JP2003077456A - Protection element and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery with a protection element that has small space factor and is superior in safety. SOLUTION: The battery 1 comprises a battery container 2 that houses a generating element containing a positive and a negative electrodes and is connected to its first electrode (positive electrode), a conductive terminal board 4 that is connected to the second electrode (negative electrode) and is provided on one face of the battery container so as to close fluid-tight the battery container through an insulating material 3, and a protection element 5 that has two conductive plates 51, 53 which are mutually conducted at normal state and its first conductive plate 51 is conducted to the negative electrode and at the abnormal state those conductive plates are electrically cut off. The first conductive plate is connected to the terminal board and the second conductive plate constitutes a terminal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective element and a battery, and can be suitably used for a battery, such as a lithium ion battery, which is small and requires safety.

[0002]

2. Description of the Related Art A small battery such as a lithium secondary battery is built in a small device such as a mobile phone together with a battery protection device such as a PTC device, a fuse and a thermal protector. In a conventional battery, a battery cell includes a power generating element including positive and negative electrodes, and a battery container made of, for example, aluminum that houses the power generating element. The first electrode (for example, positive electrode) of the power generation element is connected to the container, and the second electrode (for example, negative electrode) is connected to the negative electrode terminal that penetrates the lid of the container and is exposed to the outside of the container. In this case, the container also serves as the positive electrode terminal.

In the PTC element, the protective element is a PTC material whose resistance rapidly rises in the event of abnormalities such as overcurrent and heat generation.
The fuse contains a fusible material that melts in the event of an abnormality, and the thermal protector contains a bimetal material that reverses and separates from the contact in the event of an abnormality. Both of them always have two conductive plates that conduct each other through these variable materials. .

Conventionally, the protective element is generally mounted on a substrate separate from the container, one conductive plate is connected to one of the electrodes, and the other conductive plate is separated from the electrode. Alternatively, it is also known that the battery container also serves as a positive electrode terminal, the protective element is directly mounted on the battery container, and one conductive plate is connected to the battery container via a lead.

[0005]

However, in the structure of the conventional battery with a protective element, the substrate on which the protective element is mounted prevents the miniaturization of the whole. Also, in the case of the configuration in which the protective element is directly mounted on the battery container, the negative electrode terminal is exposed, so conductive parts and debris such as nails and metal pins that exist near the battery without the user being aware of it are protected. There is also a possibility that the negative electrode terminal and the battery case may be short-circuited without going through the element.
Therefore, an object of the present invention is to provide a battery having a small occupied volume and excellent safety.

[0006]

In order to solve the problem, the battery of the present invention accommodates a power generating element including positive and negative electrodes, a battery container connected to the first electrode, and a second battery container. A conductive terminal block that is connected to the electrodes and is provided on one surface of the battery container so as to liquid-tightly seal the battery container via an insulating material, and two conductive plates and a material with variable physical properties arranged between the conductive plates. And a protection element configured to conduct two conductive plates at all times and cut off in the event of an abnormality, the first conductive plate being connected to a conductive terminal block, and the second conductive plate serving as a terminal. It is characterized by

According to this invention, since the first conductive plate of the protection element is connected to the conductive terminal block, the volume occupied by the entire battery is small. Then, the second conductive plate of the protection element is used as a terminal connected to the external circuit. Therefore, when a short circuit occurs outside the battery, the short-circuit current always passes through the protection element, which is safe.

The variable physical property material is, for example, a PTC material, a bimetal material or a fusible material. In this case, 2
An insulating support is preferably provided between two conductive plates. As a result, the conductive plate is backed to the insulative support, so the second conductive plate must surely hit the pin-shaped contact terminals (pogo pins) and pads provided on the device side to secure the connection with the external circuit. Because you can The insulating support is made of, for example, ceramic or heat resistant resin.

