JP4134873B2 - Charging method and charger for sealed alkaline storage battery - Google Patents

Description

  The present invention relates to a method for charging a sealed alkaline storage battery, and particularly when the internal pressure of the battery exceeds a predetermined specified value during charging, the electric circuit is disconnected to stop charging, and the internal pressure is equal to or less than the specified value. A charging method for a sealed alkaline storage battery having a built-in switch function that causes an electric circuit to conduct and resume charging when the voltage drops to a low level, and is applied to the quick charging method that terminates charging in a short time of less than one hour It relates to the charger.

  Sealed alkaline storage batteries are excellent in performance after being discharged and withstand overcharge, and are easy to use for general users. For portable electronic devices such as mobile phones, small power tools, and small personal computers. Widely used as a power source.

  The charging of the sealed alkaline storage battery is a charging that takes about 1 hour to complete the charging, although it is a quick charging so far, and the vent operates when the internal pressure of the battery abnormally rises during the charging (abnormal pressure increase) However, the battery temperature rarely rises above the upper limit of the temperature preferable for the battery (abnormal temperature rise), and therefore, even if charging is repeated, no significant performance degradation was observed and no particular problem was found. However, in recent years, there has been an increasing demand for unprecedented rapid charging that completes charging in an extremely short time of 30 to 15 minutes. When such rapid charging is performed, the abnormal pressure increase or abnormal temperature increase frequently occurs, and there is a risk that the battery performance may be significantly deteriorated due to the consumption of the electrolyte or the deterioration of the battery constituent material. It has been extremely difficult to meet the demands for the battery with the conventional structure.

As a measure corresponding to a request for quick charging that has not been made in the past, Patent Document 1 proposes that a sealed battery has the pressure switch function. According to the proposal, by operating the pressure switch function, the battery temperature does not rise beyond the upper limit of the temperature range preferable for the battery even when a quick charge is performed to complete the charge in 30 to 15 minutes. Can control. (See Patent Document 1)
WO 02/35618 A1 Publication (FIG.2A, FIG.2B)

  The sealed alkaline storage battery employs a method in which the capacity of the negative electrode is made larger than that of the positive electrode, and oxygen generated at the positive electrode at the end of charging is absorbed by the negative electrode. This method is referred to as an oxygen cycle method, and by adopting this method, in principle, the battery is not destroyed even if overcharging is performed. However, the oxygen absorption reaction by the negative electrode is an exothermic reaction, and there is a possibility that the internal temperature of the battery is raised and the battery constituent material is deteriorated. Moreover, the generation of oxygen from the positive electrode due to overcharging may increase the internal pressure of the battery and push out the electrolyte from the electrode or separator, leading to a liquid dripping phenomenon of the electrode or separator. In addition, the termination of charging too early leads to insufficient charging. Therefore, appropriately determining the end of charging of the sealed alkaline storage battery is extremely important for exerting the original performance of the storage battery and maintaining the performance of the storage battery for a long period of time.

  Patent Document 1 describes a charging method for charging a storage battery having the pressure switch function with a constant voltage. In this charging method, as a method for determining the end point of charging of the alkaline storage battery, a -ΔV charge control method (a charging end determination method in which charging is terminated by detecting -ΔV) that has been widely used in the past cannot be adopted. .

  The simplest method of determining the charging end point is a method of determining by the elapsed time from the start of charging. However, according to this method, the charge acceptance rate depends on the ambient temperature when charging (the charge acceptance rate here is the ratio of the discharge capacity after the charge to the rated capacity of the battery. This means the discharge capacity inherently possessed by a fully charged battery. Here, it is defined as the discharge capacity obtained when a fully charged battery is discharged at a rate of 0.2 ItA at room temperature.) (Charge efficiency here means the ratio of the discharge capacity to the charge electricity amount after the charge) has a drawback that it varies greatly depending on the ambient temperature.

  Patent Document 1 proposes a method in which a strain gauge that controls expansion and deformation of an outer layer can is attached to the surface of a storage battery, and charging is terminated when the indicated value of the gauge reaches a specified value. Since the strain gauge requires a strain gauge, the structure of the charger is complicated and expensive.

