JP4518591B2 - Battery pack with built-in thin battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin battery using a film outer package, and particularly to a thin battery capable of interrupting current when the internal pressure of the film outer package increases and a pack battery using the thin battery.
[0002]
[Prior art]
A thin battery having a film outer package is shown in the plan view of FIG. 1 and the cross-sectional view of FIG. The thin battery shown in this figure has a power generation element 7 incorporated in a film outer package 5. In the power generation element 7, the electrolyte layer 3 is provided between the positive electrode 1 and the negative electrode 2. In the thin battery shown in these drawings, the outer periphery of the power generation element 7 is used as the sealing portion 4 of the film outer package 5. The film outer package 5 that seals the power generation element 7 is formed by laminating two laminate films 5A on both surfaces of the power generation element 7, laminating the outer periphery of the power generation element 7, and heat-sealing the laminated portion.
[0003]
A thin battery having this structure may be used in an abnormal state such as overcharging, and the internal pressure may increase. When the internal pressure rises, as shown by the chain line in FIG. 2, the film outer package 5 expands, and when the internal pressure further rises, there is a risk of bursting. In order to prevent rupture of the film outer package, as shown in FIG. 3, a thin battery in which a pressure release means 28 is provided on a part of the film outer package 5 is described in Japanese Patent Laid-Open No. 9-199099.
[0004]
In the thin battery shown in this figure, a rupture film provided with a breaking groove is used as the pressure release means 28. The pressure release means 28 is, for example, an internal pressure of the film outer package 5 of 1.2 to 20 kgf / cm. ² When it rises, the film exterior body 5 is broken and opened. Furthermore, the above publication also describes that the welded portion of the film outer package is opened as a pressure release means so as to open at a predetermined pressure.
[0005]
[Problems to be solved by the invention]
However, as shown in FIG. 3, a thin battery that has a structure in which a rupture groove is provided in the film outer package, or is welded so as to peel off the welded portion of the film outer package and the film outer package opens when the internal pressure increases. It is difficult to set the opening pressure accurately. Furthermore, a thin battery having a rupture groove formed in a part of the film outer package may be broken and cannot be used when subjected to an impact. If the breaking groove is made shallow to make this portion strong so that this problem does not occur, it will not be able to break when the internal pressure rises, and it will not be possible to prevent the internal pressure from rising.
[0006]
Furthermore, the thin battery shown in FIG. 3 cannot have a reusable structure when the internal pressure rises and the pressure release means is opened, even if the internal pressure subsequently decreases to a normal state.
[0007]
The present invention has been developed for the purpose of solving such drawbacks, and an important object of the present invention is to effectively prevent an increase in the internal pressure of the film outer package and to accurately determine that the internal pressure has increased. It is an object of the present invention to provide a thin battery capable of detecting the internal pressure and preventing an increase in internal pressure and a battery pack incorporating the thin battery.
[0008]
[Means for Solving the Problems]
The present invention In In order to achieve the above-described object, the thin battery has the following configuration. The thin battery includes a power generation element 7 including a positive electrode 1 and a negative electrode 2, and a film outer package 5 formed by housing the power generation element 7 in an internal sealed chamber. Further, the thin battery has a strain sensor 8 attached to the surface of the film outer package 5.
[0009]
Furthermore, the present invention In The thin battery is a lithium ion secondary battery.
[0010]
Furthermore, the present invention In In the thin battery, the film outer package 5 is a laminate film 5A. The laminate film 5A is formed by laminating and bonding aluminum between thermoplastic films. The laminate film 5 </ b> A is thermally welded at the sealing portion 4.
[0011]
Furthermore, the present invention Thin The battery pack with a built-in type battery cuts off the current when the internal pressure of the thin battery rises and the thin battery in which the power generation element 7 including the positive electrode 1 and the negative electrode 2 is housed in the film outer package 5. And a protection circuit 21. The protection circuit 21 includes a strain sensor 8 attached to the surface of the film exterior body 5, and a cutoff switch 16 that cuts off a current flowing through the battery 18 by an output signal of the strain sensor 8. Further, the protection circuit 21 detects the deformation due to the increase in the internal pressure of the film exterior body 5 by the strain sensor 8, and when the strain sensor 8 detects the deformation of the film exterior body 5, the cutoff switch 16 is turned off to interrupt the battery current. It is configured as follows.
