JP2002056900A - Nonaqueous electrolyte type battery device and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an excessive internal pressure rise of a secondary battery main body. SOLUTION: The secondary battery main body 20 is stored in internal space between a battery case 10 and a cover 11. A temperature sensor 27 is fixed to an outer surface of the secondary battery main body 20, when the temperature sensor 27 detects a high temperature >=60 deg.C and a voltage of the secondary battery main body 20 is detected to be >=4.1 V, an FET of a discharge circuit is turned on to suppress battery voltage below a decomposition voltage of electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery device having a non-aqueous electrolyte type secondary battery body.

[0002]

2. Description of the Related Art When charging a secondary battery, control is performed so that the battery voltage does not become excessively high. However, batteries using non-aqueous electrolytes,
For example, in lithium ion batteries, it has been pointed out that the pressure in the secondary battery main body may abnormally increase after charging simply by controlling the charging voltage.

[0003] The cause is that the lithium-ion battery is used in 4.1.
It has been determined that when the battery is left in a high-temperature atmosphere with a charged state of V or more, a decomposition reaction of the electrolyte occurs on the surface of the positive electrode, thereby generating gas. Such a condition may be satisfied when, for example, a mobile phone powered by a lithium ion battery is left in a car in a summer while being charged. In recent years, lithium-ion batteries have been increasingly charged at high voltage, and some secondary batteries use aluminum cases or aluminum laminate films with low withstand voltage. In such a case, there is a risk of rupture or liquid leakage. Therefore, an object of the present invention is to provide a non-aqueous electrolyte battery device that can prevent an excessive increase in internal pressure.

[0004]

Means and Action for Solving the Problems The present inventors have
When the pressure rise of the secondary battery main body using the non-aqueous electrolyte is charged at a predetermined voltage according to the type of the electrolyte and the type of the positive and negative electrodes, for example, at a voltage of 4.1 V or more in a lithium ion battery, It has been found that this is due to the generation of gas due to the decomposition reaction of the electrolyte solution on the positive electrode surface.
The present invention has been made based on such findings. That is, in the battery device according to the first aspect of the present invention, in a battery device including a nonaqueous electrolyte type secondary battery main body, a voltage detecting means for detecting a voltage of the secondary battery main body is provided. When the voltage detecting means detects that the voltage of the secondary battery main body at the time of charging has risen to a first predetermined voltage, the charging is stopped and the secondary battery is set to a second voltage lower than the first predetermined voltage voltage. Discharge to a predetermined voltage. Thus, according to the present invention,
When detecting that the voltage of the non-aqueous electrolyte secondary battery body has risen to the first predetermined voltage by the voltage detecting means during charging, discharging the secondary battery body to a second predetermined voltage lower than the first predetermined voltage. Thereby, the decomposition reaction of the electrolytic solution can be suppressed.

[0005] The inventors have found that when the battery temperature is low even when the battery voltage is higher than a predetermined voltage, for example, in a lithium ion secondary battery, the decomposition reaction of the electrolyte does not occur below 60 ° C. A battery device according to a second aspect of the present invention is a battery device including a non-aqueous electrolyte type secondary battery main body, wherein a voltage detecting means for detecting a voltage of the secondary battery main body; Temperature detecting means for detecting a temperature, when the voltage detecting means detects that the voltage of the secondary battery body during charging has risen to a first predetermined voltage, and wherein the temperature detecting means When it is detected that the temperature of the secondary battery body has risen to a predetermined temperature or more, charging is stopped and the secondary battery body is discharged to a second predetermined voltage equal to or lower than the first predetermined voltage. Characterized in that to.

In a lithium ion secondary battery, when the voltage of the secondary battery body rises to 4.1 V or more and when the temperature of the secondary battery body rises to 60 ° C. or more, the electrolyte solution is Since the decomposition reaction occurs, the battery device according to the invention of claim 3 is a battery device including a lithium ion secondary battery main body, wherein the voltage detection means for detecting a voltage of the secondary battery main body; 3. a temperature detecting means for detecting a temperature of the secondary battery main body, wherein the voltage of the secondary battery main body at the time of charging is set by the voltage detecting means.
When it is detected that the temperature of the secondary battery has risen to 1 V or more, and when the temperature detecting means detects that the temperature of the secondary battery body has risen to 60 ° C. or more, charging is stopped and the secondary battery is charged. It is characterized in that the main body is discharged to less than 4.1V.

According to a fourth aspect of the present invention, there is provided a battery pack in which a lithium ion secondary battery main body is accommodated in a battery case, wherein voltage detecting means for detecting a voltage of the secondary battery main body, Temperature detecting means for detecting the temperature of the battery body, and a discharging circuit for discharging the secondary battery body are provided, and the voltage detecting means determines that the voltage of the secondary battery body during charging has risen to 4.1 V or more. When it is detected, and when the temperature detecting means detects that the temperature of the secondary battery body has risen to 60 ° C. or higher, charging is stopped and the secondary battery body is discharged by the discharging circuit. It is characterized by discharging to less than 4.1V.

