JP3498538B2 - Secondary battery and assembled sealing plate for secondary battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery in which a safety device is built in a sealed secondary battery such as a lithium ion secondary battery, and in particular, the electric circuit of the safety device is downsized,
The present invention relates to an assembled sealing plate for a secondary battery, which is mounted and arranged in a sealing portion of a battery and a safety device is incorporated.

[0002]

2. Description of the Related Art Sealed secondary batteries, especially lithium ion secondary batteries, have rapidly increased demand as drive power sources for small portable devices such as video cameras, mobile phones and personal computers due to their high energy density. ing. This lithium ion secondary battery requires a safety device including an electric circuit as a safety circuit for protecting against overcharge, overdischarge and overcurrent. Therefore, it is usually incorporated in a battery-using device as a pack-type battery in which a battery is combined with an electric circuit as a safety circuit.

A pack type battery using a lithium ion secondary battery has a structure as shown in FIG. 1 which is a schematic view, and in FIG. 1, 1 is a cylindrical lithium ion secondary battery 2 or 3 as a device to be supplied. Cases 4 to be mounted in a mountable shape are safety circuits inserted between the lithium ion secondary batteries 2 and 3 and the terminals of the case 1.

The structure of a conventional safety circuit 4 is shown in FIG. 17 as a block diagram, and the positive voltage from the charger is positive terminal 5, PTC element 6, lithium ion secondary battery 3
And 2, FETs 7 and 8, thermal fuse 9, terminal 1
By flowing to the negative side of the charger via 0,
The lithium ion secondary batteries 2 and 3 are charged.

Further, the discharge of the lithium ion secondary batteries 2 and 3 is performed by the PTC element 6, the positive terminal 5, the positive and negative terminals of the device, the negative terminal 10, the thermal fuse 9, and the FE.
Via T8 and 7. The voltage detectors 11 and 12 for monitoring the battery voltage are connected to the control circuit 13, and when the battery voltage becomes higher than a specified value, the FET 8 is turned off to prevent overcharge, and when it becomes lower than the specified value, the FET 7 is turned off. Functions to prevent over-discharge and cuts off the current. F
The voltage detector 14 for detecting the source-drain voltage of the ET7 is connected to the control circuit 13, and when an excessive current is generated between the positive terminal 5 and the negative terminal 10 due to an external short circuit or the like, the FETs 7 and 8 are turned on. Turn off and cut off current. The thermistor 15 is a charger through a terminal 16,
Alternatively, the temperature of the battery is monitored from the side of the device used.

As described above, in the conventional pack type battery,
The function of preventing overcharge of the battery unit, the function of preventing overdischarge, the function of shutting off at the time of excessive current, the function of monitoring the battery temperature, etc. are mounted on the printed circuit board as the safety circuit 4 and configured inside the housing 1. ing.

[0007]

The conventional pack type battery as described above has the following problems.

1) Since the shape and design of the casing 1 are formed so that the battery pack can be easily attached to the supplied device, the casing 1 is a dedicated case corresponding to the supplied device. There are many.

2) Since the housing 1 has a shape and design that can be attached to the supplied device, it is necessary to match the charger with the housing 1, and a dedicated charger corresponding to the supplied device is required. Become.

3) It is necessary to provide a terminal structure having a shape and a design for mounting on a safety circuit or a device to be supplied, and the volume resulting from these is determined by the volume of the lithium ion secondary batteries 2 and 3 to be stored. It will be much larger than

4) It is difficult for general consumers to obtain a single secondary battery such as a lithium ion battery. As described above, the conventional pack type battery has poor versatility.

It is an object of the present invention to provide a secondary battery with a safety device, which incorporates an electric circuit constituting a safety device inside the battery and can handle itself in the same manner as a conventional battery unit. And

Another object of the present invention is to provide a secondary battery provided with a sealing plate that can easily discharge gas to the outside when the valve body breaks due to abnormally high pressure inside the battery. To do.