  The present invention has been made in view of the disadvantages of the above-described prior art, and in the method for rapidly charging a sealed alkaline storage battery in a short time, it is possible to suppress the occurrence of insufficient charging and overcharging as much as possible. It is intended to provide a charging method for determining the timing of charging termination to be performed by a simple method.

In the present invention, as a result of intensive studies, the charging acceptance rate and charging efficiency of an alkaline storage battery, the ratio between the charging current and the rated capacity of the battery (A _C / C _N ), and the ratio between the charging current and the peak value of the charging current (A _C / A _CM ), the two ratios can be applied as an index for determining the charging termination time point, and the above two ratios can be used as an index for determining the charging termination time point. This is based on the finding that the charge acceptance rate and the charging efficiency are less affected by the ambient temperature during charging compared to the method in which charging is completed in time.

This invention solves the said subject by making the charging method of a sealed alkaline storage battery into the following structure.
(1) The method for charging a sealed alkaline storage battery according to the present invention is such that when the internal pressure of the battery exceeds a predetermined specified value during charging, the electric circuit is disconnected to stop charging, and the internal pressure falls below the specified value. Charging method for rapidly charging a sealed alkaline storage battery in a short time with a built-in pressure switch function for turning on an electric circuit and restarting charging, and a constant voltage of 1.5 to 1.7 V per cell The ratio (A _C / C _N ) between the charging current (A _C ) and the rated capacity (C _N ) of the battery is within a range of 1 to 2 (mA / mAh). This is a method for charging a sealed alkaline storage battery that completes charging when it reaches a specified value. The charging current (A _C ) here refers to a charging current value that flows when the charging circuit is ON, not when the pressure switch is operated and the charging circuit is OFF.
(2) The method for charging a sealed alkaline storage battery according to the present invention is such that when the internal pressure of the battery exceeds a predetermined specified value during charging, the electric circuit is disconnected to stop charging, and the internal pressure falls below the specified value. Charging method for rapidly charging a sealed alkaline storage battery in a short time with a built-in pressure switch function for turning on an electric circuit and restarting charging, and a constant voltage of 1.5 to 1.7 V per cell Is applied, and the ratio of charging current and peak charging current (peak value of charging current) (A _C / A _CM ) reaches a predetermined specified ratio in the range of 0.25 to 0.6. This is a method for charging a sealed alkaline storage battery that completes charging at the time when the battery is discharged.
(3) The battery charger of the sealed alkaline storage battery according to the present invention stops the charging by cutting the electric circuit when the internal pressure of the battery exceeds a predetermined specified value during charging, and the internal pressure falls below the specified value. Is a battery charger for a sealed alkaline storage battery that has a built-in pressure switch function that makes an electric circuit conductive and resumes charging, and is charged by applying a constant voltage of 1.5 to 1.7 V per cell. a function, a function to record the rated capacity of the function and the battery for detecting a charge current or a function of recording a peak value of the function as the charging current for detecting the charging current, the a _C / C _N or, A battery charger for a sealed alkaline storage battery having a function of detecting that A _C / A _CM has reached a predetermined value and terminating charging.

  According to the method for charging a sealed alkaline storage battery according to the present invention, when the internal pressure of the battery exceeds a predetermined specified value during charging, the electric circuit is disconnected to stop charging, and the internal pressure falls below the specified value. When charging a sealed alkaline storage battery in a short period of time with a built-in pressure switch function that sometimes turns on the electrical circuit and resumes charging, it is a simple method and minimizes shortage and overcharging. Charging can be terminated. (Claim 1, Claim 2)

  The battery charger for the sealed alkaline storage battery according to the present invention disconnects the electric circuit when the internal pressure of the battery exceeds a predetermined specified value during charging and stops charging, and when the internal pressure falls below the specified value. When charging a sealed alkaline storage battery in a short period of time with a built-in pressure switch function that turns on the electric circuit and restarts charging, it is possible to suppress the shortage and overcharging as much as possible with a simple configuration. It is a charger for a sealed alkaline storage battery. (Claim 3)

  A charging method according to the present invention is a charging method for charging a sealed alkaline storage battery having the pressure switch function by constant voltage charging, and charging a battery in a fully discharged state in a short time of 30 to 15 minutes. It is a quick charging method that can complete.

