-mentioned step S108. On the other hand, when it is determined that the temperature of the secondary battery 11 is equal to or lower than the upper limit temperature of the chargeable temperature range (No), the process proceeds to step S106 and charging is started (step (a)). Thereafter, the process proceeds to step S107.

  In step S107, as in step S105, it is determined whether or not the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range. And when it is judged that the temperature of the secondary battery 11 is below the upper limit temperature of the temperature range which can be charged (No), since the secondary battery 11 can be charged, it returns to step S106 and the secondary battery 11 To charge.

  On the other hand, when it is determined in step S107 that the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range (Yes), the process proceeds to step S108 to stop charging and start discharging (step ( b)). Further, when it is determined in step S105 that the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range (Yes), the process proceeds to step S108 to start discharging (step (b)). Thereafter, the process proceeds to step S109.

  In step S109, it is determined whether the charging rate is equal to or lower than a predetermined charging rate. When it is determined that the charging rate exceeds the predetermined charging rate (No), the process returns to step S108. On the other hand, when it is determined that the charging rate is equal to or lower than the predetermined charging rate (Yes), the process proceeds to step S110 to stop discharging (step (c)), and then returns to step S101.

  After returning to step S101, the process proceeds to step S105 through step S103. If the temperature of the secondary battery 11 is higher than the upper limit temperature of the chargeable temperature range in step S105 (Yes), the process proceeds to step S108 and then step S109. However, since the charging rate is equal to or lower than the predetermined charging rate (Yes), the discharge stop is maintained. On the other hand, after returning to step S101, the process proceeds to step S105 through step S103. If the temperature of the secondary battery 11 is equal to or lower than the upper limit temperature of the chargeable temperature range in step S105 (No), the process proceeds to step S106 and charging is performed. Is started (step (a)).

  As described above, in the secondary battery charging method according to the present embodiment, the temperature of the secondary battery 11 is measured before charging or discharging, so the temperature of the secondary battery 11 can be charged. When the temperature is higher than the upper limit temperature of the range, the secondary battery 11 can be prevented from being erroneously charged. Therefore, the secondary battery 11 can be charged safely.

  Further, even if the temperature of the secondary battery 11 exceeds the first temperature because the secondary battery 11 is used or stored in a high temperature atmosphere, the secondary battery 11 is reduced to the first temperature. The battery can be used again. Therefore, it is economical, excellent in convenience, and for the manufacturer of the electronic device provided with the secondary battery 11, it is possible to suppress a decrease in work efficiency.

  Furthermore, it is possible to prohibit the use of a secondary battery in which the performance of the secondary battery may be degraded.

<< Embodiment 2 of the Invention >>
In the said Embodiment 1, if the temperature of a secondary battery is higher than the upper limit temperature of the temperature range which can be charged, it will not charge. However, it is known that even if the temperature of the secondary battery is high, if the voltage of the secondary battery is low, the safety of the secondary battery does not deteriorate so much. Therefore, in Embodiment 2 of the present invention, charging is performed when the voltage of the secondary battery is low. First, a charging system according to the present embodiment is shown.

  As in the first embodiment, the charging system according to the present embodiment includes a secondary battery, a temperature sensor, a voltage sensor, a charging circuit, a discharging circuit, a first protection element, and a second protection element. The function of the charging circuit is different between the present embodiment and the first embodiment.

  As in the first embodiment, the charging circuit in the present embodiment charges the secondary battery when the temperature measured by the temperature sensor is equal to or lower than the upper limit temperature of the chargeable temperature range, and the temperature measured by the temperature sensor is When the upper limit temperature of the rechargeable temperature range is exceeded, the secondary battery is not charged. In addition, the charging circuit is charged when the temperature measured by the temperature sensor is higher than the upper limit temperature of the chargeable temperature range and lower than the first temperature, but the charging rate is below the predetermined charging rate. The secondary battery is charged until the rate reaches a predetermined charging rate. Thereby, compared with the charging system 1 which concerns on the said Embodiment 1, the shortening of the time required for charge of a secondary battery can be aimed at.

  In the charging circuit according to the present embodiment, the charging setting voltage and the charging current may be the same as those in the first embodiment or may be smaller than those in the first embodiment.

  FIG. 5 is a flowchart showing the operation of the charging system according to this embodiment.

