JP2905582B2 - Rechargeable battery device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rechargeable battery device capable of quick charging, and more particularly to a rechargeable battery device having a charge control function therein.

[Conventional technology]

With the development of portable devices, primary batteries and secondary batteries are used as power sources for radios, cassette tape recorders with radios, portable VTRs, electronic devices such as portable computers, communication devices such as mobile phones, and power devices such as portable electric tools. Batteries are becoming widely used. In particular, the use of secondary batteries has increased remarkably in recent years.

In particular, there is a growing demand for light-weight, small-sized, high-capacity rechargeable battery devices that can be rapidly charged in portable devices, but in detachable rechargeable battery devices used in portable devices, charging devices other than dedicated charging devices are used. If the battery device is overcharged beyond the appropriate charging conditions as the capacity of the battery device increases, the inside of the rechargeable battery device will be Had a protection function against overcharging. However, when such a safety device works, the battery is normally overcharged beyond the proper charging conditions, and the performance of the battery device is degraded even if a serious safety trouble is avoided. In addition, it was sometimes impossible to use it later.

[Problems to be solved by the invention]

Generally, in a battery, when overcharging is performed beyond proper charging conditions, gas is generated along with decomposition of the electrolytic solution. In open or exhausted batteries, the evolved gas can escape, but the electrodes are somewhat damaged as a result.

On the other hand, in a sealed battery, the gas pressure increases inside, causing an explosion accident. Some sealed batteries have a safety valve to prevent gas pressure from rising due to overcharge.However, batteries with these safety valves can reliably release gas. In some cases, there is a problem in terms of reliability. In addition, since the highly corrosive gas is released by the operation of the safety valve, there is a disadvantage in that the device incorporating the battery is corroded. Further, in the worst case, a short circuit was caused inside the battery, and the battery sometimes burst. Therefore, there is a need for a device that prevents the battery from continuing to charge beyond normal charging conditions.

For secondary batteries that are generally commercially available, connect a thermostat or temperature fuse, etc., in series with the battery, detect the heat generated by the battery when overcharged beyond appropriate charging conditions, and shut off the charging circuit. Is trying to solve the above problems.

However, in a device such as a thermostat or a temperature fuse that detects heat generated at the time of overcharging and shuts off the charging circuit, the battery has already exceeded the appropriate charging conditions and overcharging has progressed. In addition to deterioration, the battery may have an abnormal state such as liquid leakage or rupture.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and to provide a secondary battery inside the rechargeable battery device even when misused such as when the rechargeable battery device is charged by a charging device other than the dedicated charging device. The rechargeable battery device itself controls charging properly, protects the internal rechargeable battery from overcharging, and allows repeated use without overcharging the internal rechargeable battery. Accordingly, it is an object of the present invention to provide a rechargeable battery device capable of quick charging.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a non-aqueous rechargeable battery using a material capable of intercalating cations into gaps of a molecular structure in one of a positive electrode and a negative electrode, or both a positive electrode and a negative electrode. In the battery device, a secondary battery that can be charged by an external charging device, a switching unit having a parasitic diode therein and inserted in series in a discharge / charge circuit of the secondary battery, and a terminal voltage of the secondary battery A voltage detecting means for detecting the voltage, based on the detection result of the voltage detecting means, when the voltage between the terminals of the secondary battery at the start of charging by the external charging device is lower than the first off-voltage, The switch means is turned on to charge the secondary battery based on the control of the external charging device. After the terminal voltage of the secondary battery reaches the first off-voltage, the switching means is turned on. The secondary battery is pulse-charged by repeatedly turning on / off the charging current from the external charging device, and the terminal voltage of the secondary battery when the pulse charging is off is the first voltage. Charge control means for terminating the pulse charging when a second off-state voltage higher than the off-state voltage is exceeded.

That is, the present invention controls on / off of a charging current from an external charging device by turning on / off a switching means inserted in series in a charging / discharging circuit of a secondary battery. Although it is preferable to detect the voltage between the terminals of the secondary battery when the battery is off, the detection of the coarse charge amount may be performed by detecting the voltage between the terminals of the secondary battery when the charging current is on. First, the secondary battery is charged based on the control of the external charging device, the timing of transition to pulse charging is determined by measuring the voltage between the terminals of the secondary battery being charged, and the timing of ending the pulse charging is By making a determination based on the measurement result of the voltage between the terminals of the secondary battery when the charging current is off, it is possible to appropriately control the charge amount. In particular, the present invention has made possible a detachable rechargeable battery device, which is a compact rechargeable battery device having built-in charge control means.

