JP2001216883A - Protective element and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protective element and a battery pack, capable of surely preventing the charging and discharging by an excessive current, the charging or the like through an excessive voltage by applying the protective element in the battery pack, using, for example a lithium ion secondary battery cell, a lithium polymer secondary battery cell or the like. SOLUTION: A temperature fuse 4 is fused by the heating of a PTC element 5, or these elements are integrated to constitute a protective element, and the protective element is arranged on the charging and discharging path of the battery pack.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection element and a battery pack, and can be applied to, for example, a battery pack using a lithium ion secondary battery cell, a lithium polymer secondary battery cell, or the like. According to the present invention, the thermal fuse is blown by the heat generated by the PTC element, and these elements are integrated to form a protection element. Further, the protection element is arranged in the charge / discharge path of the battery pack. , Charging and discharging by excessive current,
It is possible to reliably prevent charging or the like due to excessive voltage.

[0002]

2. Description of the Related Art Conventionally, a secondary battery using a lithium ion secondary battery cell, a lithium polymer secondary battery cell, or the like has been used as a battery pack for a power source of a portable device or the like. In such a secondary battery, overcurrent and overdischarge are prevented by a protection circuit. On the other hand, for example, Japanese Unexamined Patent Application Publication No.
No. 8, JP-A-11-135090 proposes a method for preventing excessive current and abnormal heat generation with a simple configuration using a PTC (Positive Temperature Coefficient) element.

[0003] Here, the PTC element disclosed in these publications is configured such that electrodes are arranged on a polymer composition (hereinafter, referred to as a PTC element) obtained by mixing and molding a conductive material such as carbon and a polymer, and a lead wire is connected thereto. It is made by insulating PTC elements and electrodes. As shown in FIG. 18, the PTC element is a temperature-sensitive resistor having a positive temperature characteristic. When a current equal to or more than a predetermined current value (trip current) flows, the resistance value sharply changes due to a change in the internal structure. It increases (ie, is a trip) and limits the current flow due to this abrupt change in resistance.

[0004] This phenomenon is caused by the fact that the PTC element generates heat due to the current and rises in temperature, and the temperature rise causes a change in the resistance value of the PTC element. In this PTC element, if the current rises to a high resistance state due to a current higher than the trip current, even if the current flowing due to the increase in the resistance value decreases, as long as the reduced current flows, the PTC element has a high resistance. It is designed to be kept in a value state.

Thus, in the method disclosed in Japanese Patent Application Laid-Open No. Hei 6-13068, a PTC element is arranged in the path of the charging / discharging current, for example, when the terminals are short-circuited, when the terminals are erroneously attached to the charging device, or the like. Also, an excessive current is prevented from flowing through the secondary battery cells.

In the method disclosed in Japanese Patent Application Laid-Open No. 11-135090, a change in the resistance value of the PTC
Due to the temperature change of the C element, PTC
The element is thermally coupled to the secondary battery cell to prevent abnormal heating of the secondary battery cell.

[0007]

However, as described above, P
The method of protecting a secondary battery cell with a TC element has a practically insufficient problem.

That is, when this type of secondary battery is erroneously attached to a charging device and charging is started by a high voltage, the PTC element trips and the resistance value of the PTC element becomes a high resistance value. The voltage applied to the secondary battery cell is reduced, so that charging of the secondary battery cell due to overvoltage can be protected.

However, even in this case, the charging current is slightly supplied to the secondary battery cell, and the secondary battery cell gradually approaches full charge and the terminal voltage gradually increases. . Thus, in the method of protecting the secondary battery cell with the PTC element, for example, in a short time of about several tens of minutes, although charging by an overvoltage can be sufficiently prevented, there is a case where the battery is left for a long time. In the end, there was a problem that charging due to overvoltage of the secondary battery cell could not be prevented.

Further, in this type of secondary battery, an excessive current flows through the secondary battery cell, though temporarily, until an excessive current flows out and trips. On the other hand, in the case of the PTC element, even if the current flowing after tripping becomes small, as long as the reduced current flows, the state of the high resistance value is maintained. When the temperature of the element decreases, the resistance value returns to the original value.

As a result, in this type of secondary battery,
Although it is a short period, the charging may be repeated due to an excessive voltage, and the discharging due to an excessive current may be repeated.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a protection element and a battery pack capable of reliably preventing charging and discharging by an excessive current, charging by an excessive voltage, and the like. It is.