[0014]

In order to solve the above problems, in the secondary battery of the present invention, the power generation element is capped.
Opening or breaking in the space inside the sealing
A safety circuit board provided with a mechanism is arranged, and the safety circuit board is
The voltage detector and the current interrupt depending on the detection value of the voltage detector.
It is supposed to arrange a safety circuit having a current interruption element for breaking . Then, by placing a microminiaturized safety circuit in a part that does not normally come into direct contact with the electrolytic solution, such as between the cap of the sealing part at the top of the secondary battery and the current cutoff valve, a safety circuit is provided. The secondary battery itself having the built-in battery can be handled in the same manner as a conventional battery alone, and the secondary battery can be easily stored in the battery storage chamber of the device to be supplied.

Further, the present invention is an improvement of the assembled sealing plate which is mounted via a gasket in the opening of the battery case which also accommodates the power generating element and which also serves as a terminal of one polarity. That is, the assembled sealing plate according to the present invention is composed of an inner cap and an outer cap electrically insulated from each other, and a thin metal plate that breaks at a predetermined pressure. One of the caps is electrically connected to the other polarity electrode of the power generating element through the valve body, and both caps have through holes for discharging gas, and Between the caps, there is a hollow portion communicating with the both through holes.

Due to the presence of the hollow portion, a large amount of gas that is generated at one time and breaks the valve body easily moves from the through hole of the inner cap to the through hole of the outer cap and is discharged to the outside.
This eliminates the danger of the battery exploding.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to an upper portion of a unit cell, that is, a positive electrode side, inside a sealing portion formed by a cap, a PTC element, an explosion-proof valve, a current cutoff valve, a gasket for fixing these, , A space that normally does not come into direct contact with the electrolyte, for example between the cap and the current cutoff valve.
A scan part, a basic configuration of the current cut-off device such as a voltage detector and a FET, a control circuit, a capacitor, resistor, is obtained by placing the safety circuit composed of electronic components such as a fuse, thereby, the safety circuit The built-in secondary battery can be handled in the same manner as a conventional battery alone, and can be easily stored in the battery storage chamber of the supplied device.

The safety circuit is made of, for example, epoxy resin,
Water-proof, anti-electrolytic solution-treated, such as poly-butylene-terephthalate resin, that is, coating and sealing treatment, to protect the safety circuit from water invading from the outside and the electrolytic solution of the battery itself. Is.

Further, the safety circuit board is provided with an opening or a part of the safety circuit board is broken by an increase in the internal pressure of the battery. The liquid can be discharged to the outside of the battery from the gas escape hole of the cap through the opening of the safety circuit board, the void, or the breaking mechanism.

In addition, a temperature fuse is arranged in the safety circuit, and the temperature fuse is melted by the heat generation of the current cut-off element such as FET or the battery itself, whereby the positive electrode of the battery and the positive output terminal to the outside are connected. The electrical connection between them can be cut off.

Further, the thermistor is arranged in the safety circuit, and the safety of the battery can be ensured by defining the charging temperature range.

Further, the PTC element is connected to the safety circuit via the PTC element, and the PTC element can be tripped by the heat generation of the current interruption element such as FET.

Further, in place of the ring-shaped PTC element (corresponding to the PTC 21 in FIG. 2), a PTC element is arranged between the positive pole of the safety circuit and the external input / output positive pole, and the battery output is short-circuited. The PTC element can be tripped due to an excessive current due to, the temperature of the battery, or the temperature of the safety circuit.

Further, the cap of the sealing portion has a two-pole structure of a negative electrode for safety circuit and a positive electrode for external input / output, and the negative electrode on the outer peripheral surface or the bottom surface of the battery and the negative electrode for safety circuit are Since the current consumption of the safety circuit is not generated until the device to be supplied or the charger is connected, the battery over-discharge protection function can be eliminated.
The safety circuit, combined with high integration technology of semiconductors, miniaturization technology of parts, and high-density mounting technology for mounting these, normally operates between the cap and the current cutoff valve inside the sealing part at the top of the battery. when it does not directly touch the electrolyte space
It can be miniaturized and placed in the space part.