In the present invention, as the control pattern of the charging current, when the voltage between the terminals of the secondary battery at the start of charging by the external charging device is smaller than the first off-voltage (V _off ), the charging / discharging circuit The switch means inserted in series is turned on to perform charging based on the control of the external charging device. After the voltage between the terminals of the secondary battery reaches the first off voltage (V _off ), the switch means is repeatedly turned on. Pulse charging is performed by turning off and intermitting the charging current, and the voltage between the terminals of the secondary battery when the pulse charging is off is changed to the second off voltage (V
^{When PC} _off ) or more, the pulse charging ends.

Further in the present invention, no problem even when an additional function of the terminal voltage of the secondary battery to resume the second off-voltage (V ^PC _on) falls below the pulse charging for pulse charging start. In this case, when the inter-terminal voltage of the secondary battery at the time of the pulse charging is turned off becomes equal to or higher than the second off-voltage (V ^PC _off ), the pulse charging is stopped again. Further, in the present invention, a function of stopping the pulse charging when the interruption and the resumption of the pulse charging are repeated n times may be added. It is desirable that the on time (t _on ) of the switch means is fixed at 1 μsec or more and 1 sec or less, but the pulse current interruption time, that is, the off time (t _off ) does not necessarily have to be fixed.
It suffices if the measurement of the voltage between the terminals of the secondary battery and the switching of the switch means during the interruption of the pulse current can be performed, but the interruption time (t _off ) of the pulse current is usually required to be 1 μsec or more. Further, the duty ratio {Q = t _on / (t _on + t _off )}
Is 0 <Q <1, and in order to shorten the charging time, it is preferable to set the value as close to 1 as possible. However, there is an appropriate range according to the characteristics of the secondary battery. However,
The duty ratio (Q) does not necessarily need to be kept constant, and the effect of shortening the charging time is inferior to the case where the duty ratio (Q) is kept constant at an optimum value.
Even if is not kept constant, it is possible to control charging sufficiently efficiently.

When charging the secondary battery controlled by the external charging device and then performing charging control for changing the duty ratio (Q) in the intermittent charging current from the external charging device to the secondary battery, a pulse is generated. No circuit is required, and the amount of charge can be easily controlled. In particular, when the charge control means is mounted inside the rechargeable battery device, the size can be reduced, which is advantageous. That is, when the voltage between the terminals of the secondary battery at the start of charging by the external charging device is lower than the first off-voltage (V _off ), the switch means inserted in series in the charging / discharging circuit is turned on to turn on the external device. The discharge controlled by the charging device is performed on the secondary battery, and the voltage between the terminals of the secondary battery becomes the first off voltage (V _off ).
At this point, the charging control means controls the on / off of the switch means, interrupts the charging current after the charging current has flowed from the external charging device for a certain fixed on-time (t _on ), and returns to the first state again. of the off voltage (V _off) falls below a lower first on-voltage (V _on) than passing a charging current, the terminal voltage of the secondary battery becomes the first off-voltage (V _off) or constant By repeatedly continuing to interrupt the charging current after the charging current has flowed for more than the on time (t _on ), pulse charging in which the off time (t _off ) changes according to the charged amount can be realized, and proper charging can be achieved. Volume control is possible. In this case, the charging of the secondary battery is not sufficient, and when the charging current is cut off, the terminal voltage of the secondary battery immediately drops due to a decrease in the voltage between the terminals of the secondary battery due to the charging overvoltage of the secondary battery. The difference between the first off-voltage and the on-voltage (V _off -V _on ) may be 0.1 V or less so that the on-voltage (V _on ) or less and the discharge proceeds rapidly to an appropriate charge amount. Preferably, even if the charging current is cut off and the terminal voltage of the secondary battery decreases due to the overvoltage of the secondary battery, the terminal voltage of the secondary battery does not immediately fall below the first on-voltage (V _on ). When the charging proceeds to the charging state, the off time (t _off ) becomes sharply larger than the value at the start of the pulse charging, and the charging is stopped.

