JPH07107677A - Cleaner for secondary battery - Google Patents

Abstract

PURPOSE:To charge a secondary battery completely by raising its charging rate, and to reduce the cost by a simple circuit structure. CONSTITUTION:In a secondary battery charger 1 for charging a nonaqueous secondary battery by the use of a carbonaceous material which can be doped with lithium ions or dedoped as a negative electrode active substance, an output voltage correcting circuit 2 is provided. It has a charge current vs. output voltage characteristic which raises (or lowers) output voltage Vo corresponding to the increase (or decrease) of charge current Io, so that especially, impressed voltage Vb to the body Bo of a secondary battery excluding the resistance component Rm connected in series is approximately constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery charging device for charging a non-aqueous secondary battery using a carbonaceous material capable of doping or dedoping lithium ions as a negative electrode active material.

[0002]

2. Description of the Related Art Conventionally, when charging a non-aqueous secondary battery using a carbonaceous material that can be doped or dedoped with lithium ions as a negative electrode active material, a charging current I to be output is output.
The magnitude of o or the magnitude of the output voltage Vo is controlled to be constant, and the charging is terminated when the magnitude of the charging current Io in the area where the output voltage Vo is constant decreases to a preset value. The secondary battery charging device is known from, for example, Japanese Patent Laid-Open No. 5-111184. The charging current Io vs. output voltage Vo characteristic in this case is shown in FIG.

By the way, since this type of non-aqueous secondary battery is vulnerable to overvoltage, a protection circuit is usually incorporated in the battery case of the secondary battery to protect the battery. However, in this case, the protection circuit is connected in series to the secondary battery body, and even if the output voltage Vo of the charging device is set to the required charging voltage, a voltage drop occurs due to the resistance of the protection circuit. However, as shown in FIG. 5, the actual applied voltage Vb applied to the secondary battery main body becomes lower than the output voltage Vo. In addition,
The magnitude of the voltage drop depends on the magnitude of the charging current Io. Since the charging current Io increases from the initial charging period to the middle charging period, the voltage drop increases and the charging current Io decreases in the latter charging period. The descent will be small.

As described above, in this type of non-aqueous secondary battery, the applied voltage Vb to the secondary battery main body during charging is
Is lower than the charging voltage required by the
In the latter half of charging, the applied voltage Vb to the secondary battery main body gradually increases as the charging current Io decreases. Therefore, even if the protection circuit of the secondary battery is not activated, the safety factor must be taken into consideration and the charging must be terminated at a somewhat low applied voltage Vb, which causes a problem that the charging factor is lowered.

The present invention has solved the problems existing in the prior art as described above. It is possible to achieve full charge by increasing the charging rate of the secondary battery and to realize it at low cost with a simple circuit configuration. The purpose is to provide a charging device for a secondary battery.

[0006]

The present invention comprises a secondary battery charging device 1 for charging a non-aqueous secondary battery using a carbonaceous material capable of doping or dedoping lithium ions as a negative electrode active material. In doing so, in particular, the output voltage Vo is increased corresponding to the increase (or decrease) of the charging current Io so that the applied voltage Vb to the secondary battery body Bo excluding the resistance component Rm connected in series becomes substantially constant. An output voltage correction circuit 2 having a charging current vs. output voltage characteristic to (or lower) is provided.

In this case, the output voltage correction circuit 2 includes the ground line side output section 4n and the ground line 5n of the charging circuit body 3.
The current detection resistor 6 connected between them, the voltage detection resistor unit 7 connected between the hot line side output unit 4p and the ground line 5n of the charging circuit body 3, and the first detection voltage V1 detected from the voltage detection resistor unit 7. By applying the second detection voltage V2, which changes corresponding to the terminal voltage of the current detection resistor 6, to the input section of the comparator 9, the output section of the comparator 9 has a difference between the first detection voltage V1 and the second detection voltage V2. A control voltage generation unit 8 that obtains a control voltage Vc based on the control voltage Vc and an output control unit 10 that controls the current flowing through the hot line 5p based on the control voltage Vc can be provided. The voltage detection resistor unit 7 is composed of a pair of voltage dividing resistors 7a and 7b connected in series, and the first detection voltage V is supplied from the connecting portion 7c between the voltage dividing resistors 7a and 7b.
1 can be detected.

