JPH04274175A - Charging method and device - Google Patents

Abstract

PURPOSE:To provide a quick charging technique without requiring a special device in a battery structure or reducing the life. CONSTITUTION:For a quick charging method, a secondary battery is charged, with a high frequency vibration given to the battery, and a quick charging device far that comprises, as illustrated, a vibration generating means to generate the high frequency vibration, a vibration transmitting means to transmit the vibration to the battery, and a current supplying means to supply a charging current to the battery.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging method and apparatus, and more particularly to a method and apparatus for rapidly charging a secondary battery.

In recent years, as various electronic devices have become smaller, lighter, and consume less power, a wide variety of portable electronic devices have been manufactured.

[0003] The power source for these portable devices is generally a "battery," which includes disposable batteries (primary batteries),
There are two types of batteries (secondary batteries) that can be reused by charging.

[0004] The advantages of primary batteries are that they are inexpensive and can be used as soon as they are obtained. On the other hand, although secondary batteries have the advantage of being reusable, they have the disadvantage that they take a long time to charge and are less responsive.

However, care must be taken when disposing of primary batteries after use; for example, if they are thrown away with general garbage, there is a risk of damaging the natural environment. For these reasons, the use of secondary batteries is socially desired, and there is a demand for the development of technology that overcomes the disadvantages of secondary batteries (long charging time).

[0006]

[Prior Art] As a conventional quick charging method, a method is known in which the charging voltage is set high and a charging current several ten times larger than the normal charging current is passed through the battery to shorten the charging time. ing.

[0007]

[Problems to be Solved by the Invention] However, in this conventional method, since the charging time is shortened by using a large charging current, (1) gas is generated inside the battery at the end of charging or during overcharging. (2) Due to the application of high voltage, the electrodes tend to deteriorate and the lifespan is shortened. There were various problems.

The present invention has been made in view of these problems, and it is an object of the present invention to provide a rapid charging technique that does not require any special modifications to the battery structure and does not shorten the battery life.

[0009]

[Means for Solving the Problems] The quick charging method of the present invention is characterized in that when charging a secondary battery, high frequency vibration is applied to the battery, and the quick charging device has a principle diagram as shown in FIG. As shown in FIG. 1, the present invention is characterized by comprising a vibration generating means for generating high-frequency vibrations, a vibration transmitting means for transmitting the vibration to a battery, and a current supply means for supplying a charging current to the battery.

0010

[Function] In the present invention, several conditions inside the battery that determine the charging speed (details will be explained in the examples) are alleviated by the excitation force of high-frequency vibration, and charging can be performed without relying on high voltage or large current. Time can be shortened.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. Basic Description (1) Structure of Secondary Battery A secondary battery is constructed by sandwiching a separator impregnated with an electrolyte between positive and negative electrodes, as shown in an example of a NiCd battery in FIG. The electrode material is a porous material (positive electrode:
Ni, negative electrode: Cd) is used, and this electrode material is impregnated with a predetermined material called an active material. (2) Charging mechanism of secondary battery For the secondary battery shown in Figure 2, apply + voltage to the positive electrode and - to the negative electrode.
When a voltage is applied, the active material [Ni(OH)
As a result of the electron [e-] being taken away from the Ni2+ group in [2], a chemical reaction as shown in the following formula (2) occurs.

[0012] Ni2+2OH− → Ni3++O
2-+OH-+H++e-... ■[e-] flows out of the battery from the electrode, but [H+] diffuses in the active material and further passes through the electrolyte (KOH) in the separator and moves. The movement continues until it encounters excess OH- groups in the active material on the negative electrode side. On the other hand, on the negative electrode side, electrons [e-
] are given, and a chemical reaction as shown in the following formula (■) occurs.

[0013] Cd2+2OH−+2e− → Cd+2OH−
...■ That is, charging is performed by accepting H+ into the negative electrode side due to an excess of hydrogen ions on the negative electrode side.

[0014] Here, the condition that determines the charging time is the time required for hydrogen ions produced at the positive electrode to reach the negative electrode.
diffusion time” and the active material in both electrodes (Ni ions,
The "moving speed" of Cd ions) and the "electric double layer" that occurs in the active material near the electrode
c double layer). The longer the diffusion time or travel time, or the stronger the electric double layer, the longer the charging time.

[0015] The inventor of the present application focused on the fact that charging time can be shortened without using high voltage and large current by relaxing such rate-determining conditions, and as a result of repeated experiments etc., the application of high frequency vibration was found to be the most effective. I discovered something. Embodiment FIGS. 3 and 4 are diagrams showing an embodiment of a charging device according to the present invention realized based on the above principle.