In particular, when the charging device according to the present invention incorporates, as an electrode material, a secondary battery using a material such as chalcogenite or a carbonaceous material in which the potential of the electrode changes monotonously with the progress of charging, the charging device is used. The charge amount of the battery can be kept constant without excess or shortage. In other words, non-aqueous secondary batteries that use a material that can intercalate cations into the gaps in the molecular structure for either the positive electrode or the negative electrode, or for both the positive electrode and the negative electrode, require a chemical reaction on the surface of the electrode. Unlike many water-based batteries that are released and charged by the battery, the temperature change of the electrode potential is small and the electrode potential changes monotonically according to the amount of charge. The secondary battery according to the present invention, which can detect the charge amount of the battery well and controls the charge amount at the end of charging by detecting the open-circuit voltage between the terminals of the battery during an off time that is very short compared to the off time Useful as a battery.

Further, JP-55-13613, JP-Sho 62-90863, JP-rechargeable battery of nonaqueous disclosed in JP 63-299056 Laid, i.e., A _x M _y N _z O ₂ (A represents at least one kind of alkali metal, N represents at least one kind of non-transition metal, and x, y, and z are respectively 0.05 ≦ x ≦ 1.10, 0.85 ≦ y ≦
1.00, O ≦ z ≦ 0.10. The non-aqueous secondary battery which can be repeatedly charged and discharged using the positive electrode active material represented by the formula (1) and the carbonaceous material as the negative electrode active material is particularly useful as the secondary battery according to the present invention.

Note in the composite oxide represented by the general formula A _x M _y N _z O ₂ is used as a positive Gokuomokatsu material, M represents a kind at least a transition metal, N is the representative of the kind at least the non-transition metals.
M is not particularly limited, but as an example,
Co, Ni, Fe, Mn, V, Mo and the like can be mentioned. Similarly, N is not particularly limited, but Al, In, Sn and the like can be mentioned.

The switch means in the present invention is preferably a voltage-driven switch in order to reduce power loss and reduce power consumption in a normal use state. As a device satisfying this condition, a field-effect transistor (FET) has a preferable condition. Among them, the use of a MOS FET having a parasitic diode inside the device significantly simplifies the circuit and reduces the size. Found that it can be That is, the MOS FE
By using the parasitic diode inside T as a part of the discharge circuit of the secondary battery, the discharge circuit in the rechargeable battery device can be omitted, and the two-terminal component as in the conventional rechargeable battery device. And a third terminal or the like for controlling the charge control device in the battery device is not necessarily required.

Therefore, as a result of studying the MOS FET used as the switching means, it is preferable that the drain-source ON resistance (R _{DS (on)} ) is smaller as the MOS FET, and the drain-source ON resistance (R _{DS (on)} ) Has to be equal to or smaller than the internal resistance of the secondary battery. Of course, MOS FETs can be used in parallel. In this case, the drain and
It is necessary that the combined resistance value of the source-to-source on-resistance (R _{DS (on)} ) is equal to or smaller than the internal resistance of the secondary battery. If the drain-source on-resistance (R _{DS (on)} ) of the MOS FET is higher than the internal resistance of the secondary battery, not only will the power loss due to the MOS FET increase, but also as a result, Temperature distribution is undesirably large.

Note that as a switch means, a device having a parasitic diode inside is an MO having a parasitic diode inside.
By using a parasitic diode as a part of the discharge circuit, as in the case of the SFET, the circuit in the rechargeable battery device can be simplified, as in the case of the MOS FET.

By the way, the electronic circuit used as charge control means
Although it can be constituted by a bipolar IC, a MOS IC, a CMOS IC, a Bi-MOS IC, a hybrid IC, or the like, it is preferable that the current consumption is small, and it is desirable that the current consumption is at least smaller than the self-discharge current of the secondary battery. In particular, as a detachable rechargeable battery device, if the rechargeable battery is stored in a charged state, it can be left alone without using it, and the remaining capacity of the rechargeable battery device will be significantly shortened in a short time Hard to bear use.

[Action]

According to the present invention, it is possible to provide a rechargeable battery device that can be repeatedly used with a very simple configuration and can be charged under normal charging conditions even when charged by a charging device other than the dedicated charging device. it can.

〔Example〕

Hereinafter, embodiments of the rechargeable battery device according to the present invention will be described with reference to the drawings.