[0008]

According to the secondary battery charging device 1 of the present invention,
Since the output voltage correction circuit 2 is provided, the output voltage correction circuit 2
Due to the charging current Io vs. output voltage Vo characteristic based on, the output voltage Vo becomes higher (or lower) corresponding to the increase (or decrease) of the charging current Io. Therefore, if a secondary battery is connected to the charging device 1 and charging is performed, the charging current Io becomes large in the initial to middle stages of charging, and the voltage drop due to the resistance Rm connected in series to the secondary battery main body Bo is large. Because,
Since the output voltage Vo is increased by the output voltage correction circuit 2 and the charging current Io is decreased in the latter half of charging and the voltage drop due to the resistance component Rm is decreased, the output voltage Vo is decreased by the output voltage correction circuit 2. The voltage drop is corrected. As a result, the applied voltage Vb to the secondary battery body Bo is maintained substantially constant even if the charging current Io increases or decreases.

In this case, according to the specific configuration of the output voltage correction circuit 2, first, the output voltage is output from the voltage detection resistor portion 7, that is, the connection portion 7c between the pair of voltage dividing resistors 7a and 7b connected in series. The first detection voltage V1 corresponding to
It is applied to the non-inverting input section of the comparator 9 in the control voltage generation section 8. Further, the charging current I is applied to the current detection resistor 6.
A terminal voltage Vs corresponding to o is generated, and this terminal voltage Vs
The second detection voltage V2 that changes corresponding to
Is added to the inverting input section of. As a result, a control voltage Vc based on the deviation between the first detection voltage V1 and the second detection voltage V2 is obtained at the output part of the comparator 9, and this control voltage Vc is given to the output control part 10. Then, the current flowing through the hot line 5p is controlled based on the control voltage Vc. Therefore, when the charging current Io increases and the terminal voltage Vs rises, the second detection voltage V2 rises accordingly, so that the output voltage Vo rises due to the function of the output control unit 10 based on the control voltage Vc. Controlled.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings.

First, a secondary battery B which can be charged by the charging device 1 according to the present invention will be described with reference to FIG.

The secondary battery B is a non-aqueous system, and in principle has a positive electrode active material Y and a negative electrode active material X via a separator S, and the current collector Yp in the positive electrode active material Y is a positive (+) electrode. The current collector Xp in the negative electrode active material X becomes a negative (−) electrode.

The positive electrode active material Y is a lithium ion (L
i ⁺ ), as long as it is a substance capable of dedoping or doping,
Lithium cobalt oxide, such as Li _X Co _Y M _Z O
₂ (where M is at least one metal selected from Al, In and Sn, and X, Y and Z are each 0 <X ≦
1.1, 0.5 <Y ≦ 1, Z ≦ 0.1, respectively. ), Li _X CoO ₂ (0 <X ≦ 1), Li _X Co _Y Ni
_Z O ₂ (0 <X ≦ 1, Y + Z = 1), lithium nickel oxide such as Li _X NiO ₂ (0 <X ≦ 1), lithium manganese oxide such as Li _X MnO ₂ , Li _X Mn ₂ O
₄ (0 <X ≦ 1), LiCo _X Mn _2-X O ₄ (0 <X ≦ 0.
5), lithium chrome oxides such as Li _X Cr ₃ O ₈
(0 <X ≦ 1), LiCrO ₂ , lithium vanadium oxide, for example, Li _X V ₂ O ₅ (0 <X ≦ 1), Li _X V ₆
O ₁₃ , Li _{1 + X} V ₃ O ₈ , lithium molybdenum oxide, for example, Li _X MoO ₃ , lithium molybdenum disulfide, for example, Li _X MoS ₂ , lithium titanium oxide, for example,
Li _X Ti ₂ O ₄ , lithium titanium sulfide, for example, Li _X
Ti ₂ S ₂ or the like is used. In addition, especially preferable are lithium cobalt oxide and lithium manganese oxide.

On the other hand, the negative electrode active material X is a carbonaceous material capable of being doped or dedoped with lithium ions (Li ⁺ ), for example, graphite, pyrolytic carbon, pitch coke, needle coke, petroleum coke, organic polymer firing. The body (phenol resin, furan resin, polyacrylonitrile, etc.) is used.

The positive electrode active material Y and the negative electrode active material X are each in the form of particles and are applied to the current collectors Yp and Xp using a metal foil, respectively. Then, it is spirally wound through the separator S, further housed in the battery can K and attached with lead wires, and impregnated with the electrolyte solution L (non-aqueous) and sealed.

The electrolyte in the non-aqueous electrolyte solution L is, for example, LiClO ₄ , LiAsF ₆ , LiPF ₆ ,
LiBF ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃
Any one kind or a mixture of two or more kinds of lithium salts such as SO ₂ ) ₂ NLi is used. The solvent of the electrolyte solution L is, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-
Any one kind or a mixture of two or more kinds of methyltetrahydrofuran, 1,3-dioxolane, sulfolane, methylsulfolane, acetonitrile, propionitrile, methyl formate, ethyl formate, methyl acetate, ethyl acetate and the like is used.