  First, as in the first embodiment, the process proceeds to steps S101, S103, and S105 in order. If it is determined in step S105 that the temperature of the secondary battery (described as “battery temperature” in FIG. 5) is equal to or lower than the upper limit temperature of the chargeable temperature range (No), the process proceeds to step S106. Performs the same control as in the first embodiment. On the other hand, if it is determined in step S105 that the temperature of the secondary battery exceeds the upper limit temperature of the chargeable temperature range (Yes), the process proceeds to step S201.

  In step S201, it is determined whether the charging rate is below a predetermined charging rate. If it is determined that the charging rate is lower than the predetermined charging rate (Yes), the process proceeds to step S202 and the secondary battery is charged until the charging rate reaches the predetermined charging rate (step (f)). . Thereafter, the process returns to step S105, and the same control as in the first embodiment is performed. On the other hand, when it is determined that the charging rate is equal to or higher than the predetermined charging rate (No), since the safety of the secondary battery cannot be guaranteed if charging is performed, the process proceeds to step S108 and discharge is started. The same control as in the first mode is performed.

  Thus, in this embodiment, even if the temperature of the secondary battery is higher than the upper limit temperature of the chargeable temperature range and not higher than the first temperature, if the charge rate is below a predetermined charge rate, the charge rate is The secondary battery is charged until a predetermined charging rate is reached. Thereby, in this embodiment, not only the effect obtained in Embodiment 1 but also the effect that the time required for charging the secondary battery can be shortened.

<< Embodiment 3 of the Invention >>
In the first embodiment, the secondary battery is discharged until the charging rate reaches a predetermined charging rate. On the other hand, in Embodiment 3 of the present invention, the secondary battery is discharged until the charging rate falls below a predetermined charging rate. First, a charging system according to the present embodiment is shown.

  As in the first embodiment, the charging system according to the present embodiment includes a secondary battery, a temperature sensor, a voltage sensor, a charging circuit, a discharging circuit, a first protection element, and a second protection element. The functions of the charging circuit and the discharging circuit are different between the present embodiment and the first embodiment.

  As in the first embodiment, the charging circuit in the present embodiment charges the secondary battery when the temperature measured by the temperature sensor is equal to or lower than the upper limit temperature of the chargeable temperature range, and the temperature measured by the temperature sensor is When the upper limit temperature of the rechargeable temperature range is exceeded, the secondary battery is not charged. In addition, the charging circuit according to the present embodiment has a predetermined charging rate even when the temperature measured by the temperature sensor is higher than the upper limit temperature of the chargeable temperature range and equal to or lower than the first temperature, as in the second embodiment. When the charging rate is lower, the secondary battery is charged until the charging rate reaches a predetermined charging rate.

  The discharge circuit in the present embodiment discharges the secondary battery when the temperature measured by the temperature sensor exceeds the upper limit temperature of the chargeable temperature range as in the first embodiment, but is shown by the broken line in FIG. Thus, the secondary battery is discharged until the charging rate falls below a predetermined charging rate. Accordingly, the discharge current in the present embodiment is preferably large enough that heat generation due to discharge does not occur. For example, a current of about 0.2 C may be passed. In addition, if the first safety element is incorporated in the electronic device, the amount of heat generated due to the discharge can be kept low. Therefore, as the charging system according to the present embodiment, the charging system 1 shown in FIG. 1 or FIG. It is preferable to employ the charging system 101 shown in a). Thereby, the temperature of the secondary battery can be quickly lowered.

  FIG. 6 is a flowchart showing the operation of the charging system according to this embodiment.

  First, similarly to the first embodiment, the process proceeds to steps S101, S103, and S105. When it is determined in step S105 that the temperature of the secondary battery (described as “battery temperature” in FIG. 6) is equal to or lower than the upper limit temperature of the chargeable temperature range (No), the same as in the first embodiment. It progresses to step S106 and step S107. On the other hand, when it is determined in step S105 that the temperature of the secondary battery is higher than the upper limit temperature of the chargeable temperature range (Yes), the process proceeds to step S301 described later.

  If it is determined in step S107 that the temperature of the secondary battery is equal to or lower than the upper limit temperature of the rechargeable temperature range (No), the process returns to step S106, and thereafter, the same control as in the first embodiment is performed. On the other hand, if it is determined in step S107 that the temperature of the secondary battery is higher than the upper limit temperature of the chargeable temperature range (Yes), the process proceeds to step S301 to stop charging and the charging rate is a predetermined charging rate. It discharges until it falls below (step (f)). Further, when it is determined in step S105 that the temperature of the secondary battery is higher than the upper limit temperature of the temperature range in which charging is possible (Yes), the process proceeds to step S301 and is discharged until the charging rate falls below a predetermined charging rate ( Step (f)). Thereafter, the process proceeds to step S302.