FIG. 1 shows a block diagram of the present invention. As shown in FIG. 1, the rechargeable battery device 1 includes a secondary battery 2, a voltage detection unit 3, a charge control unit 4, and a switch unit 5. As shown in FIG. 1, the load or charger 6 is connected to the rechargeable battery device 1. The battery 2 is composed of a single battery or a battery pack connected in series or in parallel. The voltage detection unit 3 and the charge control unit 4 can be configured by a comparator, a reference voltage circuit, a pulse transmission circuit, and the like.

Next, a case where the pulse transmission circuit is not provided inside the rechargeable battery device will be specifically described with reference to the drawings.
In this case, following the charging controlled by the external charging device, the charging current from the external charging device is intermittently switched to set the duty ratio {Q = t _on / (t _on + t _off )} to charge the secondary battery. Varies according to quantity. FIG. 2 shows the on-time (t
One example of a circuit that can realize pulse charging in which the _on time is constant and the off time (t _off ) changes according to the charged amount is shown. In the rechargeable battery device 1 shown in FIG. 2, a Schmitt circuit is configured by a comparator 8 that compares a reference voltage set by a reference voltage circuit 7 with a voltage between terminals of the secondary battery 2, and a first off-voltage (V _off ) and the first ON voltage (V _on ) are set. That is, although the hysteresis of the comparator 8 can be set by the value of the resistor 9, the width of the hysteresis of the comparator 8 (V
_off -V _on ) is desirably set to about 0.1 V or less. That is, if the charging is not sufficiently progressing and the charging current is cut off, the charging overvoltage (η = γ _in · I ^PC , γ _in ; internal resistance of the secondary battery 2, I ^PC ; pulse charging current) When the voltage between the terminals of the secondary battery 2 decreases immediately below the first on-voltage (V _on ), the off time (t _off ) takes almost the same value as the value at the start of pulse charging, and the duty ratio Charging close to pulse charging with (Q) fixed can be realized, and the average charging current is almost constant. When the charging current is cut off, the voltage between terminals of the secondary battery 2 decreases due to a charging overvoltage (η = γ _in · I ^PC , γ _in ; internal resistance of the secondary battery 2, I ^PC ; pulse charging current). However, if charging proceeds immediately to a state where the voltage does not fall below the first on-voltage (V _on ), the off-time (t _off ) increases sharply compared to the value at the start of pulse charging, and the average charging current sharply increases. It becomes smaller and charging ends.

Next, the on-time (t _on ) is measured by using the capacitor 10 and the resistor 1
1, the setting is made using the comparator 12, the resistor 13, and the like. That is, when the voltage between the terminals of the secondary battery 2 is lower than the first on-voltage (V _off ), the comparator 8 is on and charges the capacitor 10. At the same time, the discharge through the resistor 11 occurs.However, the discharge current through the resistor 11 of the capacitor 10 is set sufficiently smaller than the charge current of the capacitor 10, and the capacity of the capacitor 10 and the comparator are set according to the reference voltage. 12 hysteresis resistors
Set at 13 and adjust to desired on-time (t _on ).

Next, the case where the secondary battery described in JP-A-62-90863 is used as the secondary battery 2 will be specifically described.
Hereinafter, a case where two secondary batteries 2 are combined in series will be described in detail.