  The configuration of the pressure switch is not particularly limited, but the pressure switch described in Patent Document 1 can be applied as an example. Specifically, a sealed alkaline storage battery 11 having a built-in pressure switch 12 as shown in FIG. As shown in FIG. 1, the pressure switch 12 has an electrically insulating sealing member 1 and a ring-shaped metal plate 5 disposed at the open end (upper part of the figure) of a cylindrical battery case 13, and the center of the sealing member 1. A cylindrical through hole 2 is provided in the portion, and a connecting member 3 constituting an electric circuit connecting the electrode (positive electrode) 10 and the cap-shaped terminal 6 is passed through the through hole 2. The battery is hermetically sealed by bringing the inner wall of the through-hole 2 and the side wall of the connecting member 3, the outer peripheral surface of the sealing member 1, the inner wall of the battery case 13, and the outer peripheral wall of the ring-shaped metal plate 5 and the sealing member 1, respectively. Sealed. The sealing member 1 is flexible, and the connecting member 3 can be moved in the vertical direction in the figure, whereas the ring-shaped metal plate 5 is fixed in position.

  The electrode 10 and the connection member 3 are connected via a tab terminal 9. A ring-shaped metal connection piece 4 is bonded to the upper portion of the side wall of the connection member 3, and a cap-shaped terminal 6 is bonded to the outer surface (the upper surface in the drawing) of the ring-shaped metal plate 5. An elastic body 7 is inserted into a space surrounded by the ring-shaped metal plate 5, and the connecting member 3 is pressed inward (downward in the figure) by the pressing force of the elastic body 7.

  When the internal pressure of the battery is less than or equal to the specified value, the magnitude of the pressing force of the elastic body 7 exceeds the magnitude of the internal pressure of the battery, so that the connecting member 3 is pushed inward (downward in the figure) of the battery. As shown in FIG. 5, the lower surface of the connection piece 4 comes into contact with the upper surface of the ring-shaped metal plate 5, and the circuit connecting the electrode 10 and the terminal 6 becomes conductive. When the internal pressure of the battery exceeds a specified value, the internal pressure of the battery exceeds the pressing force of the elastic body 28, so that the connecting member 3 is pressed outward (upward in the figure) of the battery, and the connecting piece 4 and the ring-shaped metal The board 5 is separated and the electric circuit is cut off.

  In the present invention, it is desirable to set the charging voltage within the range of 1.5 to 1.7V. If the charging voltage is less than 1.5V, the progress of charging is slow and there is a possibility that it takes a long time for charging. When the charging voltage exceeds 1.7 V, oxygen generation occurs at the positive electrode during charging, and hydrogen generation occurs at the negative electrode, and in addition to the battery temperature rising beyond the preferred temperature range, It operates and there is a possibility that it cannot be charged in a short time.

In the present invention, the A _C / C _N at the time of charging is 1~2 (mA / mAh), and more preferably be in the range of 1.3~1.7 (A / Ah), a predetermined Stop charging when the value is reached. Becomes overcharging is less than A _C / C _N is 1, there is a possibility of causing deterioration of battery performance by repeating the charging. Also, A _C / C _N becomes insufficient charging exceeds 2, there is a possibility that not Ikase performance have original battery sufficiently.

In the present invention, when the A _C / A _CM at the time of charging is within a range of 0.25 to 0.6, more preferably 0.25 to 0.5, and reaches a predetermined value. Stop charging. If A _C / A _CM is less than 0.25, the battery is overcharged, and the battery performance may be deteriorated by repeating the charge. Further, if A _C / A _CM exceeds 0.6, charging is insufficient, and there is a possibility that the performance inherent in the battery cannot be fully utilized.

Hereinafter, the details of the present invention will be described with reference to an embodiment to which a constant voltage charging mode is applied.
(First Embodiment: Charge censored at the time A _C / C _N has reached the predetermined value)
(Example 1)
A sealed nickel-metal hydride storage battery having a rated capacity of 2000 mAh and an AA size (AA) having a nickel electrode as a positive electrode and a hydrogen storage alloy electrode as a negative electrode, comprising the pressure switch shown in FIG. A sealed nickel-metal hydride storage battery having an operating pressure of 2.4 megapascals (MPa) was produced.