Further, since a step is provided on the negative electrode for the safety circuit and the positive electrode for external input / output in the cap, it is possible to prevent an external short circuit from occurring during handling of the battery.

Also, the negative electrode for the safety circuit and the positive electrode for external input / output in the cap are bonded with an electrically insulating adhesive, for example, a thermosetting adhesive such as an epoxy type, or electrically insulated. Since it is assembled through the object, the strength of the entire cap can be secured, and the cap's safety circuit negative electrode and external input / output positive electrode can be fixed and insulated well.

Further, the diameter of the gas escape hole on the positive electrode side for external input / output is made larger than the diameter of the gas escape hole on the negative electrode for the safety circuit in the cap. It is possible to make it difficult for an electrical short circuit to occur in the vicinity of.

A preferred secondary battery according to the present invention is
A battery case that also serves as a terminal of one polarity; and an assembled sealing plate attached to the opening of the battery case via a gasket, wherein the assembled sealing plate is connected to the battery in series with a current interruption element and a battery. The printed circuit board includes a safety circuit including a voltage detector that detects a voltage and controls the current cut-off element. This printed circuit board has a through hole for discharging gas, and an outer cap and an inner cap connected to the terminals of the printed circuit board having different polarities are mounted on the printed circuit board.

The assembled sealing plate further includes a valve body made of a thin metal plate disposed inside the battery from the printed circuit board and ruptured at a predetermined pressure, and a terminal portion connected to one cap of the printed circuit board. It includes electrical connection means for electrically connecting through the body to the other polarity electrode of the power generating element. The outer cap and the inner cap each have a through hole for discharging gas, and between the both caps, there is a hollow portion communicating with the both through holes,
Further, the valve body is configured to cut off electrical conduction prior to breaking. Also, the safety circuit is connected to the one polarity terminal through the other cap when the battery is set in the device.

The first feature of this structure is that it has a cavity between the outer cap and the inner cap that communicates with the through holes of both caps. This cavity, as described above,
The inside of the battery has an abnormally high pressure, and the gas that breaks the valve serves to easily transfer from the through hole of the inner cap to the through hole of the outer cap. If the through holes provided in both caps are at the corresponding positions, it is not necessary to provide the above-mentioned hollow portion in particular. In order to make such a structure, it is necessary to align the cap when assembling the cap, which complicates the operation. Also, if the positions of the through holes on both caps match,
There is a possibility that a linear metal member such as a hairpin may enter the through holes of both to electrically connect the caps to each other to short-circuit the battery. According to the present invention, there is no need for special management for matching the through holes when assembling the sealing plate, and the risk of short circuit due to the linear metal member can be reduced.

Further, the outer cap and the inner cap each have the through hole for discharging gas on the side surface, and the cavity is formed inside the bulging portion provided on the side surface of the outer cap. It is preferable. This configuration allows for maximum utilization of space within the inner cap.

The outer cap is preferably provided with a bulging portion on the peripheral edge of its upper surface. The bulging portion can be attached to the terminal portion of the device in a snap hook manner when the battery is set in the device.

Further, in the structure in which the bulging portion is provided on the peripheral portion of the upper surface of the outer cap, the through hole for discharging the gas of the outer cap is preferably provided below the through hole of the inner cap. According to this configuration, for example, a linear metal member such as a hairpin may enter the space between the through hole of the outer cap and the inner cap to electrically connect both caps and short-circuit the battery. Disappears.

The safety circuit built in the printed circuit board has an input of an overcurrent to the battery, an output of an overcurrent from the battery,
Alternatively, it is preferable to have a function of blocking input / output of overcurrent. For example, the voltage detector detects a voltage between the input side and the output side of the current interruption element, and turns off the current interruption element when the detected voltage exceeds a predetermined voltage.