The standard operating voltage range of the secondary battery 2 is
2.75 V to 4.2 V, and 5.5 V to 8.4 V when two batteries 2 are combined in series. In the present embodiment, a rechargeable battery device having a capacity of 2.0 Ah was manufactured as a power supply for a video movie. The prototype rechargeable battery device is 90mm x 46mm x
It has a size of 26mm and has an internal resistance of 0.15Ω ~ 0.30Ω. The internal resistance of the unit cell of the secondary battery 2 is 0.02Ω to
0.08Ω, and the self-discharge current at 25 ° C. is about 200 μA. By the way, the standard charging condition of the secondary battery 2 is 4.2 V constant voltage charging in which the current is limited to 2 A or less in the case of one cell.
Therefore, the standard charging condition when two secondary batteries 2 are combined in series is 8.4 V constant voltage charging in which the current is limited to 2 A or less. That is, a comparison was made between a battery pack in which two rechargeable batteries 2 were connected in series and a rechargeable battery device according to the present embodiment having the same battery pack when a constant current discharge of 2.0 A was performed. In this case, in a battery pack in which two rechargeable batteries 2 are connected in series, abnormal heat generation starts when the voltage between the terminals exceeds 9.6 V, and finally the battery explodes. However, the first on-voltage (V _on ) is 8.445 V and the first off-voltage (V _off ) is
In the rechargeable battery device 1 according to the present embodiment in which the on-time (t _on ) is set to about 100 msec and the off-time (t _off ) immediately after the shift to the pulse charging is set to about 4 msec, the internal rechargeable battery 2 is set to an appropriate Charging was completed in about 1.5 hours. In addition, when the charging current was limited to 2 A or less and the constant voltage charging of 8.4 V was performed, the charging time required for the battery pack connected in series to the two secondary batteries 2 was 3 hours, The rechargeable battery device according to the present embodiment also has a remarkable effect of shortening the charging time. The effect of shortening the charging time is particularly remarkable when the charging current increases, and there is no particular problem even if the charging current is increased up to about 5A. However, it is not preferable from the viewpoint of safety that the charging current is increased without limit, and it is better to insert a current breaker or the like into the charging / discharging circuit in order to limit the current to about 4 A or less.

By the way, as a switch means, an internal parasitic diode
When the MOS FET 51 having 51A is used, even when the charging of the secondary battery 2 is completely terminated and the MOS FET 51 is in a cut-off state, the voltage across the secondary battery 2 is reduced by the discharge through the parasitic diode 51A. When the voltage becomes equal to or lower than the ON voltage (V _on ) of 1 or the second ON voltage (V ^PC _on ) for pulse charging,
The output voltage of the charge control means changes from the off state to the on state, the MOS FET 51 changes from the cut-off state to the conductive state, and normal (low-loss) discharge is performed. For example, if MOS FETs such as 2SK1286 (NEC), 2SK1136 (Mitsubishi), 2SK1137 (Mitsubishi), and 2SK1114 (Toshiba) are used as the switch means,
FET drain-source on-resistance (R _{DS (on)} ) is 0.04
Ω to 0.12Ω. Of course, if a higher rated MOS FET is used, the drain-source ON resistance (R _{DS (on)} ) of the MOS FET can be further reduced.

By the way, the voltage detection unit 3 and the charge control unit 4 are CMOS
If configured with an IC, etc., these average
It is easy to keep it below A.

With such a configuration, any charger having a maximum output voltage of about 9 V can be properly charged, and in the operating voltage range (5.5 V to 8.4 V), Discharge can be performed in exactly the same manner as when two secondary batteries 2 are connected in series.
The power loss at T is 3 times the power capacity of the rechargeable battery device.
% Or less.

〔The invention's effect〕

As described in detail above, according to the present invention, normal charging can be performed without using a dedicated charger, and a secondary battery can be prevented from being overcharged to a dangerous state, and is safe and normal. And a rechargeable battery device that can be used in exactly the same manner as the secondary battery.

[Brief description of the drawings]

FIG. 1 is a diagram showing a charging mode according to the present invention, and FIG. 2 is a diagram showing an example of a circuit according to an embodiment of the present invention. 2 secondary battery, 3 voltage detector, 4 charge controller, 5
Switch means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H02J 7/00-7/12 H02J 7/34-7/36 H01M 10/44

Claims (1)

(57) [Claims] 1. A non-aqueous rechargeable battery device using a material capable of intercalating cations into gaps of a molecular structure for one of a positive electrode and a negative electrode, or for both a positive electrode and a negative electrode, A secondary battery that can be charged by a charging device, a switching unit having a parasitic diode therein and inserted in series in a discharge / charge circuit of the secondary battery, and a voltage detection unit that detects a terminal voltage of the secondary battery And when the voltage between the terminals of the secondary battery at the time of starting charging by the external charging device is lower than the first off-voltage, based on the detection result of the voltage detecting means, turning on the switch means. The secondary battery is charged based on the control of the external charging device, and after the inter-terminal voltage of the secondary battery reaches the first off-voltage, the switch is repeatedly turned on / off. The secondary battery is pulse-charged by intermittently charging current from the external charging device, and a voltage between terminals of the secondary battery when the pulse charging is off is higher than the first off-voltage. Charge control means for terminating the pulse charging when the off-state voltage is exceeded.