[0008]

According to the present invention, when the voltage detecting means detects that the voltage of the nonaqueous electrolyte secondary battery body has risen to the first predetermined voltage during charging, the secondary battery body is released. By discharging to a lower voltage, gas generation due to the decomposition reaction of the electrolytic solution is prevented beforehand, and an increase in the internal pressure of the secondary battery body is prevented. In addition, even if the battery voltage is high, if the battery temperature is low, no gas is generated.Therefore, both the battery voltage and the battery temperature are detected, and when both exceed the predetermined voltage and the predetermined temperature, discharge is performed. If only one of them is exceeded, excessive discharge can be prevented by employing a configuration in which discharge is not performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to a battery pack for a portable telephone will be described with reference to the drawings. FIG. 1 is an exploded view of the overall structure of the battery pack according to the present embodiment. This is because a secondary battery main body 20 is placed inside a battery case 10 made of, for example, a synthetic resin having a flat box shape.
And housed in a structure sealed with a lid 11 and detachably attached to a mobile phone (not shown). An end of one surface of the battery case 10 is connected to the secondary battery main body 2 through a window 12 for an external electrode.
The external electrode 26 provided on the battery case 10
Is connected to an internal circuit of the mobile phone when it is mounted on a mobile phone (not shown), so that the secondary battery body 20 can be charged and discharged.

The secondary battery body 20 is manufactured by housing a power generation element 21 wound in a flat spiral shape in a bag 22 made of a plastic film and sealing the opening thereof. Although not shown in detail, the power generating element 21 is configured by winding a positive / negative electrode plate with a separator interposed therebetween, and for example, the positive electrode active material is made of lithium cobalt oxide and the negative electrode active material is made of graphite. A well-known non-aqueous electrolyte type secondary battery using a mixture of ethylene carbonate, diethyl carbonate, and dimethyl carbonate in a ratio of 3: 7 to which lithium hexafluorophosphate is added as an impregnated electrolyte is used. A certain lithium ion secondary battery is constructed. Further, a plastic film having excellent pressure resistance and airtightness obtained by laminating an aluminum foil is used.

A pair of positive and negative lead wires (not shown) are led out from the end of the secondary battery body 20 and connected to a control circuit board 25 provided at the end of the secondary battery body 20.
It is connected to an external electrode 26 via a safety circuit or the like provided on the control circuit board 25.

A temperature sensor 27 corresponding to temperature detecting means is fixed on the outer surface of the secondary battery body 20. The temperature sensor 27 is connected to the
Is stored in the battery case 10 and the battery case 10
Is sandwiched between the inner surface of the secondary battery and the outer surface of the secondary battery body 20 to detect the temperature of the secondary battery body 20.

The electrical configuration mounted on the control circuit board 25 is as shown in FIG. The control FET 2 in which the positive electrode lead of the secondary battery body 20 is connected to one of the external electrodes 26 and the negative electrode lead wire is normally on.
8 is connected to the other external electrode 26. A discharge resistor 29 and a discharge FET 30 are provided between the lead wires.
Are provided in order, and the discharging FE is provided.
T30 is normally in an off state, but when it is turned on, the secondary battery body 20 can be discharged. A discharge control IC 32 that supplies a voltage between the lead wires is provided, and a voltage is applied to the temperature sensor 27 from the discharge control IC 32. The discharge control IC 32 monitors the temperature of the secondary battery body 20 and also monitors the voltage of the secondary battery. The discharge control IC 32 is always connected to the discharge FET 3
0 is off and the control FET 28 is on,
When the temperature sensor 27 detects 60 ° C. or higher and the voltage of the secondary battery body 20 reaches the first predetermined voltage of 4.1 V, the FETs 28 and 30 are inverted, and the lead wire of the secondary battery body 20 is turned on. When the voltage between them drops to a certain value (second predetermined voltage) of, for example, 4.1 V or less, each FET 2
The configuration is such that 8, 30 is reversed again to return to the initial state.

Here, the voltage and gas generation of the secondary battery will be described with reference to FIG. After charging the battery pack at a predetermined constant voltage (2.8 V to 4.5 V) for 1 hour at 1 C, the battery pack is heated to a predetermined temperature (60 ° C., 70 ° C., 80 ° C.).
FIG. 4 shows the measurement results of the amount of generated gas when left at 72 ° C.) for 72 hours. The battery pack used for the test has a discharge capacity of 550 mAh. From FIG. 4, 70 ° C. and 80 ° C.
When the battery pack is left unattended, the voltage is 4.1
It is understood that when the voltage exceeds V, the electrolytic solution is oxidatively decomposed by the catalytic action of the positive electrode. Therefore, when the battery voltage is 4.1 V or more and the battery temperature is 60 ° C. or more, the generation of gas is prevented by lowering the battery voltage by discharging, and the internal pressure of the battery body is increased. Can be prevented.