  In step S302, the secondary battery is charged until the charging rate reaches a predetermined charging rate (step (e)). Thereafter, the process returns to step S101.

  In the charging method according to the present embodiment, after discharging at a charging rate lower than a predetermined charging rate in step S108 in the first embodiment (step (f)), charging is performed until the charging rate reaches a predetermined charging rate. (Step (e)).

  Thus, in this embodiment, it discharges until a charging rate falls below a predetermined charging rate. Thereby, in this embodiment, not only the effect acquired in the said Embodiment 1, but the effect that the voltage of a secondary battery can be dropped rapidly and the performance fall by temperature can be improved can also be acquired.

<< Embodiment 4 of the Invention >>
Embodiments 1 to 3 describe a method of charging a secondary battery when the temperature of the secondary battery becomes higher than the upper limit temperature of the temperature range in which the secondary battery can be charged. However, depending on how the secondary battery is used, for example, when the secondary battery is used in an area where the temperature is low, the temperature of the secondary battery is lower than the lower limit temperature of the chargeable temperature range. There is.

  Generally, it is known that a secondary battery deteriorates at a low temperature. The reason for this is that when the temperature of the secondary battery is lowered (around 0 ° C.), the conductivity in the nonaqueous electrolyte deteriorates, so lithium is deposited as a metal on the negative electrode, and as a result, lithium ions move from the negative electrode to the positive electrode. This is thought to be because the amount of Therefore, in Embodiment 4 of the present invention, a charging system and a charging method of the secondary battery in the case where the temperature of the secondary battery is lower than the lower limit temperature of the chargeable temperature range will be described.

  As in the first embodiment, the charging system according to the present embodiment includes a secondary battery, a temperature sensor, a voltage sensor, a charging circuit, a discharging circuit, a first protection element, and a second protection element. The function of the charging circuit is different between the present embodiment and the first embodiment.

  As in the first embodiment, the charging circuit in the present embodiment charges the secondary battery when the temperature measured by the temperature sensor is equal to or lower than the upper limit temperature of the chargeable temperature range, and the temperature measured by the temperature sensor is When the upper limit temperature of the rechargeable temperature range is exceeded, the secondary battery is not charged. In addition, the charging circuit reduces the charging setting voltage and the charging current when the temperature measured by the temperature sensor is lower than the lower limit temperature of the chargeable temperature range. Specifically, the charge setting voltage is preferably lowered to about 4.0 V if the voltage of the secondary battery is 4.1 V when the temperature is within the chargeable temperature range. Further, the charging current may be about ½ of the temperature range of the secondary battery within the chargeable temperature range. Thereby, precipitation of metallic lithium at the negative electrode can be suppressed, and deterioration at low temperatures can be prevented.

  Note that it is not preferable to reduce the charge setting voltage and charging current too much because the time required for charging becomes too long, and it is not possible to prevent the deposition of metallic lithium at the negative electrode unless the charge setting voltage and charging current are almost reduced. The secondary battery will be deteriorated. For this reason, it is preferable to set the charge setting voltage and the charge current so that deterioration of the secondary battery can be suppressed while preventing the time required for charging from becoming long.

  FIG. 7 is a flowchart showing the operation of the charging system according to this embodiment.

  First, similarly to the first embodiment, the process proceeds to steps S101, S103, and S105. If it is determined in step S105 that the temperature of the secondary battery (described as “battery temperature” in FIG. 7) is equal to or lower than the upper limit temperature of the chargeable temperature range (No), the process proceeds to step S401.

  In step S401, it is determined whether or not the temperature of the secondary battery is lower than the lower limit temperature of the chargeable temperature range. When it is determined that the temperature of the secondary battery is equal to or higher than the lower limit temperature of the chargeable temperature range (No), the process proceeds to step S106, and thereafter, the same control as that of the first embodiment is performed. On the other hand, if it is determined in step S401 that the temperature of the secondary battery is lower than the lower limit temperature of the chargeable temperature range (Yes), the process proceeds to step S402.

  In step S402, it is determined whether or not the temperature of the secondary battery is less than 0 ° C. And if the temperature of a secondary battery is less than 0 degreeC (Yes), it will progress to step S403 and will stop charge and discharge of a secondary battery. Then, it returns to step S401 and repeats the loop of step S401-S403 until the temperature of a secondary battery becomes 0 degreeC or more. On the other hand, if the temperature of the secondary battery is 0 ° C. or higher (No), the process proceeds to step S404 to lower the charge setting voltage and the current value during charging (step (g)). Thereafter, the process proceeds to step S106, and thereafter, the same control as in the first embodiment is performed.