[0013]

According to a first aspect of the present invention, there is provided a temperature-sensitive resistor which is applied to a protection element, and when a flowing current increases to a predetermined value or more, a resistance value rapidly increases. Fusing the fusing member by heating the body,
Thereby, when the current flowing through the temperature-sensitive resistor increases to a predetermined current value or more, the current flowing through the fusing member is cut off.

According to the invention of claim 8, the protection element applied to the battery pack and disposed on the charge / discharge path includes:
When the flowing current increases to a predetermined value or more, a temperature-sensitive resistor having a positive temperature characteristic that rapidly increases the resistance value is connected in series with the temperature-sensitive resistor, and is melted at a temperature equal to or higher than a predetermined temperature to be charged and discharged. And a fusing member for shutting off.

According to a fourteenth aspect of the present invention, when applied to a battery pack, when a flowing current increases to a predetermined value or more, a temperature-sensitive resistor element, which is an element having a positive temperature characteristic and rapidly increases a resistance value, is provided. A fuse and a fuse are connected in series and arranged in a charge / discharge path, and the thermal fuse is blown by heating the temperature-sensitive resistor element, so that when the current flowing in the charge / discharge path increases to a predetermined current value or more, the charge / discharge path is opened. Cut off.

According to the first aspect of the present invention, when the current applied to the protection element increases to a predetermined value or more, the fusing member of the fusing member is heated by the heating of the temperature-sensitive resistor which rapidly increases the resistance value. When the current flowing through the thermal resistor increases beyond a predetermined current value, the current flowing through the fusing member is cut off, and the current is cut off with high sensitivity compared to the case where the current is cut off simply by fusing due to self-heating of the fusing member. Therefore, the present invention can be applied to, for example, a battery pack with a simple configuration, thereby reliably preventing charging and discharging due to excessive current, charging due to excessive voltage, and the like.

According to the eighth aspect of the present invention, when applied to a battery pack, the protection element disposed in the charging / discharging path causes the resistance value to rapidly increase when the flowing current increases to a predetermined value or more. A temperature-sensitive resistor, and a fusing member that is connected in series with the temperature-sensitive resistor and that melts at a temperature equal to or higher than a predetermined temperature and shuts off a charging / discharging path. The current can be cut off with higher sensitivity than when the current is cut off,
With such a simple configuration, charging and discharging due to excessive current, charging due to excessive voltage, and the like can be reliably prevented.

Further, according to the present invention, when applied to a battery pack, when the flowing current increases to a predetermined value or more, the temperature-sensitive resistor element which is a positive temperature characteristic element that rapidly increases the resistance value is provided. A thermal fuse is connected in series and placed in the charge / discharge path. If the current flowing through the charge / discharge path increases to a predetermined current value or more due to the blowing of the thermal fuse due to heating of the temperature-sensitive resistor element, the charge / discharge path is cut off. By doing so, it is possible to cut off the current with high sensitivity as compared to the case where the current is cut off simply by self-heating in the thermal fuse, and charge and discharge with an excessive current, charge with an excessive voltage, etc. Can be reliably prevented.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 1 is a sectional view showing a battery pack according to a first embodiment of the present invention. The battery pack 1 is formed by housing a secondary battery cell 3 and the like in a case 2.

Here, the case 2 is formed by, for example, injection molding a resin material so that a positive external terminal 2a and a negative external terminal 2b for inputting / outputting a charging / discharging current to / from an external device are provided at predetermined positions. It has been done.

The secondary battery cell 3 is a lithium ion battery in which a material containing manganese is applied to a positive electrode material.
The outer shape is formed by a substantially prismatic shape. In the secondary battery cell 3, an outer can is formed of iron and is set as the positive electrode 3a, and the negative electrode 3b is arranged on the upper surface of each prism. Here, the lithium ion battery in which the material containing manganese is applied to the positive electrode material as described above is characterized by high safety against excessive voltage charging.

In the secondary battery cell 3, the positive electrode 3a is connected to the positive external terminal 2a of the battery pack 1 through a series circuit of the temperature fuse 4 and the PTC element 5, while the negative electrode 3b is connected to the battery pack 1 Is connected directly to the negative external terminal 2b. As a result, in the battery pack 1, the internal circuit is represented by a connection diagram as shown in FIG. 2, and the charging power supplied through the positive external terminal 2a and the negative external terminal 2b is supplied to the secondary battery cell 3, Further, the electrodes of the secondary battery cells 3 can be output to an external device.