[0009]

Therefore, a suitable protective element for use in the battery with the protective element of the present invention has two conductive plates which are normally connected to each other via the physical property changing material, and the conductive plate is changed due to the change of the physical property of the physical property changing material at abnormal time. In the protection element in which the gap is cut off, an insulating support that fixes the distance between the conductive plates with mechanical strength higher than that of the physical property variable material is provided between the two conductive plates.

The present invention can be suitably applied to a lithium secondary battery. In this case, as the power generation element, for example, a positive electrode plate coated with an active material material such as lithium cobalt oxide, a separator holding an organic electrolyte solution containing a lithium salt, and a negative electrode plate coated with a host material such as carbon There is one that is laminated in order and wound in a spiral shape. A polymer material may be used for the electrodes, and a polymer solid electrolyte may be used instead of the organic electrolyte solution. As the battery container, for example, a rectangular container made of aluminum can be used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 An embodiment of a battery with a protective element of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a main part of a battery with a protective element according to an embodiment, and FIG. 2 is an enlarged sectional view of a thermal protector.

The battery 1 includes a power generating element (not shown) composed of positive and negative electrode plates facing each other with a separator interposed therebetween, a container 2 made of aluminum for accommodating the power generating element, and a not shown electrolytic cell filled in a gap in the container. Liquid and lid 21 which is one end surface of container 2
A conductive terminal block 4 fixed via an insulating sealing material 3 at approximately the center of the above, and a thermal protector 5 mounted on the conductive terminal block 4. A hole 7 for releasing pressure is formed at an eccentric position of the lid 21, and the lid 2 including the hole 7 is included.
An aluminum thin film 8 is formed on the entire inner surface of 1. Therefore, the lid 21 functions as a thin-walled rupture valve only at the position of the hole 7, and when the internal pressure of the container 2 rises, the thin film 8 ruptures at the position of the hole 7 to prevent explosion.

In the container 2, the positive electrode plate is connected to the inner surface of the container 2. The conductive terminal block 4 is made of metal and has a T-shaped cross section in which a flat plate 42 is attached to one end surface of a cylinder 41. The cylinder 41 is embedded in the container 2 and connected to a negative electrode by a lead (not shown). The flat plate 42 is out of the container 2.

The thermal protector 5 is opposed to the lower plate 51 via a metal lower plate 51, a frame 52 disposed on the lower plate 51 and made of an insulating material smaller than the lower plate 51, and a frame 52 slightly smaller than the frame 52. Metal upper plate 53, lower plate 51 frame 52
The contact 54 and one end welded to the area surrounded by
3 and a bimetal piece 55 sandwiched between the frame 52. The thermal protector 5 is fixed on the conductive terminal block 4 by bonding the back surface of the lower plate 51 to the entire surface of the flat plate 42. Therefore, the lower plate 51 is a conductive plate that serves as a connection point with the conductive terminal block 4, and the upper plate 53 is a conductive plate that serves as a terminal with an external circuit (not shown).

The thermal protector 5 includes a lower plate 51, a frame 52, and an upper plate 53 which are overlapped with each other, and the lower plate 5 protruding from the frame 52.
It is manufactured by bending the outer edge of 1 and sandwiching the frame 52 and the upper plate 53, and caulking. The bimetal piece 55 may be fixed to the upper plate 53 in advance by welding or the like, but it may be fixed at the same time when caulking. The central portion of the upper plate 53 is bulged upward, so that the space between the opposing surfaces of the lower plate 51 and the upper plate 53 is larger than the thickness of the frame 52.
The free end of the bimetal piece 55 is located between the facing surfaces,
Normally, only the lower plate 51 and the contact 54 are in contact with each other.

The seal member 3 is made of resin and has a T-shaped cross section that follows the outer shape of the combination of the conductive terminal block 4 and the thermal protector 5. It is adhered to both the container 2 and the conductive terminal block 4, and the lower plate. It covers most of the portion of the plate 51 that extends beyond the flat plate 42. Therefore, the upper plate 53 is substantially the only exposed portion having the same potential as the conductive terminal block 4. At the eccentric position on the opposite side of the hole 7 of the lid 21, a region as the positive electrode terminal face 22 is determined with a predetermined distance from the conductive terminal block 4, and the region except this region and the upper plate 53 are exposed. The whole 21 is covered with a covering material 6 made of an insulating resin.