  As described above, in this embodiment, when the temperature of the secondary battery is lower than the lower limit temperature of the temperature range in which the secondary battery can be charged at 0 ° C. or more, charging is performed by reducing the charge setting voltage and the charging current. Thereby, in this embodiment, not only the effect obtained in the first embodiment but also the effect that the secondary battery can be charged without depositing metallic lithium on the negative electrode can be obtained.

<< Other Embodiments >>
The above-described first to fourth embodiments may be configured as follows.

  The charging system may not have a temperature sensor and a voltage sensor. In that case, the charging circuit may measure the temperature and voltage of the secondary battery, the discharging circuit may measure the temperature and voltage of the secondary battery, and either the charging circuit or the discharging circuit. May measure the temperature of the secondary battery and the other may measure the voltage of the secondary battery, and the charging circuit and the discharging circuit may measure the temperature and voltage of the secondary battery.

  In the charging system, the first safety element and the second safety element may be designed to operate based on the temperature measured by the temperature sensor 21.

  A known secondary battery can be used as the secondary battery. Further, when a lithium ion secondary battery is used as the secondary battery, the electrode group may be an electrode group in which the electrode plate is wound or an electrode group in which the electrode plate is laminated, Known materials can be used as the active material and the current collector.

  The present invention is useful for a system or a charging method for charging a secondary battery useful for a main power source of an electronic device or the like. For example, the present invention provides a secondary battery useful for a main power source of a consumer mobile tool such as a mobile phone or a notebook computer, a main power source of a power tool such as an electric screwdriver, and an industrial main power source such as an EV (Electric vehicle). Suitable for charging system or charging method.

  Especially useful for the main power source of portable navigation systems, portable DVD (digital versatile disc) players, portable displays or portable TVs that have a display and may be exposed to high temperature environments such as cars or bathrooms. It is suitable for a system or a charging method for charging a secondary battery.

It is a block diagram of the charging system which concerns on Embodiment 1 of this invention. It is a graph which shows the change of the temperature of a secondary battery, and the voltage of a secondary battery when the secondary battery is charged when the temperature of the secondary battery before charge is near room temperature. (A) And (b) is a block diagram of another charge system in Embodiment 1 of the present invention, respectively. It is a flowchart which shows the operation | movement in the charging system which concerns on Embodiment 1 of this invention. It is a flowchart which shows the operation | movement in the charging system which concerns on Embodiment 2 of this invention. It is a flowchart which shows the operation | movement in the charging system which concerns on Embodiment 3 of this invention. It is a flowchart which shows the operation | movement in the charging system which concerns on Embodiment 4 of this invention.

Explanation of symbols

1,101,201 Charging system
11, 111, 211 Secondary battery
21 Voltage sensor
22 Temperature sensor
23 Charging circuit
24 Discharge circuit
25 First safety element
26 Second safety element

Claims (17)