The thermal fuse 4 is, for example, an integral thermal fuse. As shown in FIG. 3, the thermal fuse 4 is melted at a predetermined temperature between the electrode metal plates 4a and 4b which are held so as to face each other. Thus, a fusing member 4c for interrupting the electrical connection between the electrode metal plates 4a and 4b is arranged and configured. Thereby, the thermal fuse 4 is connected to the fusing member 4c.
When the fusing member 4c is heated to a predetermined temperature or higher due to an increase in the current flowing through the fusing member 4c, and further when the fusing member 4c is heated to a predetermined temperature or higher, the charge / discharge current path of the secondary battery cell 3 is cut off. ing. The temperature fuse is not limited to the integral type, and various types can be widely applied.

On the other hand, similarly, the PTC element 5 has electrode metal plates 5a and 5b which are held so as to partially face each other.
The PTC element 5c is arranged between the electrode metal plates 5a and 5b, and the PTC element 5c is arranged between the electrode metal plates 5a and 5b.

The PTC element 5 is, for example, several tens of times less than the rated current based on the rated charge / discharge current of the secondary battery cell 3.
A current that is as high as [%] is set as the trip current. Thereby, in this battery pack 1,
When an excessive current exceeding the rated current flows to the secondary battery cell 3, the PTC element 5 is tripped, and this current is limited.

Here, the thermal fuse 4 and the PTC element 5 are designed so that the heat generated by the PTC element 5c of the PTC element 5 is quickly transmitted to the thermal fuse 4 without waste, that is, the thermal fuse 4 and the PTC element 5 are thermally connected. They are connected so that they are strongly coupled.

More specifically, the thermal fuse 4 and the PTC element 5 are connected to the metal electrodes 4a, 4b, 5a, and 5b so that heat radiation at the metal electrodes 4a, 4b, 5a, and 5b is reduced.
And 5b have a small surface area and a necessary and sufficient cross-sectional area;
It is formed by length. In particular, thermal fuse 4 and PTC
The metal electrodes 4b and 5a on the side connecting the element 5 are formed to be short in length, so that the heat generated by the PTC element 5 is quickly transmitted to the thermal fuse 4, and furthermore, the thermal fuse 4 and the PTC element 5 And can be held close to each other. The connection between the thermal fuse 4 and the PTC element 5 is performed by, for example, electric resistance welding, soldering, ultrasonic welding, or the like.

Further, the thermal fuse 4 and the PTC element 5
Are integrally held on the side surface of the secondary battery cell 3 by, for example, a silicon-based adhesive which is an insulating adhesive having a high thermal conductivity. Thus, the heat generated by the PTC element 5 is quickly transmitted to the thermal fuse 4 by the heat conduction of the adhesive between the thermal fuse 4 and the PTC element 5.

In this embodiment, the thermal fuse 4
Is thermally strongly connected to the PTC element 5 in this manner, so that in addition to the temperature rise due to the heat generated by the fusing member 4c itself, the fusing member 4c is also heated by the PTC element 5.
Are configured to rise in temperature. Thermal fuse 4
The characteristics of the fusing member 4c are selected so that when a trip current that trips the PTC element 5 flows through the secondary battery cell 3 due to the temperature rise due to these, the fusing member 4c is melted.

Specifically, in this embodiment, the temperature is 9
A fusing member 4c having a characteristic of fusing at 0 degrees is applied. As the thermal fuse 4, a fuse having a rated current value larger than the rated current value of the PTC element 5 is applied, and a fuse having a fusing current value larger than the trip current value of the PTC element 5 is applied. .

(1-2) Operation of First Embodiment In the above configuration, in the battery pack 1 (FIGS. 1 and 2), for example, when connected to a charging device, the positive external terminal 2a and the negative external terminal 2b, a charging current is supplied from the charging device, and this charging current is supplied to the secondary battery cell 3. Also, for example, when connected to a portable device, the power of the secondary battery cell 3 is supplied to the external device via the positive external terminal 2a and the negative external terminal 2b, whereby the external device can be driven.

On the other hand, when the battery pack is erroneously connected to a charger for charging another battery pack and power supply is started with a voltage higher than that of this charger as shown in FIG. An excessive voltage is applied to the secondary battery cell 3, and an excessive current I flows through the thermal fuse 4 and the PTC element 5 (FIGS. 4C and 4D).