In FIG. 3, reference numeral 10 denotes two secondary batteries (for example, NiCd batteries, hereinafter also simply referred to as batteries), and the batteries 10 are placed inside a case 12 in which an ultrasonic oscillator 11 is embedded. It's dark. A highly electrically insulating liquid (for example, pure water) is contained inside the case 12, and most of the battery 10 is submerged in water. The case 12 and the ultrasonic oscillator 11 together constitute a so-called ultrasonic cleaner (vibration generating means, vibration transmitting means) 13.

The submerged side electrode (+,
-) are connected to each other by a conductor 14, and the electrodes (-, +) on the side that are not submerged are connected to each other by a conductor 15.
, 16 are connected to a charging circuit (current supply means) 17. The charging circuit 17 includes a DC voltage source 17a and a DC ammeter 17b, and supplies a charging current i corresponding to the voltage E of the voltage source 17a to the battery 10 via conductive wires 15 and 16. Note that the ammeter 17b is for displaying the charging current i, and is for determining the completion of charging from this displayed value. Note that the power supply for the ultrasonic oscillator 11 is not shown.

In this configuration, the charging current i from the charging circuit 17 flows into the battery 10 via the conductors 15 and 16, thereby charging the battery 10. As shown in FIG. 4, the charging current i starts to decrease immediately after the start of charging, and stabilizes to a value that hardly changes after about several tens of minutes. The charging current value during this stable period is approximately 50
It is about mA, which is significantly lower than the value at the initial stage of charging. Therefore, it takes a considerably long time to complete charging.

The reason why the charging current decreases is due to the rate-determining conditions mentioned above, namely, "diffusion time", "transfer time", and "electrical double layer". Therefore, in this embodiment, ultrasonic vibration is applied to the battery 10 during charging with the aim of relaxing the rate-determining condition. In FIG. 4, the ultrasonic transducer 11 is operated approximately 120 minutes after the start of charging. Immediately after operation, the charging current begins to increase and stabilizes at about 100 mA after about 30 minutes. This is 2 mA compared to 50 mA before applying ultrasonic vibration.
This is a two-fold increase, which can cut charging time in half.

In the experiment shown in FIG. 4, the battery 10 was made of NiC.
d is used, and a 10V/2A specification voltage source 17a is used (however, it operates at a constant voltage of 2.8V). In addition, the ultrasonic cleaner 13 has an oscillation frequency of 45 KHz,
I am using one with an oscillation power of 60W.

As described above, according to this embodiment, the ultrasonic vibrator 11 is used as a high-frequency vibration source, and charging is performed while applying the vibration excitation force to the battery 10 via the case 12 and the liquid. The conditions inside the battery that limit the charging speed can be relaxed, and high-speed charging can be achieved. Therefore, since a lower charging voltage and a smaller charging current are required than in conventional quick charging, gas generation can be reduced, making special structural improvements unnecessary, and electrode deterioration can be avoided to extend the service life.

Although ultrasonic vibrations are used in the embodiments, the present invention is not limited to this; for example, vibrations caused by AC voltage at a commercial frequency may be used. DESCRIPTION OF OTHER EMBODIMENTS The embodiments of the present invention are not limited to the above-mentioned embodiments, and various modifications as listed below are possible.

FIG. 5 shows an example in which high frequency vibrations are applied through the electrodes 20a and 20b of the battery 20. That is, the two piezoelectric transducers 22 and 23 attached to the battery holder 21 have functions as vibration generation means and vibration transmission means, and also function as holder side terminals for flowing charging current i into the battery 20. It also has functions.

The current from the current supply means 24 is applied to an electrode 20b that contacts one piezoelectric transducer 23 with low resistance.
The current flowing into the positive electrode side of the battery 20 through the battery 20 and flowing out from the negative electrode side flows back to the current supply means 24 via the other piezoelectric transducer 22 that contacts the electrode 20a with low resistance.

The piezoelectric transducers 22 and 23 are constructed by sandwiching piezoelectric ceramics (for example, PlZt) between two metal films (for example, aluminum), and
The piezoelectric ceramic vibrates due to the high-frequency electric field that acts between the electrode films. The frequency of vibration depends on the frequency of the electric field,
The strength of the vibration depends on the magnitude of the electric field.

Note that 25 and 26 are high frequency oscillators Ca and Cb for driving the piezoelectric transducers 22 and 23.
is a capacitor for blocking DC components, and L is a choke coil for blocking AC components.

Here, two piezoelectric transducers 22
, 23 are preferably aligned in vibration phase.