[0012]
Furthermore, the present invention Thin The battery pack with a built-in battery includes a strain sensor 8 having a protective circuit 21 attached to the surface of the film outer package 5, an energizing switch 23 that is switched by an output signal of the strain sensor 8, and the energizing switch 23. The heating resistor 24 whose energized state is controlled by the heating resistor 24 and the fuse 22 which is disposed at a position heated by the heating resistor 24 and connected in series with the battery 18 are provided. The protection circuit 21 detects deformation due to an increase in internal pressure of the film outer package 5 by the strain sensor 8. When the strain sensor 8 detects deformation of the film outer package 5, the energization switch 23 is turned on to supply a heating current to the heating resistor 24. The heating resistor 24 heated by the heating current blows the fuse 22 to cut off the battery current.
[0013]
Furthermore, the present invention Thin In the battery pack incorporating the battery, the protection circuit 21 is connected to a constant current circuit 25 that controls the current flowing through the heating resistor 24 with the energization switch 23 turned on.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the examples shown below exemplify a thin battery for embodying the technical idea of the present invention and a battery pack incorporating the thin battery, and the present invention includes the thin battery and the battery pack as follows. Not specified.
[0015]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0016]
The thin battery shown in the plan view of FIG. 4 and the cross-sectional view of FIG. 5 has a strain sensor 8 attached to the surface of the film outer package 5. The strain sensor 8 is bonded and fixed to the film outer package 5. The strain sensor 8 detects deformation of the film outer package 5. The thin battery shown in the figure extends in the vertical direction and fixes the strain sensor 8. The strain sensor 8 fixed in this direction can detect the deformation of the film outer package 5 with high sensitivity. This is because the film outer package 5 extends in the vertical direction and is easily deformed. However, the strain sensor can be fixed to the film exterior body in the horizontal direction or in a posture inclined with respect to the vertical and horizontal directions.
[0017]
As the strain sensor 8, all sensors that can detect the deformation of the film outer package 5 can be used. As the strain sensor 8, a sensor that detects the elongation of the film outer package 5 and / or the change in shape thereof can be used. In the thin battery, when the internal pressure rises and the film outer package 5 swells as shown by a chain line in FIG. 5, the film outer package 5 expands and the shape changes. Therefore, the strain sensor 8 can detect the increase in the internal pressure by detecting the elongation of the film outer package 5. However, it goes without saying that a strain sensor that detects a change in the shape of the film outer package can also be used.
[0018]
A strain sensor 8 attached to the film outer package 5 is shown in FIG. The strain sensor 8 in this figure is a strain gauge in which a metal foil wire 9 is fixed to a flexible insulating sheet 9. The strain gauge of this figure has a metal foil wire 9 extending vertically and arranged in parallel, and the whole is connected in series. The strain gauge having this structure detects deformation by a change in the resistance value of the metal foil. The metal foil has a property that the resistance increases when it is stretched and decreases when it is compressed. For the metal foil, for example, a copper / nickel alloy or a nichrome alloy is used.
[0019]
The strain gauge having this structure detects the elongation in the vertical direction with high sensitivity. Therefore, the strain gauge is fixed to the film exterior body 5 so that the wire 9 faces the longitudinal direction of the film exterior body 5, and the deformation of the film exterior body 5 can be detected with high sensitivity by the strain gauge.
[0020]
The strain gauge is extended together with the film outer package 5 to detect deformation of the film outer package 5. Therefore, the strain sensor 8 is attached so as to extend integrally with the film outer package 5. The strain sensor 8 is preferably bonded to the film outer package 5 via an adhesive. As the adhesive, for example, a cyanoacrylate-based instantaneous adhesive, an epoxy-based, acrylic-based, silicon-based, urethane-based adhesive, or the like is used. The strain sensor can be bonded to the film outer package via adhesive tape on both sides or by heat welding.