As a result, in the thermal fuse 4, the current I causes the fusing member 4c itself to generate heat.
The temperature of c gradually rises. Further, in the PTC element 5, the PTC element 5c generates heat, and the generated heat further increases the temperature of the fusing member 5c of the thermal fuse 4. (FIG. 4
(A) and (B)).

The PTC element 5 is switched to the trip state about one second after charging is started in this embodiment due to the temperature rise of the PTC element 5c due to the heat generated by the PTC element 5c. Thereby, in the battery pack 1,
After starting excessive charging, the charging current can be limited in a short period of time, and damage to the secondary battery cell 3 can be prevented.

Even after the charging current is limited in this manner, the temperature of the fusing member 4 of the thermal fuse 4 gradually increases until the temperature of the fusing member 4 reaches 90 ° C. Rises, the fusing member 4 is blown, and the connection between the metal electrodes 4a and 4b of the thermal fuse 4 is cut off, whereby the supply of power to the secondary battery cell 3 is completely cut off.

As a result, in the battery pack 1, an excessive charging current can be cut off with higher accuracy as compared with a case where the charging / discharging current is cut off simply by the self-heating of the thermal fuse. In addition, the charging of the secondary battery cell with a small current, such as the case where the charging current is simply limited by the PTC element 4, can be stopped, and the charging with an excessive voltage can be reliably prevented.

Further, since the charging path is completely cut off by the thermal fuse 4, the supply of the charging current to the secondary battery cell 3 is prevented when the charging device is erroneously mounted again. Can be. As a result, it is possible to prevent a repetition of charging with an excessively short voltage in a case where an excessively large current is suppressed only by the PTC element alone.

On the other hand, for example, the external electrode terminals 2a, 2a
When an excessive discharge current flows due to a metal or the like erroneously coming into contact with b, also in this case, the discharge path is completely cut off by the thermal fuse 4 due to the excessive voltage as in the case of charging. This prevents discharge due to excessive current.

In the example of FIG. 4, a PTC element 5 having a rated current value of 2 [A], a trip current value of 3 [A], and an initial resistance of 50 [mΩ] was used. The temperature fuse 4 has a rated current value of 3 [A], a breaking current value of 4 [A], and a fusing temperature of 90 degrees. The secondary battery cell 3 has a rated charging voltage value of 4.2 [V]. And a battery having a rated charging current value of 2 [A]. The ambient temperature at the time of the measurement was about 25 degrees, and the case where the battery was charged with a DC power supply of 6 [V] and 4 [A].

(1-3) Effects of the First Embodiment According to the above configuration, the PTC element and the thermal fuse are thermally connected, and the fusing member is generated by the heat generated by the fusing member and the heat generated by the PTC element. By fusing and interrupting the charge / discharge current of the secondary battery cell, it is possible to reliably prevent charging / discharging due to excessive current and charging due to excessive voltage with a simple configuration.

In particular, the manganese-based lithium ion secondary battery cell according to the configuration of this embodiment has a comparatively large margin for excessive voltage charging and discharging. And simply a thermal fuse and P
The secondary battery cell 3 can be protected by the combination with the TC element, and the secondary battery cell 3 can be easily and reliably protected, and the configuration of the entire battery pack can be simplified accordingly.

(2) Second Embodiment FIG. 5 shows, in comparison with FIG. 3, a thermal fuse and a P which are applied to a battery pack according to a second embodiment of the present invention.
It is sectional drawing which shows the combination with a TC element. Here, the thermal fuse 4 and the PTC element 15 are sequentially laminated via an adhesive from the secondary battery cell 3 side, and are integrally held by the secondary battery cell 3. As a result, the thermal fuse 4 and the PTC element 15 are thermally strongly coupled.

The PTC element 15 is arranged in the secondary battery cell 3 in such a stacked arrangement, and the electrode metal plates 15a, 15b are drawn out from the same direction so that the heat radiation due to the wiring is reduced. It is configured to be.
The connection of the thermal fuse 4 and the PTC element 15 is similar to that of the first embodiment.
Is configured to be able to efficiently and quickly transmit the temperature rise to the thermal fuse.

As shown in FIG. 5, thermal fuse 4, PT
The same effect as in the first embodiment can be obtained by laminating and thermally coupling the C element 15.