When the battery 1 is used as a power source for a device or is charged, the upper plate 53 is used as a negative electrode terminal on the battery 1 side, and the positive electrode contact terminal and the negative electrode contact terminal of the device or the charger are respectively positive electrode terminals. The surface 22 and the upper plate 53 are applied to be discharged or charged. Since the entire surface of the flat plate 42, which is the outer portion of the container 2 of the conductive terminal block 4, is covered with the thermal protector 5, the current always passes through the bimetal piece 55. At the time of overcurrent or heat generation, the heat inside the container 2 is quickly transferred to the bimetal piece 55 via the conductive terminal block 4, whereby the bimetal piece 55 is inverted and separated from the contact 54 to interrupt the current. Further, when the battery 1 is outside the device, only the upper plate 53 is exposed on the negative electrode side, so that the external short-circuit current always passes through the bimetal piece 55. Therefore, the current can be promptly cut off and the danger can be avoided.

-Embodiment 2-This is another embodiment in which a thermal protector is used as a protection element. FIG. 3 is a cross-sectional view showing a thermal protector applied to the battery of this embodiment.
The same components as in the first embodiment will be described using the same reference numerals.

Unlike the first embodiment, the contact point 54 has a strip shape, and instead of being welded to the lower plate 51, one end of the contact point 54 is opposite to the fixed end of the bimetal piece 55 and the lower plate 51 and the frame 52.
It is sandwiched between and fixed. Then, both end faces (both ends in the left-right direction in the drawing) are provided between faces where the lower plate 51 and the upper plate 53 face each other.
A support 7 made of an insulating resin in the shape of a hollow rectangular parallelepiped having a through hole is placed therein, and the free end of the contact point 54 and the free end of the bimetal piece 55 enter into the inside of the opening of the support 7 and are in contact therewith.

According to the structure of this thermal protector, since the upper plate 53 is backed by the support 7, the positive electrode contact terminal and the negative electrode contact terminal of the device or charger are respectively connected to the positive electrode terminal surface 22 and the upper plate. Even if it frequently hits 53, the upper plate 53
There is no dent. Therefore, the contact terminal can always be surely applied to the upper plate 53 to be discharged.

-Embodiment 3- This is an example in which a PTC element is used as a protective element instead of the thermal protector of the first embodiment. Since the container 2, the seal 3, the conductive terminal block 4, and the covering material 6 have the same configuration as that of the first embodiment, only the PTC element will be described in detail below with reference to the sectional view of FIG.

The PTC element 15 includes a metal lower plate 151,
A metal upper plate 153 facing the lower plate 151, two plates 1
51 and 153 are composed of a plurality of supporting bodies 17 made of a columnar insulating resin whose both ends are fixed to the opposite surfaces by an adhesive or the like, and a PTC material 155 filled so as to fill the gap between the upper and lower plates 151 and 153. .

Also in the battery in which the PTC element 15 is mounted on the conductive terminal block 4, the conductive terminal block 4 is used as the PTC element 1.
Since it is covered with 5, the electric current during discharging or charging always passes through the PTC material 155. When overcurrent or heat is generated,
The heat inside the container 2 is quickly passed through the conductive terminal block 4 to the PTC.
It is transmitted to the material 155, which causes the resistance value of the PTC material 155 to rise sharply and reduce the amount of current. Also, the battery 1
Is outside the device, only the upper plate 153 is exposed on the negative electrode side, so that the external short-circuit current always passes through the PTC material 155. Therefore, the current amount can be promptly reduced to avoid the danger.