[0021]
The signal from the strain sensor 8 is input to the detection circuit 11 shown in FIG. The detection circuit 11 in this figure includes a Wheatstone bridge circuit 12 and an amplifier 13. The strain sensor 8 is connected as a resistance element of the Wheatstone bridge circuit 12. The Wheatstone bridge circuit 12 is preferably connected to an AC power source 14. Although a DC power supply can be used, a DC amplifier that amplifies the output signal, drift correction, and the like become complicated. The resistance connected to the Wheatstone bridge circuit 12 is adjusted so that the output is 0 in a balanced manner in a state where the film outer package 5 is not deformed. When the film outer package 5 is deformed and the resistance value of the strain gauge changes, the Wheatstone bridge is out of balance and the output voltage increases. Therefore, the detection circuit 11 can detect the amount of deformation of the film outer package 5 based on the magnitude of the output signal of the Wheatstone bridge circuit 12. Since the output voltage of the Wheatstone bridge circuit 12 is small, it is amplified by the amplifier 13 and input to the control circuit 15.
[0022]
As shown in FIG. 4, the detection circuit 11 and the control circuit 15 are built in a case 26 of a battery pack. FIG. 8 shows a circuit diagram of the battery pack. The battery pack in this figure inputs a signal from the detection circuit 11 to the control circuit 15 and controls the cutoff switch 16 by the control circuit 15 to cut off the current when the film outer package 5 is deformed. When the internal pressure of the battery 18 rises and the film outer casing 5 expands and a signal is input from the detection circuit 11, the control circuit 15 turns off the cutoff switch 16 to cut off the current. The internal pressure of the battery 18 rises and the film outer package 5 swells mainly during charging. Therefore, in the battery pack of FIG. 8, the FET is connected in the direction in which the charge current is cut off by the cut-off switch 16.
[0023]
In the battery pack of this figure, a switching element 17 that cuts off a discharge current is connected in series with a cut-off switch 16. The cutoff switch 16 and the switching element 17 are connected between the battery 18 and the output terminal 19 to cut off the charging current or discharging charge. The cutoff switch 16 and the switching element 17 are FETs and are connected in series so that the drain and the source are in opposite directions.
[0024]
The switching element 17 that cuts off the discharge current is switched from on to off when the battery voltage becomes lower than the set voltage, and cuts off the discharge current. Therefore, the control circuit 15 detects the battery voltage and controls the switching element 17. When the internal pressure of the battery 18 increases and a signal is input from the detection circuit 11, the control circuit 15 can switch off both the cutoff switch 16 and the FET that is the switching element 17. When the film outer package 5 is deformed, the battery pack that turns off both FETs can block both the charging current and the discharging current when the internal pressure of the battery 18 increases.
[0025]
The control circuit 15 has a built-in latching circuit for maintaining a state in which the battery internal pressure increases and the cutoff switch 16 is turned off. A reset switch 20 is connected to the latching circuit. The latching circuit is reset when the reset switch 20 is operated, and the state where the cutoff switch 16 is held in the OFF state is reset. When the internal pressure of the battery 18 becomes high, the control circuit 15 that turns off both the cutoff switch 16 and the switching element 17 holds both the cutoff switch 16 and the switching element 17 in the off state by a latching circuit. Even after the battery internal pressure rises and the shut-off switch 16 is turned off, the battery pack having this structure can be reused when the battery internal pressure decreases to a normal state. This is because the reset switch 20 can be operated to reset the latching circuit and return the cutoff switch 16 and the switching element 17 to the ON state.
[0026]
In the battery pack of this figure, the cutoff switch 16 can be used in combination with a switching element that prevents overcharge. In other words, a switching element for preventing overcharge can be used in combination with the cutoff switch. The battery pack that prevents overcharging by the cut-off switch 16 detects the overcharge of the battery by the control circuit 15, and switches off the cut-off switch 16 when the battery 18 is overcharged. In the battery pack having this structure, when the battery 18 is overcharged or when the internal pressure of the battery 18 rises, the cutoff switch 16 is switched off. In the battery pack of FIG. 8, a protection circuit 21 is configured by the strain sensor 8, the detection circuit 11, the control circuit 15, and the cutoff switch 16.