The operation of this embodiment is as follows. When the mobile phone is set in the charger, control FET2
8 is on, the discharging FET 30 is off, and the secondary battery body 20 is in a state of being connected to the charger. When the secondary battery body 20 is fully charged, its voltage reaches about 4.2 V, but there is no particular problem since the temperature of the atmosphere is usually 60 ° C. or less. Here, if the mobile phone is exposed to a high-temperature atmosphere such as being left in a car in summer, for example,
The temperature of the secondary battery body 20 also becomes abnormally high, and as a result, the electrolytic solution may cause a decomposition reaction on the surface of the positive electrode in the secondary battery body 20, thereby generating gas.

Accordingly, when the temperature sensor 27 detects high temperature of 60 ° C. or more in the secondary battery body 20 and detects that the voltage of the secondary battery body 20 is 4.1 V or more, discharge control is performed. The IC 32 turns off the control FET 28 and turns on the discharge FET 30. As a result, the secondary battery main body 20 is disconnected from the charger, and the discharge is performed by the discharge circuit 31, so that the battery voltage gradually decreases. When the battery voltage falls below the decomposition voltage of the electrolytic solution, the discharge control IC 32
Is turned off, and the control FET 28 is turned on. As a result, generation of gas is prevented, and an increase in the internal pressure is suppressed, so that the battery pack can be prevented from abnormally expanding or severely ruptured.

As described above, in this embodiment, when the voltage and temperature of the secondary battery body are detected to rise above predetermined values, the battery voltage is discharged to below the decomposition voltage of the electrolytic solution. This has the effect of reliably preventing expansion or rupture.

The present invention is not limited to the embodiments described above with reference to the drawings. For example, the following embodiments are also included in the technical scope of the present invention. Various changes can be made without departing from the scope of the present invention.

In the above-described embodiment, the secondary battery main body 20 is housed in the battery case 10 together with a protection circuit and the like to constitute a battery pack, and the secondary battery body 20 is detachably attached to the portable telephone. It is not limited. For example, the present invention can also be applied to a battery device having a built-in structure in which a secondary battery main body is directly built in a device.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a battery pack showing one embodiment of the present invention.

FIG. 2 is a sectional view thereof.

FIG. 3 is a block diagram showing an electric circuit in the battery pack.

FIG. 4 is a diagram showing a correlation between a voltage of a battery pack and an amount of generated gas.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Battery case 20 ... Secondary battery main body 25 ... Control circuit board 27 ... Temperature sensor (temperature detection means) 28 ... Control FET 29 ... Discharge resistance 30 ... Discharge FET 31 ... Discharge circuit 32 ... Discharge control IC

Claims (4)

[Claims] 1. A battery device comprising a non-aqueous electrolyte type secondary battery main body, comprising: a voltage detecting means for detecting a voltage of the secondary battery main body; When detecting that the voltage of the secondary battery main body has risen to the first predetermined voltage, stopping charging and discharging the secondary battery main body to a second predetermined voltage equal to or lower than the first predetermined voltage. Characteristic non-aqueous electrolyte type battery device. 2. A battery device comprising a non-aqueous electrolyte type secondary battery main body, a voltage detecting means for detecting a voltage of the secondary battery main body, and detecting a temperature of the secondary battery main body. Temperature detecting means, when the voltage detecting means detects that the voltage of the secondary battery body at the time of charging has risen to a first predetermined voltage, and When detecting that the temperature of the battery main body has risen to a predetermined temperature or higher, charging is stopped and the secondary battery main body is discharged to a second predetermined voltage lower than the first predetermined voltage. Water electrolyte type battery device. 3. A battery device comprising a lithium ion secondary battery body, a voltage detecting means for detecting a voltage of the secondary battery body, and a temperature detecting means for detecting a temperature of the secondary battery body. Is provided when the voltage detecting means detects that the voltage of the secondary battery main body at the time of charging has risen to 4.1 V or more, and the temperature of the secondary battery main body is detected by the temperature detecting means. A lithium ion secondary battery device characterized in that when it is detected that the temperature has risen to 60 ° C. or higher, charging is stopped and the secondary battery body is discharged to less than 4.1 V. 4. A battery comprising a lithium ion secondary battery main body housed in a battery case, a voltage detecting means for detecting a voltage of the secondary battery main body, and a temperature detecting means for detecting a temperature of the secondary battery main body. Means, and a discharge circuit for discharging the secondary battery main body is provided, and when the voltage detecting means detects that the voltage of the secondary battery main body at the time of charging has risen to 4.1 V or more, and When the temperature detecting means detects that the temperature of the secondary battery main body has risen to 60 ° C. or higher, it stops charging and discharges the secondary battery main body to less than 4.1 V by the discharging circuit. Characteristic battery pack.