(3) Third Embodiment FIG. 6 shows, in comparison with FIG. 3, a thermal fuse and a P which are applied to a battery pack according to a third embodiment of the present invention.
It is sectional drawing which shows the combination with a TC element. Here, the thermal fuse 4 and the PTC element 5 are arranged in the secondary battery cell 3 in the same manner as in the first embodiment. Further, the thermal fuse 4 and the PTC element 5 are on the opposite side of the secondary battery cell 3,
A plate material 20 such as a metal having a high thermal conductivity is bonded and held by an adhesive having a high thermal conductivity. As a result, FIG.
In the configuration shown in (1), the heat of the PTC element 5 can be more efficiently transmitted to the thermal fuse 4.

According to the structure shown in FIG. 6, the heat generated by the PTC element 5 can be more efficiently conducted to the thermal fuse 4 as compared with the above-described embodiment. In addition to the effect of thermal fuse 4
Can be raised to the fusing temperature in a short time, and the charge / discharge path can be cut off in a short time.

(4) Fourth Embodiment FIG. 7 is a sectional view showing a protection element applied to a battery pack according to a fourth embodiment of the present invention in comparison with FIG. This protection element 25 is arranged in the secondary battery cell 3 instead of the above-described combination of the thermal fuse and the PTC element.

Here, the protection element 25 is formed of the internal electrode metal plate 2
6, a fusing member 4c and a PTC element 5c are arranged on both surfaces, respectively, and the fusing member 4c and the PTC element 5c are connected in series to external electrode metal plates 25a and 25b. As a result, the protection element 25 is formed by integrating the PTC element and the thermal fuse by series connection, and the PTC element 5c that constitutes the PTC element and the fusing member 4c that constitutes the thermal fuse are more strongly thermally bonded. It is made to combine.

On the side of the fusing member 4c, the protection element 25 is provided with the internal electrode metal plate 26 and the external electrode metal plate 2 in the same direction.
5a holds the fusing member 4c. In addition, with respect to such a point that a thermally strong connection is made, the fusing member 4c, PT
It is desirable that the C elements 5c are held so as to face each other and are in contact with the internal electrode metal plate 26 with a large area.

According to the configuration shown in FIG. 7, even if a protection element having a configuration in which a PTC element and a thermal fuse connected in series are integrated is used instead of the PTC element and the thermal fuse, the first embodiment The same effect as in the embodiment can be obtained. Further, since the thermal connection between the fusing member 4c and the PCT element 5c can be strengthened, the temperature of the fusing member 4c can be raised to the fusing temperature in a short time, and the charge / discharge path can be cut off in a short time.

(5) Fifth Embodiment FIG. 8 is a sectional view showing a protection element applied to a battery pack according to a fifth embodiment of the present invention in comparison with FIG. This protection element 35 is arranged in the secondary battery cell 3 instead of the above-described combination of the thermal fuse and the PTC element.

Here, the protection element 35 is formed of the external electrode metal plate 3.
Between 5a and 35b, PTC element 5c, internal electrode 36,
It is formed by a structure in which a PTC element and a thermal fuse by series connection are integrated by a structure in which the fusing members 4c are sequentially laminated.

According to the configuration shown in FIG. 8, the fusing member 4c,
PTC elements 5c are stacked and arranged, and PT
The same effect as in the first embodiment can be obtained even if a protection element having a configuration in which the C element and the thermal fuse are integrated is used. Further, since the thermal connection between the fusing member 4c and the PCT element 5c can be strengthened, the temperature of the fusing member 4c can be raised to the fusing temperature in a short time, and the charge / discharge path can be cut off in a short time.

(6) Sixth Embodiment FIG. 9 is a sectional view showing a protection element applied to a battery pack according to a sixth embodiment of the present invention in comparison with FIG. This protection element 45 omits the internal electrode 36 of the protection element 35 described in the fifth embodiment,
It is formed by a structure in which the PTC element 5c and the fusing member 4c are directly laminated, and has a configuration in which the PTC element and the thermal fuse by series connection are integrated.

According to the configuration shown in FIG. 9, the fusing member 4c,
By directly laminating and arranging the PTC elements 5c, the thermal connection between the fusing member 4c and the PTC element 5c can be further strengthened, and the same effect as in the first embodiment can be obtained. In addition, the charge / discharge path can be cut off in a short time.

(7) Seventh Embodiment FIG. 10 is a sectional view showing a protection element applied to a battery pack according to a seventh embodiment of the present invention in comparison with FIG. In the protection element 55, the fusing member 4c and the PTC element 5c are arranged separately on the side surface of the secondary battery cell 3 of the internal electrode 56, and the fusing member 4c and the PTC element 5c are connected in series to the external electrode metal plates 55a and 55b. Created by the configuration connected to Thus, the protection element 55 is formed by a configuration in which the PTC element and the thermal fuse connected in series are integrated.