[0027]
The pack battery shown in FIG. 9 includes a fuse 22 that cuts off the current when the internal pressure of the battery 18 increases, in addition to the overcharge and overdischarge prevention circuit 27 that prevents overcharge and overdischarge of the battery 18. . The fuse 22 is connected in series with the battery 18 and interrupts the current flowing through the battery 18.
[0028]
The battery pack shown in this figure is thermally blown by the energizing switch 23 that is turned on and off by the output signal of the detection circuit 11, the heating resistor 24 that heats the fuse 22 when the energizing switch 23 is turned on, and the heating resistor 24. A fuse 22. In the battery pack shown in the figure, the energization switch 23 is an FET that is a switching element. Furthermore, the battery pack shown in the figure has a constant current circuit 25 connected in series with the energization switch 23 to control the current flowing through the heating resistor 24.
[0029]
The constant current circuit 25 can prevent a change in the heating current of the heating resistor 24 due to a change in battery voltage when the energization switch 23 is turned on. The heating current controlled by the constant current circuit 25 to flow through the heating resistor 24 is set to a current that can heat the heating resistor 24 and heat the fuse 22. In the illustrated battery pack, two fuses 22 are connected in series between the battery battery output terminal 19 and the battery 18. One fuse 22 is connected to the battery 18, the other fuse 22 is connected to the output terminal 19 of the battery pack, and an intermediate connection point of the fuse 22 is connected to the heating resistor 24.
[0030]
Further, two heating resistors 24 are disposed in proximity to the fuse 22. There are two heating resistors 24, and each heating resistor 24 is disposed close to each fuse 22. The heating resistors 24 are connected in parallel to each other, with one end connected to the intermediate connection point of the fuse 22 and the other end connected to the energizing switch 23.
[0031]
In the battery pack with this structure, when the internal pressure of the battery 18 is normal, the output signal level of the detection circuit 11 is low and the energization switch 23 is turned off. When the energization switch 23 is in the OFF state, no current flows through the heating resistor 24. Therefore, the fuse 22 is not heated by the heating resistor 24, and the fuse 22 is not blown. In this state, the battery pack is charged or discharged.
[0032]
When the internal pressure of the battery 18 increases and the film outer package 5 swells, this is detected by the strain sensor 8 and the output signal of the detection circuit 11 increases to switch the energization switch 23 from OFF to ON. The energizing switch 23 that is turned on causes a heating current to flow through the heating resistor 24. The heating current is controlled by the constant current circuit 25 and is not affected by the battery voltage. The constant current circuit 25 controls the heating current to a set current. The heating resistor 24 is heated by Joule heat generated by a heating current to blow the fuse 22. When the fuse 22 is blown, the battery 18 is disconnected from the output terminal 19 of the battery pack, and the current is cut off. Since the battery pack having this structure blows the fuse 22 when the internal pressure of the battery 18 rises, the current can be reliably interrupted. In the battery pack shown in FIG. 9, a protection circuit 21 is configured by the strain sensor 8, the detection circuit 11, the energization switch 23, the constant current circuit 25, the fuse 22, and the heating resistor 24.
[0033]
Although the present invention does not specify the type of the thin battery, a thin battery having a structure shown in FIG. 5 is used. The thin battery in this figure has a power generation element 7 built in a sealed chamber of the film outer package 5. In this figure, 1 is a positive electrode, 2 is a negative electrode, 3 is an electrolyte layer, 4 is a sealing portion of the film outer package, 5 is a film outer package, and 6 is a current collecting terminal.
[0034]
The thin battery is a lithium polymer secondary battery or a lithium ion secondary battery. As the lithium polymer secondary battery, a solid or room temperature gel is used as an electrolyte. The lithium polymer secondary battery uses the following combinations for the positive electrode and the negative electrode.
Positive electrode: Lithium manganate Negative electrode: Graphite carbon
Positive electrode …… Vanadium oxide Negative electrode …… Lithium alloy
[0035]
Lithium ion secondary battery is LiPF ₆ The electrolyte solution which consists of solutes, such as a solvent, and a solvent is used, and the following are used for a positive electrode and a negative electrode.