Further, the separator S is made of polyethylene,
One or two or more kinds of laminating films of polyolefin microporous film such as polypropylene, a single film of non-woven fabric of polyolefin, polyester, polyamide, cellulose or the like or a laminating film with the microporous film is used. A polyethylene microporous film is particularly preferable.

Next, the configuration of the charging device 1 according to this embodiment, which is suitable for charging such a non-aqueous secondary battery, will be described with reference to FIG.

In FIG. 1, 1 is a charging device, and B is a secondary battery connected to the charging device 1. Connected to the charging device 1 is an AC input unit 21a, 21b, a charging circuit body 3 that rectifies and smoothes the AC input supplied to the AC input unit 21a, 21b, and outputs DC, and an output side of the charging circuit body 3. The stabilization circuit 22 having the output voltage correction circuit 2 for The stabilizing circuit 22 usually includes a constant current circuit, but it is omitted in this embodiment. Further, 4p is a hot line side output section, 4n is an earth line side output section, and the secondary battery B is connected to the hot line side output section 4p and the earth line side output section 4n. The secondary battery B has a built-in secondary battery body Bo and a protection circuit, and the resistance component Rm of the protection circuit is connected in series to the secondary battery body Bo.

Next, the configuration of the output voltage correction circuit 2 provided in the charging device 1 according to this embodiment will be specifically described. In the output voltage correction circuit 2, 10 is an output control unit, which includes control transistors 23 and 24. The collector of the control transistor 23 is connected to the hot line 5p on the charging circuit body 3 side, and the emitter is connected to the hot line side output section 4p. In addition, the control transistor 24
Is connected to the base of the control transistor 23, and the emitter of the control transistor 24 is connected to the ground line 5n. Ra is the control transistor 2
3 shows a bias resistor connected between the emitter and the base of FIG.

The earth line side output unit 4n is connected to the earth line 5n on the charging circuit body 3 side via the current detection resistor 6.
Connect to. On the other hand, the voltage detection resistor unit 7 is provided between the hot line side output unit 4p and the ground line 5n on the charging circuit body 3 side.
Connect. The voltage detection resistor unit 7 is composed of a pair of voltage dividing resistors 7a and 7b connected in series. On the other hand, 8 is a control voltage generation unit, which includes a comparator 9. The non-inverting input part of the comparator 9 is a connecting part 7 between the voltage dividing resistors 7a and 7b.
A constant voltage diode 25 is connected between the inverting input part of the comparator 9 and the ground line side output part 4n
Connect. The output of the comparator 9 is connected to the base of the control transistor 24.

The charging current I depends on the size of the resistance value Rs of the current detection resistor 6 and the sizes of the voltage dividing resistors 7a and 7b.
Even if o increases or decreases, the applied voltage Vb to the secondary battery main body Bo excluding the resistance component Rm connected in series can be set to be substantially constant.

Next, the operation of the charging device 1 according to this embodiment will be described with reference to FIGS. 1, 3 and 4.

Charging current Io vs. output voltage V of the charging device 1
The o and applied voltage Vb characteristics are as shown in FIG. That is, as is apparent from the figure, when the charging current Io increases, the output voltage Vo of the charging device 1 also increases correspondingly, but the applied voltage Vb applied to the secondary battery body Bo is substantially constant. Maintained at. Therefore, when the charging current Io is zero, the original applied voltage Vb required for the secondary battery main body Bo is required.
By setting, the regular voltage can be always applied to the secondary battery body Bo.

Therefore, during the charging from the initial charging period to the middle charging period, as shown in FIG. 3, the constant current charging region is the charging current Is. In this region, the output voltage Vo and the applied voltage Vb gradually increase with the progress of charging, and finally, as shown in FIG. 4, the output voltage Vo reaches the maximum voltage Vom and the applied voltage Vb also reaches the maximum voltage. Reach Vbm. The maximum voltage Vbm is the maximum allowable voltage applied to the secondary battery body Bo. On the other hand, when the maximum voltage Vbm is reached, the voltage shifts to the constant voltage control region, and accordingly, the charging current Io gradually decreases as shown in FIG. Further, the voltage drop due to the resistance component Rm also decreases, but at the same time, the output voltage Vo also decreases as shown in FIG. 4, and the applied voltage Vb is held at the maximum voltage Vbm. Then, if the charging current Io has decreased to a preset value, charging is terminated. In FIG. 3, the phantom line shows the case where the conventional device (characteristic of FIG. 5) is used, but the applied voltage by the conventional device becomes lower than the applied voltage Vbm according to the present invention as indicated by Vbr, and Along with this, the charging current also has an earlier decreasing point as indicated by Ior, and the charging rate decreases. However, in the charging device 1 according to the present invention, the charging rate can be dramatically increased, and the experimental value shows that the charging rate after 1 hour is approximately 85% to 95%.
Could be improved to%.