According to the structure shown in FIG.
c, the same effect as in the first embodiment can be obtained even if the protection element is formed by arranging the PTC elements 5c side by side and by integrating the PTC element and the thermal fuse by series connection. it can. In addition, the thermal connection between the fusing member 4c and the PTC element 5c can be strengthened by integration, so that the charging / discharging path can be cut off in a shorter time than in the first embodiment, and the overall shape can be reduced. The thickness can be reduced.

(8) Eighth Embodiment FIG. 11 is a sectional view showing a protection element applied to a battery pack according to an eighth embodiment of the present invention in comparison with FIG.

The protection element 65 has the same structure as that of the protection element 55 according to the eighth embodiment, and has a heat conductivity on the surface of the internal electrode 66 opposite to the fusing member 4c and the PTC element 5c. A plate material 47 such as a high metal is connected. As a result, the protection element 65 becomes even more thermally strong,
c, PTC element 5c side.

According to the structure shown in FIG. 11, the fusing member 4c and the PTC element 5c are arranged side by side on one surface of the internal electrode metal plate 66, and the plate 67 made of metal or the like having high thermal conductivity is arranged. In addition to the same effects as in the embodiment 8, the charging / discharging path can be cut off in a much shorter time.

(9) Ninth Embodiment FIG. 12 is a sectional view showing a protection element applied to a battery pack according to a ninth embodiment of the present invention in comparison with FIG. This protection element 75 is arranged in the secondary battery cell 3 instead of the above-described combination of the thermal fuse and the PTC element.

The protection element 75 has a fusing member 4c and a PTC element 5c arranged side by side on an internal electrode metal plate 76 in the same direction as one of the external electrode metal plates 75a. It is created by a configuration in which the member 4c and the PTC element 5c are connected in series. As a result, the protection element 75 is formed by a configuration in which the PTC element and the thermal fuse connected in series are integrated.

According to the structure shown in FIG. 12, the fusing member 4c and the PTC element 5c are arranged side by side on the internal electrode metal plate 76 from the same direction as the one external electrode metal plate 75a, and the PTC element and the thermal fuse are connected in series. The same effect as in the above-described embodiment can be obtained even if a protection element is formed by a configuration in which is integrated.

(10) Tenth Embodiment FIG. 13 is a sectional view showing a protection element applied to a battery pack according to a tenth embodiment of the present invention in comparison with FIG. This protection element 85 is arranged in the secondary battery cell 3 instead of the above-described combination of the thermal fuse and the PTC element.

Here, the protection element 85 includes the internal electrode 8 in addition to the structure of the protection element described in the ninth embodiment.
6 is formed on the opposite side to a plate material 87 made of metal or the like having high thermal conductivity. The protection element 85 connects the plate member 87 and the fusing member 4c via the insulating sheet 87.

According to the configuration shown in FIG. 13, the fusing member 4c and the PTC element 5c are arranged side by side on one surface of the internal electrode metal plate 86, and the plate 87 made of metal or the like having high thermal conductivity is arranged. In addition to the same effects as in the embodiment 9, the charging / discharging path can be cut off in a much shorter time.

(11) Eleventh Embodiment FIG. 14 is a sectional view showing a protection element applied to a battery pack according to an eleventh embodiment of the present invention in comparison with FIG. This protection element 95 is arranged in the secondary battery cell 3 instead of the above-described combination of the thermal fuse and the PTC element.

In the protection element 95, the internal electrode metal plates 95a and 95b are abutted at a predetermined interval, and the fusing member 4 is provided between the electrode metal plates 95a and 95b.
c, PTC element 5c is arranged.

As shown in FIG. 14, a fusing member 4c and a PTC element 5c are arranged between butted internal electrode metal plates 95a and 95b, and a PTC element and a thermal fuse are integrated to form a protection element. However, the same effect as in the above-described embodiment can be obtained. Further, the fusing member 4c and the PTC are provided between the butted electrode metal plates 95a and 95b.
By arranging the element 5c, the overall shape can be reduced in size and thickness.

(12) Twelfth Embodiment FIG. 15 is a sectional view showing a battery pack according to a twelfth embodiment of the present invention in comparison with FIG. As the battery pack 101, a secondary battery cell 103 in which an outer can is assigned to a negative electrode is applied.
Between the negative electrode terminal 103b and the negative external terminal 2b of the protection element 25 (35 to 95) or the thermal fuse described above and the PT.
A series circuit of C elements is arranged.