Positive electrode: Lithium cobaltate Negative electrode: Graphite carbon
Positive electrode …… Lithium cobaltate Negative electrode …… Coke carbon
Positive electrode: Lithium nickelate Negative electrode: Graphite carbon
Positive electrode: Lithium manganate Negative electrode: Graphite carbon
Positive electrode …… Lithium cobaltate Negative electrode …… Tin amorphous oxide
[0036]
The film outer package 5 containing the power generation element 7 in a sealed structure is hermetically sealed by thermally sealing the laminated film 5A at the sealing portion 4. As shown in the enlarged sectional view of FIG. 5, the laminate film 5A is a film in which a polypropylene film 5b is laminated on both surfaces of an aluminum foil 5a.
[0037]
A laminate film 5A shown in this figure has a three-layer structure of polypropylene film 5b / aluminum foil 5a / polypropylene film 5b, and a polypropylene film 5b, which is the same plastic film, is laminated on both surfaces of the aluminum foil 5a.
[0038]
A thin battery which is a lithium polymer secondary battery or a lithium ion secondary battery is manufactured as follows.
In this thin battery, the thickness of each layer of the laminate film 5A is set such that the first polypropylene film 5b located inside the film outer package 5 is 50 μm, the aluminum foil 5a is 20 μm, and the second polypropylene located outside the film outer package 5. The film 5b is 80 μm. A modified polypropylene film is used to bond the interface between the aluminum foil 5a and the polypropylene film 5b.
[0039]
The thin battery is manufactured by the following process.
(1) As shown in FIGS. 5 and 10, the laminate film 5A is bent on both sides of the power generation element 7 to form a cylinder, and both ends are stacked at positions that become the surface of the power generation element 7 to heat the stack. Weld. In this step, the portion where the laminate film 5A is thermally welded becomes a cylindrical sealing portion 4A that connects the laminate film 5A in a cylindrical shape. The laminated portion of the laminate film 5 </ b> A is heat-welded without inserting the power generation element 7. However, the laminated portion that becomes the cylindrical sealing portion 4 </ b> A can be heat-welded after the power generation element 7 is inserted. The method of thermally welding the laminated portion before putting the power generating element 7 can be thermally welded by sandwiching the front and back of the laminated portion with a mold of a high frequency induction heating device. The method of heat welding with the power generation element 7 inserted is to heat-weld by pressing the laminated part where the laminate film 5A is laminated on the surface of the power generation element 7 while heating the power generation element 7 from the surface with a heated mold. To do. The width of the cylindrical sealing portion 4A is heat-welded so as to be 20 mm.
[0040]
(2) Thereafter, as shown in FIGS. 10 and 11, one end portion of the laminate film 5A thermally welded to the cylinder is folded and thermally welded with a mold of a high-frequency induction heating device. This sealing part 4 becomes the current collecting terminal side sealing part 4B on the side where the current collecting terminal 6 is not sandwiched. The current collecting terminal side sealing portion 4B that does not sandwich the current collecting terminal 6 cuts one end edge of the laminated film 5A connected in a cylindrical shape, and the laminated film on the side where the other tongue piece 5B that is not cut is cut off. The laminate was folded 180 degrees so as to be in close contact with the surface of 5A, and the laminated portion was thermally welded and sealed in a bag shape. The sealing width of the current collecting terminal side sealing part 4B was 20 mm. When the tongue piece 5B folded back 180 degrees is thermally welded, a thin metal mold is placed inside the laminated film 5A connected in a cylindrical shape so that the laminated film 5A located on both surfaces of the power generation element 7 is not thermally welded. insert. The laminated portion is sandwiched between the mold and an external mold that presses the tongue piece 5B, and is heat-welded by being pressed and heated.
[0041]
(3) The power generation element 7 assembled in advance in an argon atmosphere is inserted into a laminating film 5A (hereinafter referred to as a pouch) in which the laminated portion is thermally welded. The outer shape of the power generation element 7 is about 80 × 30 mm. As shown in the cross-sectional view of FIG. 12, the current collecting terminals 6 of the positive electrode 1 and the negative electrode 2 are sandwiched between the laminate films 5A, and the laminate films 5A on both surfaces of the power generation element 7 are heat-welded at the laminated portion. The current collecting terminal 6 is sandwiched between two laminated films 5A and pulled out to the outside. The width of the current collecting terminal side sealing portion 4B that is heat-welded with the current collecting terminal 6 interposed therebetween is 10 mm.