  Five storage batteries were prepared, and a temperature sensor for measuring the battery temperature was attached to the surface of each battery. After initializing the battery by a prescribed method, it was charged for 6 hours at a charging current of 0.2 ItA at an ambient temperature of 20 ° C., left for 1 hour, and then discharged at a discharge current of 0.2 ItA at the same ambient temperature. The voltage was discharged at 1.0V. The discharge capacity obtained by the discharge was defined as the rated capacity A (mAh) of Example 1.

The battery after the discharge was charged at a constant voltage of 1.65 V at an ambient temperature of 20 ° C. Charging method according ten specimen cell to an embodiment of the present invention, specifically stops charging when it reaches the A _C / C _N within 1.3 (mA / mAh). After leaving the battery for 2 hours, the battery was discharged at an ambient temperature of 20 ° C. with a discharge current of 0.2 ItA and a discharge end voltage of 1.0 V. The discharge capacity obtained by the discharge was defined as B (mAh), and the ratio B / A (%) of B (mAh) to A (mAh) was defined as the charge acceptance rate when constant voltage charging was performed. Moreover, the charging current during charging was monitored, and this was integrated to obtain the amount of charged electricity C (mAh). The ratio B / C (%) of the discharge capacity B (mAh) to the charge electricity amount C (mAh) was calculated, and the calculated value was defined as the charge efficiency.

The battery after the discharge was charged at a constant voltage of 1.65 V at different temperatures of ambient temperature 5 ° C. and 35 ° C. Charging method according ten specimen cell to an embodiment of the present invention, specifically stops charging when it reaches the A _C / C _N within 1.3 (mA / mAh). After stopping the charge, the battery was transferred to an atmosphere at an ambient temperature of 20 ° C. and left for 2 hours, and then discharged at a discharge current of 0.2 ItA at a discharge current of 1.0 V at the same ambient temperature.

(Example 2 to Example 4)
A battery having the same configuration as in Example 1 was charged at a constant voltage of 1.65 V at an ambient temperature of 20 ° C. However, A _C / C _N, respectively abort charging when it reaches the 1,1.7,2 (mA / mAh), as in Example 1, at ambient temperature 20 ° C. After standing for 1 hour after charging stop The battery was discharged at a discharge current of 0.2 ItA and a final discharge voltage of 1.0V. The charge acceptance rate and the charge efficiency were determined in the same manner as in Example 1. The charging methods are referred to as Example 2, Example 3, and Example 4, respectively.

(Comparative Example 1 and Comparative Example 2)
The battery having the same structure as in Example 1, A _C / C _N is, of cutting the charging when it reaches the respective 0.8,2.3 (mA / mAh), in the same manner as in Example 1 Charging acceptance rate and charging efficiency were calculated. The charging methods are referred to as Comparative Example 1 and Comparative Example 2, respectively.

  FIG. 2 shows the charge acceptance rates of Examples 1 to 4, Comparative Example 1, and Comparative Example 2, and FIG. 3 shows the charging efficiencies of Examples 1 to 4, Comparative Example 1, and Comparative Example 2.

  As shown in FIG. 2, compared to Examples 1 to 4 and Comparative Example 1, Comparative Example 2 has a lower charge acceptance rate. Since both the example and the comparative example are charged at a constant voltage of 1.65 V, the charging time is 14 to 20 in the case of Example 1 to Example 4 while the charging current shows the same temporal transition. In the case of Comparative Example 1, the charging time is 25 minutes, whereas in Comparative Example 2, the charging time is about 10 minutes, which is short. In the case of Comparative Example 2, it is considered that charging was insufficient because the charging time was short.

In addition, as shown in FIG. 3, Comparative Example 1 has lower charging efficiency than Examples 1 to 4 and Comparative Example 2. In the case of Comparative Example 1, it is considered that the charging efficiency is low because the charging time is long as described above, and oxygen generation from the positive electrode at the end of charging is active (a state in which side reactions are actively occurring). .
From the results shown in FIGS. 2 and 3, the A _C / C _N is good 1~2 (mA / mAh), it is understood that more preferably 1.3~1.7 (mA / mAh).