As shown in FIG. 15, when the secondary battery cell 103 in which the outer can is assigned to the negative electrode is applied and the protection element 25 (35 to 95) and the like are arranged in the negative charge / discharge path, The same effects as in the above-described embodiment can be obtained.

(13) Thirteenth Embodiment FIGS. 16 and 17 are a sectional view and a connection diagram showing a battery pack according to a thirteenth embodiment of the present invention in comparison with FIGS. is there. This battery pack 111
Inputs and outputs a charge / discharge current through the protection circuit 112.
Here, the protection circuit 112 monitors the charging / discharging current, and when the charging / discharging current increases to a predetermined value or more, the protection circuit 112 cuts off the charging / discharging path by controlling the field-effect transistor, the relay, and the like.
Thereby, the secondary battery cells 3 are protected.

As shown in FIGS. 16 and 17, when the present invention is applied to the case where the secondary battery cell 3 is held by the protection circuit 112, the charging of the secondary battery cell 3 by an excessive voltage can be more reliably prevented. And reliability can be improved accordingly.

(14) Other Embodiments In the above-described embodiment, the separately formed P
The case where the TC element and the thermal fuse are arranged in the secondary battery cell, and the case where the protective element formed by integrating the PTC element and the thermal fuse are arranged in the secondary battery cell have been described. The present invention is not limited to this, and these may be integrated with the secondary battery cells.

In the above embodiment, when the flowing current increases to a predetermined value or more, a conductive material such as carbon and a polymer are mixed as a temperature-sensitive resistor having a positive temperature characteristic to rapidly increase the resistance value. The molded polymer composition is
Although the description has been given of the case where the present invention is applied to the TC element, the present invention is not limited thereto, and members having various positive temperature characteristics exhibiting similar characteristics can be widely applied.

Further, in the above embodiment, the case where the present invention is applied to a battery pack using a lithium ion battery in which a material containing manganese is applied to the positive electrode material has been described, but the present invention is not limited to this. Widely applied to battery packs of various secondary batteries such as a lithium ion battery using a positive electrode material according to another configuration, and further, a lithium polymer secondary battery, a lithium secondary battery, a nickel cadmium secondary battery, and a nickel hydride secondary battery. be able to.

In the above embodiment, the case where the protection element is applied to the battery pack has been described.
The present invention is not limited to this, and can be widely applied to various electronic devices such as a charging device. In this case, if necessary, the fusing member and the PTC element may be arranged in separate current paths.

[0079]

As described above, according to the present invention, the thermal fuse is blown by the heat of the PTC element, and these elements are integrated to form a protective element. By placing the battery pack in the charge / discharge path, charging / discharging due to excessive current,
Charging due to excessive voltage can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a battery pack according to a first embodiment of the present invention.

FIG. 2 is a connection diagram illustrating the battery pack of FIG. 1;

FIG. 3 is a sectional view showing a PTC element and a thermal fuse applied to the battery pack of FIG. 1;

FIG. 4 is a characteristic curve diagram for explaining the operation of the battery pack of FIG. 1;

FIG. 5 is a sectional view showing a PTC element and a thermal fuse applied to a battery pack according to a second embodiment.

FIG. 6 is a sectional view showing a PTC element and a thermal fuse applied to a battery pack according to a third embodiment.

FIG. 7 is a sectional view showing a protection element applied to a battery pack according to a fourth embodiment.

FIG. 8 is a sectional view showing a protection element applied to a battery pack according to a fifth embodiment.

FIG. 9 is a sectional view showing a protection element applied to a battery pack according to a sixth embodiment.

FIG. 10 is a sectional view showing a protection element applied to a battery pack according to a seventh embodiment.

FIG. 11 is a sectional view showing a protection element applied to a battery pack according to an eighth embodiment.

FIG. 12 is a sectional view showing a protection element applied to a battery pack according to a ninth embodiment.

FIG. 13 is a sectional view showing a protection element applied to a battery pack according to a tenth embodiment.

FIG. 14 is a sectional view showing a protection element applied to a battery pack according to an eleventh embodiment.

FIG. 15 is a sectional view showing a battery pack according to a twelfth embodiment.

FIG. 16 is a sectional view showing a battery pack according to a thirteenth embodiment.