In the thin battery manufactured in the above state, the sealing portion 4 is in the state shown in FIG. 13, and the overall thickness is 1.5 mm.
[0042]
(4) The strain sensor 8 is attached to the surface of the film outer package 5. As shown in FIG. 5, the strain sensor 8 is adhered and fixed to the surface of the film outer package 5 opposite to the cylindrical sealing portion 4 </ b> A.
[0043]
Furthermore, the thin battery shown in FIGS. 14 and 15 is the same as that described above for the power generation element 7. The laminate film 5A has a three-layer structure of polyethylene film 5c / aluminum foil 5a / polyethylene film 5c. The polyethylene film 5c laminated on both surfaces of the aluminum 5a foil is the same material. In the laminate film 5A, the first polyethylene film 5c (inner side) is 30 μm, the aluminum 5a is 9 μm, and the second polyethylene film 5c (outer side) is 80 μm. Modified polyethylene is used for interfacial adhesion.
[0044]
The thin battery shown in FIGS. 14 and 15 is manufactured as follows.
(1) As shown in FIG. 16, after being folded in half, the laminated portions at both ends are folded back to the upper surface of the power generating element 7, and the laminated portion where the three layers of the laminate film 5A are laminated is subjected to high frequency induction. A bag-shaped pouch is formed by heat welding with a mold of a heating device. The width of the cylindrical sealing portion 4A to be heat-welded is 20 mm. When the laminated portion folded back on the upper surface of the power generation element 7 is thermally welded, a thin metal mold is inserted into the portion where the power generation element 7 is inserted so that the laminate films 5A located on both surfaces of the power generation element 7 are not thermally welded. .
[0045]
(2) After that, the power generation element 7 previously assembled in an argon atmosphere is inserted into the pouch connected in a bag shape in the same process as the above (3), and the current collecting terminals 6 of the positive electrode 1 and the negative electrode 2 are connected. Then, the laminate film 5A is sandwiched between the laminate films 5A, and the laminate films 5A on both sides of the power generation element 7 are heat-welded at the laminated portion. The width of the current collecting terminal side sealing portion 4B that is heat-welded by sandwiching the current collecting terminal 6 was 10 mm.
The thin battery manufactured in the above state has an overall thickness of 1.7 mm.
[0046]
(3) The strain sensor 8 is attached to the surface of the film outer package 5. As shown in FIG. 15, the strain sensor 8 is bonded and fixed to the surface of the film outer package 5 opposite to the cylindrical sealing portion 4 </ b> A.
[0047]
Furthermore, as shown in FIGS. 17 and 18, the thin battery can be heat-welded with the laminate film 5 </ b> A on the outer periphery of the power generation element 7. The same thing as the above-mentioned thin battery is used for the electric power generation element 7 and the laminate film 5A. As shown in FIG. 17, the strain sensor 8 is attached to the surface of the film outer package 5.
[0048]
【The invention's effect】
The thin battery and the battery pack incorporating the thin battery of the present invention have the advantage that it is possible to accurately detect that the internal pressure of the film exterior body has increased and to prevent the internal pressure from rising. This is because the thin battery of the present invention and the battery pack incorporating the thin battery have the strain sensor attached to the surface of the film outer package in which the power generation element is housed. The strain sensor attached to the surface of the film exterior body detects the deformation of the film exterior body. For this reason, when the internal pressure of the thin battery rises and the film exterior body expands, the film exterior body expands and changes its shape, and the strain sensor can detect the increase in the internal pressure by detecting the extension of the film exterior body. As described above, the thin battery and the battery pack according to the present invention, which detects the increase in the internal pressure of the battery with the strain sensor, can accurately detect the increase in the internal pressure of the battery and prevent the battery from entering a dangerous state. There is a feature that can be improved.
[0049]
In addition, the thin battery of the present invention and the battery pack incorporating the thin battery can detect an increase in the internal pressure without opening the fracture groove or the welded portion of the film outer package at a predetermined pressure as in the past. In addition to being able to detect an increase in internal pressure, there is a feature that can be reused when the internal pressure decreases to a normal state after the internal pressure has increased.