(Second embodiment of the present invention: when A _C / A _CM reaches a specified value, charging is terminated)
(Example 5)
Charging was terminated when the ratio of charging current to peak charging current (A _C / A _CM ) in Example 1 reached 0.4. Others were the same as in Example 1. This charging method is referred to as Example 7.

(Example 6 to Example 8)
In Example 7, the charging was terminated when the ratio of charging current to peak charging current (A _C / A _CM ) reached 0.25, 0.5, and 0.6, respectively. Otherwise, it was the same as Example 5. The charging methods are referred to as Example 6, Example 7, and Example 8, respectively.

(Comparative Example 3, Comparative Example 4)
In Example 7, the charging was terminated when the ratio of charging current to peak charging current (A _C / A _CM ) reached 0.2 and 0.7, respectively. Otherwise, it was the same as Example 7. The charging methods are referred to as Comparative Example 3 and Comparative Example 4, respectively.

  FIG. 4 shows the charge acceptance rates of Examples 5 to 8, Comparative Example 3, and Comparative Example 4, and FIG. 5 shows the charging efficiencies of Examples 5 to 8, Comparative Example 3, and Comparative Example 4.

  As shown in FIG. 4, compared to Examples 1 to 4 and Comparative Example 4, Comparative Example 3 has a lower charge acceptance rate. Since both the example and the comparative example are charged at a constant voltage of 1.65 V, the charging time is 14 to 20 in the case of Example 1 to Example 4 while the charging current shows the same temporal transition. In the case of Comparative Example 4, the charging time is 25 minutes, whereas in Comparative Example 3, the charging time is about 10 minutes, which is short. In the case of Comparative Example 3, it is considered that charging was insufficient because the charging time was short.

Further, as shown in FIG. 5, Comparative Example 4 has lower charging efficiency than Examples 1 to 4 and Comparative Example 3. In the case of Comparative Example 4, the charging time is long as described above, and it is considered that the charging efficiency was lowered because oxygen generation from the positive electrode at the end of charging became active (a state in which side reactions were actively occurring). .
From the results shown in FIGS. 4 and 5, it is understood that A _C / A _CM is preferably 0.25 to 0.6 and more preferably 0.25 to 0.5.

(Comparison between the embodiment of the present invention and a charging method that stops charging in a certain time)
(Example 9, Example 10)
A battery having the same configuration as in Example 1 was subjected to the same test as in Example 1. However, the ambient temperature during charging was carried out at three temperatures of 20 ° C., 5 ° C. and 35 ° C. This example is referred to as Example 9.
A battery having the same configuration as in Example 1 was subjected to the same test as in Example 7. However, the ambient temperature during charging was carried out at three temperatures of 20 ° C., 5 ° C. and 35 ° C. This example is referred to as Example 10.
(Comparative Example 5 and Comparative Example 6)
Five storage batteries having the same configuration as in Example 1 were subjected to the same test as in Example 9. However, the charging was cut off when 15 minutes had elapsed after the start of charging. This example is referred to as Comparative Example 5.
Five storage batteries having the same configuration as in Example 1 were subjected to the same test as in Example 9. However, the charging was stopped when 20 minutes passed after the start of charging. This example is referred to as Comparative Example 6.

  FIGS. 6 and 7 show the charge test results according to Example 9, Example 10, Comparative Example 5, and Comparative Example 6 at ambient temperatures of 5 ° C., 20 ° C., and 35 ° C.