17 is a connection diagram of the battery pack of FIG.

FIG. 18 is a characteristic curve diagram showing characteristics of a PTC element.

[Explanation of symbols]

1, 101, 111 ... battery pack, 3, 103 ...
... Secondary battery cell, 4 ... Temperature fuse, 4a ... Fusing member, 5, 15 ... PTC element, 5a ... PTC element, 2
5, 35, 45, 55, 65, 75, 85, 95 ... Protecting element

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Yamadaira 1-1 Shimosugishita, Takakura, Hiwada-cho, Koriyama-shi, Fukushima Prefecture Inside Sony Energy Tech Co., Ltd. No. 1 Shimosugishita, Tamachi Takakura Sony Energy Tech Co., Ltd. F term (reference) 5E034 AA08 BB01 DA02 DD03 5G502 AA02 AA11 EE06 FF08 5H022 AA09 AA19 CC09 CC12 CC16 KK01 5H030 AA03 AA04 AS06

Claims (17)

[Claims] When a flowing current increases to a predetermined value or more, a temperature-sensitive resistor having a positive temperature characteristic that rapidly increases a resistance value is melted at a temperature equal to or higher than a predetermined temperature, and electrical connection between predetermined electrodes is established. A fusing member that cuts off the current, the current flowing through the fusing member is cut off when the current flowing through the temperature-sensitive resistor increases to a predetermined current value or more due to the fusing of the fusing member by heating the temperature-sensitive resistor. A protection element characterized by the above-mentioned. 2. The protection element according to claim 1, wherein said temperature-sensitive resistor and said fusing member are connected in series. 3. The protection element according to claim 2, wherein said temperature-sensitive resistor and said fusing member are laminated. 4. The protection element according to claim 2, wherein the temperature-sensitive resistor and the fusing member are laminated while being insulated. 5. The method according to claim 1, wherein said temperature-sensitive resistor and said fusing member are arranged side by side on a predetermined electrode material, and said temperature-sensitive resistor and said fusing member are connected in series by said electrode material. The protection element according to claim 2, wherein 6. The fusing member according to claim 2, wherein the fever is thermally coupled to the fusing member by a heat conducting member that conducts heat generated by the temperature sensing resistor to the fusing member. Protection element. 7. The protection element according to claim 6, wherein said heat conducting member is an adhesive. 8. A battery pack in which a predetermined protection element is arranged in a charge / discharge path, wherein the protection element has a positive temperature characteristic temperature-sensitive characteristic in which when a flowing current increases to a predetermined value or more, a resistance value increases rapidly. And a fusing member that is connected in series with the temperature-sensitive resistor, is heated by the temperature-sensitive resistor, melts at a temperature equal to or higher than a predetermined temperature, and cuts off the charge / discharge path. Battery pack. 9. The battery pack according to claim 8, wherein said temperature-sensitive resistor and said fusing member are laminated. 10. The battery pack according to claim 9, wherein the temperature-sensitive resistor and the fusing member are laminated while being insulated. 11. A method according to claim 11, wherein said temperature-sensitive resistor is provided on a predetermined electrode material.
The battery pack according to claim 9, wherein the fusing member is arranged side by side, and the temperature-sensitive resistor and the fusing member are connected in series by the electrode material. 12. The temperature sensing resistor and the fusing member are thermally coupled by a heat conducting member that conducts heat generated by the temperature sensing resistor to the fusing member.
The battery pack according to 1. 13. The battery pack according to claim 12, wherein said heat conducting member is an adhesive. 14. A battery pack in which a temperature-sensitive resistor element and a temperature fuse are connected in series and arranged in a charging / discharging path, wherein when the current flowing through the temperature-sensitive resistor increases to a predetermined value or more, the battery pack abruptly increases. The temperature fuse is a temperature fuse that melts the fusing member at a temperature equal to or higher than a predetermined temperature and cuts off the charging / discharging path. A battery pack characterized in that when a current flowing through the charge / discharge path increases to a predetermined current value or more due to blowing of the thermal fuse due to heating, the charge / discharge path is cut off. 15. The battery pack according to claim 14, wherein said temperature-sensitive resistor element and said thermal fuse are laminated. 16. The temperature sensing resistor element and the temperature fuse are thermally coupled by a heat conducting member that conducts heat generated by the temperature sensing resistor element to the temperature fuse. The battery pack according to 1. 17. The battery pack according to claim 16, wherein said heat conducting member is an adhesive.