A charging system for charging a secondary battery,
The secondary battery;
A charging circuit that charges the secondary battery when the temperature of the secondary battery is equal to or lower than an upper limit temperature of a chargeable temperature range of the secondary battery;
A discharge circuit for discharging the secondary battery when the temperature of the secondary battery is higher than the upper limit temperature and not higher than the first temperature;
When the temperature of the secondary battery is higher than the first temperature and lower than the second temperature, the operation of the charging circuit and the discharging circuit is stopped, while the temperature of the secondary battery is higher than the first temperature. And a first safety element that resumes the operation of the charging circuit or the discharging circuit when the temperature falls below the first temperature from the temperature lower than the second temperature;
When the temperature of the secondary battery is equal to or higher than the second temperature, the operation of the charging circuit and the discharging circuit is stopped, while the charging is also performed when the temperature of the secondary battery is lower than the second temperature. A charging system comprising: a circuit; and a second safety element that keeps the operation of the discharging circuit stopped. The charging system according to claim 1,
When the temperature of the secondary battery is higher than the upper limit temperature, the charging circuit does not charge the secondary battery,
The discharging circuit discharges the secondary battery until the charging rate of the secondary battery reaches a predetermined charging rate,
The charging system is characterized in that the predetermined charging rate is not less than 30% and not more than 50%. The charging system according to claim 1,
When the temperature of the secondary battery is higher than the upper limit temperature and lower than the first temperature and the charging rate of the secondary battery is lower than the predetermined charging rate, the charging circuit The charging system, wherein the secondary battery is charged until a charging rate reaches the predetermined charging rate. The charging system according to claim 3,
The discharging system discharges the secondary battery so that a charging rate of the secondary battery is lower than the predetermined charging rate. The charging system according to any one of claims 1 to 4,
The charging circuit charges the secondary battery with a charge setting voltage of 4.00 V to 4.20 V and a charging current of 0.5 C or less,
The charging system, wherein the discharge circuit discharges the secondary battery by passing a current of 0.05 C or more. The charging system according to claim 5, wherein
The charging system is characterized in that the secondary battery is charged by setting the charge setting voltage to 4.05 V or more and 4.15 V or less. The charging system according to any one of claims 1 to 6,
In the charging circuit, when the temperature of the secondary battery is 0 ° C. or higher and lower than the lower limit temperature of the temperature range in which the secondary battery can be charged, the temperature of the secondary battery is equal to or higher than the lower limit temperature and the upper limit A charging system characterized in that the secondary battery is charged by lowering a charge setting voltage and a charging current as compared to when the temperature is lower than the temperature. The charging system according to claim 7, wherein
When the temperature of the secondary battery is 0 ° C. or higher and lower than the lower limit temperature, the charging circuit determines the charging current when the temperature of the secondary battery is equal to or higher than the lower limit temperature and lower than the upper limit temperature. A charging system characterized by being ½ or less of the above. The charging system according to claim 7 or 8,
The said minimum temperature is 10 degreeC, The charging system characterized by the above-mentioned. The charging system according to any one of claims 1 to 9,
The upper limit temperature is 40 ° C. or more and 50 ° C. or less,
The first temperature is 80 ° C. or higher and 90 ° C. or lower,
The charging system, wherein the second temperature is 100 ° C or higher. The charging system according to any one of claims 1 to 10,
At least one of the first safety element and the second safety element is provided in the secondary battery. The charging system according to any one of claims 1 to 11,
A temperature sensor for measuring the temperature of the secondary battery;
A charging system comprising: a voltage sensor that measures a voltage of the secondary battery. A method of charging a secondary battery,
Charging the secondary battery when the temperature of the secondary battery is not more than the upper limit temperature of the rechargeable battery temperature range; and
Discharging the secondary battery when the temperature of the secondary battery is higher than the upper limit temperature and lower than the first temperature (b);
A step (c) of stopping charging and discharging of the secondary battery when the temperature of the secondary battery exceeds the first temperature;
When the temperature of the secondary battery is higher than the first temperature and lower than the second temperature in the step (c), the temperature of the secondary battery is equal to or lower than the first temperature after the step (c). When step (a) or step (b) is performed,
In the step (c), when the temperature of the secondary battery is equal to or higher than the second temperature, even if the temperature of the secondary battery falls below the second temperature after the step (c), the secondary battery A method for charging a secondary battery, comprising performing step (d) of keeping charging and discharging of the battery stopped. The method for charging a secondary battery according to claim 13,
Performing step (b) after step (a);
In the step (b), when the temperature of the secondary battery exceeds the upper limit temperature, the charging of the secondary battery is stopped and the secondary battery is charged until the charging rate of the secondary battery reaches a predetermined charging rate. Discharging the battery, the predetermined charging rate is 30% to 50%,
The secondary battery charging method, wherein the step (a) is performed again after the step (b). The method for charging a secondary battery according to claim 13,
When the temperature of the secondary battery is higher than the upper limit temperature and lower than or equal to the first temperature and the charging rate of the secondary battery is lower than the predetermined charging rate, the charging rate of the secondary battery is the predetermined rate. A charging method for a secondary battery, comprising the step of (e) charging the secondary battery until a charging rate of The method for charging a secondary battery according to claim 15,
Prior to the step (e), a step (f) of discharging the secondary battery until the charge rate of the secondary battery falls below the predetermined charge rate is performed. The method for charging a secondary battery according to any one of claims 13 to 16,
When the temperature of the secondary battery is 0 ° C. or higher and lower than the lower limit temperature of the rechargeable battery temperature range, the temperature of the secondary battery is higher than the lower limit temperature and lower than the upper limit temperature. The method further comprises a step (g) of charging the secondary battery by lowering a charge setting voltage and a charging current as compared with the above.

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