That is, FIG. 6 is a schematic diagram of the deformed state of the piezoelectric transducer at a certain point in time. When the phases are aligned, force can be applied to both poles of the battery 20 in the same direction. Therefore, in this example, the vibration energy of the piezoelectric transducers 22 and 23 can be transmitted to the battery 20 without waste, and the battery 20 can be greatly vibrated in its axial direction (the axis connecting the two poles). Further, since no unreasonable force (particularly force in a compressive direction) is applied to the battery 20, stress can be alleviated. Furthermore, the piezoelectric transducer 22
, 23 and the electrodes 20a, 20b while maintaining the contact force, it is possible to suppress an increase in contact resistance and prevent a decrease in charging current.

FIG. 7 shows an example in which high-frequency vibrations are transmitted to parts of the battery other than the electrodes (for example, the battery body). That is, two piezoelectric transducers 41 and 42 are brought into contact with the outer wall surface of the battery body 40, and the outer wall of the body is directly vibrated. Note that in this example, the number of piezoelectric transducers is not particularly limited to two. The number may be one, or the number may be three or more. The key is to be able to directly excite the outer wall of the body.

In this example, the battery electrodes 40a,
The connection between 40b and the terminals 44 and 45 on the current supply means 43 side requires some effort. This is because the contacts are shifted in the direction in which the battery body 40 vibrates. As a countermeasure for this, terminals 44 and 4
5 may be made flexible; for example, a spring or an elastic body such as conductive rubber may be used. Description of Application Examples Next, application products using the quick charging device of the present invention will be described.

FIG. 8 is a system configuration diagram of an applied product, and is an example of a device that automatically performs battery charging service. In FIG. 8, a money insertion section 50 determines the type and amount of the inserted coupon or coin (or prepaid card) and outputs an identification signal S1, and a battery holder 51, which also serves as a battery insertion section, stores a battery 52. It senses the injection and outputs the injection signal S2. The control unit 53 outputs the charging start command signal S3 according to the signals S1 and S2, and also outputs the charging start command signal S3.
The charging current signal S4 from 4 is monitored to determine charging completion, and the charging completion command signal S5 and battery discharge command signal S6 are
Output. The charging unit 54 charges the inserted battery 52 according to the signal S3, and also charges the battery 52 according to the signal S6.
Releases 2.

[0032] According to such a configuration, a quick charging service for a secondary battery can be performed by simply inserting a predetermined amount of money and a discharged battery, thereby simplifying the task of charging the secondary battery. Therefore, it is possible to promote the transition from primary batteries and increase the share of secondary batteries in the market.

By the way, in the above service system,
It is necessary to wait until charging of the inserted battery is completed, and it is difficult to put it into practical use unless charging is completed in an extremely short time.

FIG. 9 is an improved version of this problem, in which a fully charged battery is ejected at the same time as a battery is inserted. That is, in FIG. 9, the input battery 6
0 is transferred from the input section 61 to the discharged battery storage section 62,
It is stored together with the batteries that were already installed. At the same time, one of the batteries stored in the charged battery storage section 63 is transferred to the takeout section 64, and this charged battery 65
is taken out by the inputter.

[0035] Therefore, a charged battery can be obtained at the same time as a discharged battery is inserted, and a practically preferable rapid charging service device can be realized.

[0036]

According to the present invention, since a secondary battery is charged while applying high-frequency vibrations, it is possible to provide a rapid charging technique that does not require any special modifications to the battery structure and does not shorten its life.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention.

FIG. 2 is a schematic diagram of the internal structure of a secondary battery.

FIG. 3 is a configuration diagram of an embodiment.

FIG. 4 is a graph of charging current in one embodiment.

FIG. 5 is a configuration diagram of another embodiment.

FIG. 6 is a schematic diagram of another embodiment.

FIG. 7 is a configuration diagram of still another embodiment.

FIG. 8 is a system configuration diagram of a quick charging service device to which the present invention is applied.

FIG. 9 is an improved system configuration diagram of a quick charging service device to which the present invention is applied.

[Explanation of symbols]

10, 20: Secondary battery 13: Ultrasonic cleaner (vibration generation means, vibration transmission means) 1
7: Charging circuit (current supply means) 24, 43: Current supply means 22, 23, 41, 42: Piezoelectric transducer (vibration generation means, vibration transmission means)

Claims (5)

[Claims] 1. A charging method comprising applying high frequency vibration to a secondary battery when charging the battery. 2. A charging device comprising: vibration generation means for generating high-frequency vibrations; vibration transmission means for transmitting the vibrations to a battery; and current supply means for supplying charging current to the battery. . 3. The charging device according to claim 2, further comprising vibration transmitting means for transmitting vibrations through electrodes of the battery. 4. The charging device according to claim 2, wherein the vibration transmission path and the charging current flow path are shared. 5. The charging device according to claim 2, wherein the current supply means and the electrodes of the battery are flexibly connected, and high-frequency vibrations are transmitted to parts other than the electrodes of the battery.