Further, since the upper plate 153 is supported by the support 17, the upper plate 153 does not dent even if the contact terminals of a device or a charger are frequently applied to the upper plate 153. Therefore, the contact terminal can always be reliably applied to the upper plate 153 to be discharged.

-Embodiment 4- This is an example in which a thermal fuse is used as a protective element in place of the thermal protector of Embodiment 1. Since the container 2, the seal 3, the conductive terminal block 4, and the covering material 6 have the same configurations as those of the first embodiment, only the thermal fuse will be described in detail below with reference to the sectional view of FIG.

The thermal fuse 25 includes a lower plate 251 and a frame 25.
2 and an upper plate 253, which have the same shape and quality as the lower plate 51, the frame 52 and the upper plate 53 in the first embodiment. Between the two plates 251, 253, an even number of support bodies 27 made of a columnar insulating resin whose opposite ends are fixed to their opposing surfaces by an adhesive or the like, upper and lower plates 251, 253, and the support body 27 are provided. Columnar fusible alloy 2 formed in the space surrounded by
55 intervenes. The lower end of the fusible alloy 255 is welded to the lower plate 251, and the upper end is welded to the upper plate 253.

Even in the battery in which the thermal fuse 25 is mounted on the conductive terminal block 4, since the conductive terminal block 4 is covered with the thermal fuse 25, the current at the time of discharging or charging is always the fusible alloy 255. pass. At the time of overcurrent or heat generation, the heat inside the container 2 is quickly transferred to the fusible alloy 255 via the conductive terminal block 4, whereby the fusible alloy 255 is melted and cuts off the current. Further, when the battery 1 is outside the device, since the only member exposed on the negative electrode side is the upper plate 253, the external short-circuit current always passes through the fusible alloy 255. Therefore, the current can be promptly cut off and the danger can be avoided.

Further, since the upper plate 253 is supported by the support 27, the upper plate 253 does not dent even if the contact terminals of a device or a charger are frequently applied to the upper plate 253. Therefore, the contact terminal can always be reliably applied to the upper plate 253 to be discharged.

[0030]

As described above, according to the battery with a protective element of the present invention, the substrate on which the protective element is mounted is unnecessary, and thus it is suitable for downsizing. Also, it is safe because the electric current always passes through the protection element.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a battery according to a first embodiment.

FIG. 2 is a cross-sectional view showing a thermal protector applied to the battery of the first embodiment.

FIG. 3 is a cross-sectional view showing a thermal protector applied to the battery of the second embodiment.

FIG. 4 is a cross-sectional view showing a PTC element applied to the battery of Embodiment 3.

FIG. 5 is a cross-sectional view showing a thermal fuse applied to the battery of Embodiment 4.

[Explanation of symbols]

1 battery 2 containers 3 sealant 4 Conductive terminal block 5 Thermal protector 15 PTC element 25 temperature fuse 51, 151, 251 Lower plate (first conductive plate) 53, 153, 253 Upper plate (second conductive plate)

Claims (4)

[Claims] 1. A battery containing a power generating element including positive and negative electrodes, connected to a first electrode of the power generating element, and a second electrode, and a battery with an insulating material on one surface of the battery container. A conductive terminal block provided to seal the container in a liquid-tight manner,
It has two conductive plates and a physical property variable material arranged between the conductive plates, and has a protective element configured to conduct the two conductive plates at all times and to cut off in the event of an abnormality, and the first conductive plate has conductivity. A battery which is connected to a terminal block and has a second conductive plate as a terminal. 2. The battery according to claim 1, wherein the material having variable physical properties is a PTC material, a bimetal material or a fusible material. 3. The battery according to claim 1, wherein an insulating support is provided between the two conductive plates. 4. A protective element having two conductive plates which are normally in conduction with each other via a material having a variable physical property, wherein the conductive plates are interrupted by a change in the physical property of the material having a variable physical property when an abnormality occurs. The protective element is characterized in that an insulating support for fixing the distance between the conductive plates is mechanically provided with a mechanical strength higher than that of the material having variable physical properties.