[Brief description of the drawings]
FIG. 1 is a plan view of a conventional thin battery.
2 is a cross-sectional view taken along line AA of the thin battery shown in FIG.
FIG. 3 is a perspective view of another conventional thin battery.
FIG. 4 is a plan view of a battery pack incorporating a thin battery according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view of a thin battery of the battery pack shown in FIG.
FIG. 6 is an enlarged perspective view showing an example of a strain sensor.
FIG. 7 is a circuit diagram of a detection circuit for detecting a strain sensor signal.
8 is a circuit diagram of the battery pack shown in FIG.
FIG. 9 is a circuit diagram of a battery pack according to another embodiment of the present invention.
10 is a perspective view showing a manufacturing process of the thin battery shown in FIG. 5. FIG.
11 is a cross-sectional view showing a manufacturing process of the thin battery shown in FIG.
12 is a sectional view showing a manufacturing process of the thin battery shown in FIG.
13 is a bottom view of the thin battery shown in FIG.
FIG. 14 is a plan view of a thin battery according to another embodiment of the present invention.
15 is a cross-sectional view of the thin battery shown in FIG.
16 is a perspective view showing a manufacturing process of the thin battery shown in FIG. 14;
FIG. 17 is a plan view of a thin battery according to another embodiment of the present invention.
18 is a cross-sectional view of the thin battery shown in FIG.
[Explanation of symbols]
1 ... Positive electrode
2 ... Negative electrode
3 ... electrolyte layer
4 ... Sealing part 4A ... Cylindrical sealing part
4B ... Current collecting terminal side sealing part
5 ... Film exterior 5A ... Laminate film
5a ... Aluminum foil
5b Polypropylene film
5c Polyethylene film
6 ... Current collector terminal
7 ... Power generation elements
8 ... Strain sensor
9 ... Insulation sheet
10 ... Wire
11 ... Detection circuit
12 ... Wheatstone bridge circuit
13 ... Amplifier
14 ... AC power supply
15 ... Control circuit
16 ... Cutoff switch
17 ... Switching element
18 ... Battery
19 ... Output terminal
20 ... Reset switch
21 ... Protection circuit
22 ... Fuse
23 ... Power switch
24 ... Heating resistance
25 ... Constant current circuit
26 ... Case
27. Overcharge and overdischarge prevention circuit
28 ... Pressure release means

Claims (3)

A thin battery in which a power generation element (7) having a positive electrode (1) and a negative electrode (2) is housed inside a film outer package (5), and protection that cuts off current when the internal pressure of the thin battery increases. In a battery pack comprising a circuit (21),
A strain sensor (8) having a protective circuit (21) attached to the surface of the film outer package (5), and a cutoff switch (16) for cutting off the current flowing to the battery by the output signal of the strain sensor (8) The deformation sensor (8) detects deformation due to an increase in internal pressure of the film outer package (5), and when the strain sensor (8) detects deformation of the film outer package (5), the cutoff switch (16) A battery pack with a built-in thin battery, which is configured to be turned off to cut off a battery current. A thin battery in which a power generation element (7) having a positive electrode (1) and a negative electrode (2) is housed inside a film outer package (5), and protection that cuts off current when the internal pressure of the thin battery increases. In a battery pack comprising a circuit (21),
The strain sensor (8) in which the protective circuit (21) is attached to the surface of the film outer package (5), the energizing switch (23) that is switched by the output signal of the strain sensor (8), and the energizing switch A heating resistor (24) whose energization state is controlled in (23), and a fuse (22) disposed in a position heated by the heating resistor (24) and connected in series with the battery (18) And
When the deformation due to an increase in internal pressure of the film outer package (5) is detected by the strain sensor (8), and the strain sensor (8) detects the deformation of the film outer package (5), the energization switch (23) is turned on and the heating resistance A pack containing a thin battery characterized by passing a heating current through (24), and the heating resistor (24) heated by the heating current blows the fuse (22) to cut off the battery current. battery.   The thin battery according to claim 2, wherein the protection circuit (21) is connected to a constant current circuit (25) for controlling a current flowing through the heating resistor (24) with the energization switch (23) turned on. Pack battery to play.

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