As shown in FIG. 6 and FIG. 7, according to the charging method of the present invention, the charge acceptance rate even when the ambient temperature at the time of charging changes, as compared with the comparative example in which the charging is terminated after the elapse of a certain time after the start of charging, Changes in charging efficiency are small and are not easily affected by ambient temperature. On the other hand, in Comparative Example 5, the charge acceptance rate is low at 5 ° C. as shown in FIG. In the case of the comparative example 5, it is considered that charging was insufficient due to a low charging current due to a low ambient temperature during charging. Moreover, in the case of the comparative example 7, as shown in FIG. 7, the charging efficiency in the ambient temperature 20 degreeC and 35 degreeC at the time of charge is low. In the case of Comparative Example 7, since the charging time was set to be long, the charging was continued even after the battery temperature rose due to charging, so the charging efficiency was low because the ratio of side reactions such as oxygen gas generation from the positive electrode increased. It is thought that it became. On the other hand, in the case of the ninth and tenth embodiments, the charging time is determined depending on the ambient temperature at the time of charging by using A _C / _CN or A _C / A _CM as an index for determining the charging end point. The charge acceptance rate and charge efficiency are considered to be less affected by the ambient temperature during charging.

The charger according to the present invention is a charger for charging a sealed alkaline storage battery at a constant voltage, and includes an electric circuit for detecting a charging current and a memory circuit for recording a rated capacity of the input battery, and A switch function is provided that disconnects the charging circuit when the ratio between the charging current (A _C ) and the rated capacity (C _N ) of the battery reaches a preset value. By setting it as the charger of this structure, it can be set as the charger suitable for the charging method of this invention.

A charger according to the present invention is a charger for charging a sealed alkaline storage battery at a constant voltage, and includes an electric circuit for detecting a charging current and a memory circuit for recording a peak charging current, and a charging current (A _C ) And the peak charging current (A _CM ) have a switch function that disconnects the charging circuit when the ratio reaches a preset ratio. By setting it as the charger of this structure, it can be set as the charger suitable for the charging method of this invention.

It is a figure which shows typically the principal part structure of a sealed alkaline storage battery with a pressure switch function. It is a graph which shows the relationship between the ratio ( _AC / _CN ) of the charging current and rated capacity at the time of charge termination, and a charge acceptance rate. It is a graph which shows the relationship between the ratio (A _C / C _N ) of the charging current and the rated capacity at the time of charging termination, and the charging efficiency. It is a graph which shows the relationship between the ratio (A _C / A _CM ) of the charging current and the peak charging current at the time of charging termination, and the charging acceptance rate. It is a graph which shows the relationship between the ratio (A _C / A _CM ) of the charging current and peak charging current at the time of charging termination, and the charging efficiency. It is a graph which shows the relationship between the ambient temperature at the time of charge, and a charge acceptance rate. It is a graph which shows the relationship between the ambient temperature at the time of charge, and charging efficiency.

Explanation of symbols

11 Sealed alkaline storage battery with built-in pressure switch 12 Pressure switch

Claims (3)

Pressure switch function that stops the charging by disconnecting the electric circuit when the internal pressure of the battery exceeds a predetermined value during charging, and resumes the charging by making the electric circuit conductive when the internal pressure falls below the specified value Is a charging method for charging a sealed alkaline storage battery with a constant voltage of 1.5 to 1.7 V per cell, the charging current (A _C ) and the rated capacity (C _N ) of the battery A method for charging a sealed alkaline storage battery in which charging is stopped when the ratio (A _C / C _N ) reaches a predetermined specified value within a range of 1 to 2 (mA / mAh). Pressure switch function that stops the charging by disconnecting the electric circuit when the internal pressure of the battery exceeds a predetermined value during charging, and resumes the charging by making the electric circuit conductive when the internal pressure falls below the specified value Is a charging method for charging a sealed alkaline storage battery with a constant voltage of 1.5 to 1.7 V per cell , and the ratio of charging current to peak charging current (A _C / A _CM ) is , A charging method for a sealed alkaline storage battery that terminates charging when a predetermined specified value within a range of 0.25 to 0.6 is reached. Pressure switch function that stops the charging by disconnecting the electric circuit when the internal pressure of the battery exceeds a predetermined value during charging, and resumes the charging by making the electric circuit conductive when the internal pressure falls below the specified value Is a battery charger for a sealed alkaline storage battery, which has a function of charging by applying a constant voltage of 1.5 to 1.7 V per cell , a function of detecting a charging current , and a charging current. When the ratio between the battery and the rated capacity of the battery (A _C / C _N ) or the ratio between the charging current and the peak charging current (A _C / A _CM ) reaches a predetermined value, charging is performed. Sealed alkaline storage battery charger with the ability to terminate.

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