In this case, in the output voltage correction circuit 2, the terminal voltage Vs of the current detection resistor 6 becomes higher (or lower) due to the increase (or decrease) of the charging current Io, and the second detection voltage V2. To increase (or decrease). As a result, a control voltage Vc based on the deviation between the first detection voltage V1 and the second detection voltage V2 is obtained at the output part of the comparator 9, and this control voltage Vc is given to the base of the control transistor 24 in the output control part 10. . As a result, the control transistors 23 and 24 are controlled, and the current flowing through the hot line 5p is controlled so as to increase (or decrease) the output voltage Vo. At this time, the current detection resistor 6
Since the resistance value Rs of the secondary battery is set to the condition that the influence of the resistance component Rm is eliminated, the voltage drop due to the resistance component Rm is canceled, and the secondary battery is not affected by the increase or decrease of the charging current Io. The fluctuation of the applied voltage Vb with respect to the main body Bo can be suppressed.

The embodiment has been described in detail above.
The present invention is not limited to such an embodiment.
For example, although the resistance component Rm is based on the protection circuit of the secondary battery, it is a concept including the resistance component of the connection cord itself. Further, the voltage detection resistor section does not prevent the use of a single resistor. Furthermore, the current detection resistor can also be used for current detection when forming a constant current circuit. In addition, the detailed circuit configuration and method may be arbitrarily changed without departing from the scope of the present invention.

[0028]

As described above, the present invention relates to a secondary battery charging device for charging a non-aqueous secondary battery using a carbonaceous material capable of being doped or dedoped with lithium ions as a negative electrode active material, , So that the applied voltage to the main body of the secondary battery, excluding the resistance connected in series, is approximately constant,
Equipped with an output voltage correction circuit that has a charging current vs. output voltage characteristic that raises (or lowers) the output voltage in response to an increase (or decrease) in the charging current, thus increasing the charging rate of the secondary battery to achieve full charging. And a remarkable effect that it can be realized at a low cost with a simple circuit configuration.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a charging device according to the present invention,

FIG. 2 is a principle configuration diagram of a non-aqueous secondary battery,

FIG. 3 is a charging characteristic diagram of the charging device,

FIG. 4 is a characteristic diagram of load current vs. output voltage (applied voltage) by the same charging device,

FIG. 5 is a characteristic diagram of load current vs. output voltage (applied voltage) by a charging device according to a conventional technique,

[Explanation of symbols]

 1 Charging device 2 Output voltage correction circuit 3 Charging circuit main body 4p Hot line side output part 4n Earth line side output part 5p Hot line 5n Earth line 6 Current detection resistor 7 Voltage detection resistor part 7a Voltage dividing resistor 7b Voltage dividing resistor 7c Connection part 8 Control Voltage Generation Section 9 Comparator 10 Output Control Section B Secondary Battery Bo Secondary Battery Main Body Rm Resistance Vb Applied Voltage Vo Output Voltage Io Charging Current V1 First Detection Voltage V2 Second Detection Voltage Vc Control Voltage

Claims (3)

[Claims] 1. A secondary battery charging device for charging a non-aqueous secondary battery using a carbonaceous material capable of being doped or dedoped with lithium ions as a negative electrode active material, wherein a resistance component connected in series is Exclude (or decrease) the charging current so that the applied voltage to the main body of the secondary battery is almost constant
A charging device for a secondary battery, comprising: an output voltage correction circuit having a charging current-output voltage characteristic that raises (or lowers) the output voltage in accordance with the above. 2. The output voltage correction circuit comprises a current detection resistor connected between the ground line side output section and the ground line of the charging circuit body, and a voltage detection resistor connected between the hot line side output section and the ground line of the charging circuit body. Section, the first detection voltage detected from the voltage detection resistance section and the second detection voltage that changes corresponding to the terminal voltage of the current detection resistance are applied to the input section of the comparator, so that the first detection at the output section of the comparator The secondary circuit according to claim 1, further comprising: a control voltage generation unit that obtains a control voltage based on a deviation between the voltage and the second detection voltage, and an output control unit that controls a current flowing through the hot line based on the control voltage. Battery charger. 3. The secondary battery according to claim 2, wherein the voltage detection resistor section is composed of a pair of voltage dividing resistors connected in series, and the first detection voltage is detected from a connecting portion between the voltage dividing resistors. Charging device.