Further, it is preferable that the safety circuit includes a temperature detector, and is configured to turn off the current interruption element when the detected temperature is out of a predetermined temperature range.

Furthermore, the safety circuit preferably includes a thermal fuse connected in series with the battery.

It is preferable that the electrical connecting means further includes a PTC element. The PTC element can be included in a safety circuit incorporated in the printed circuit board instead of being incorporated in the electrical connection means.

Further, the electrical connecting means further preferably includes a sub-filter which is welded to the valve body at the central portion and electrically insulated at the peripheral portion, and the sub-filter is permeable to gas. The welded portion between the sub-filter and the valve body, which has a hole, is configured to function as a current interrupting function means that is released when the gas pressure exceeds a predetermined value.

Further, a safety circuit including an electric current interruption element connected in series to a battery instead of the printed circuit board and a voltage detector for detecting the voltage of the battery and controlling the electric current interruption element is formed like an IC. A package corresponding to the terminal portion of the printed circuit board may be provided by integrally molding it into a package, and a package having a space between the terminals may be arranged.

According to the present invention, a space for incorporating a safety circuit for a battery can be secured in the inner cap of the assembly sealing plate, so that only in a specific battery-using device in which the safety circuit is combined with the outside of the battery as in the conventional case. It is not necessary to use a compatible battery pack, and an independent battery with a built-in safety circuit can be provided.

[0041]

Embodiments of the present invention will be described below with reference to FIGS. 4 to 16.

(Example 1) FIG. 2 is a sectional view of a sealing portion of a conventional cylindrical lithium ion secondary battery, and FIG. 3 (a) is an exploded perspective view of the conventional sealing portion.
FIG. 3B shows an exploded sectional view of the conventional sealing portion. This sealing part has a PTC element which is a current reduction function means when the battery heats up, a current cutoff valve which is a current cutoff function means when the battery internal pressure rises, and an explosion proof valve which is an explosion protection function means when the battery internal pressure further rises. The filter 17, the sub-filter 18, the inner gasket 19, the valve body 20, the PTC element 21, the cap 22, the sealing plate ring 23, and the gasket 24 are included. Normally, the current from the positive electrode is
It is connected to a filter 17 having a through hole C via a lead plate 25, then comes into surface contact with this and communicates with a sub filter 18 having a through hole B. Further, since the central portion of the sub-filter 18 and the valve body 20 are joined by welding, the positive electrode current passes through the valve body 20 and the ring-shaped PTC element 21 which is in surface contact with the valve body 20 and the through hole D. Is guided to the cap 22 having.

The cap 22, the PTC element 21, and the valve body 20 are integrated by a ring-shaped inner gasket 19, and since the inner gasket 19 is formed by molding an insulator such as polycarbonate, the sub-filter 18 The electrical connection between the valve body 20 and the valve body 20 is limited to only the welded portion. The peripheral edge of the filter 17 has a structure in which the peripheral edges of the sub-filter 18 and the inner gasket 19 are crimped, and after the crimping is completed, the filter 17 is integrated as an assembly forming a sealing portion. The gasket 24 is formed by molding an insulator such as polycarbonate into a ring shape. When the assembly of the above-mentioned sealing portion is incorporated into the battery case 26 and caulking and sealing, the battery case 26 and the filter 17 are insulated from each other. There is.

The valve body 20 is provided with a slit A as an explosion proof valve which is an explosion proof function means, and is provided in the through hole C of the filter 17 and the sub filter 18 when a gasified electrolytic solution is generated. After passing through the through hole B, the valve body 20
Is pushed up to the side of the cap 22.

Next, the current reduction function means by the PTC element 21 will be described. The PTC element 21 is an element whose resistance value sharply rises at a specified temperature, and the temperature of the battery rises due to overcharge or a large discharge current, for example, a current value equal to or more than a current value corresponding to 1 hour discharge, and reaches the specified temperature. Then, by increasing the resistance value and reducing the current,
It prevents the battery from becoming thermally unsafe.

The means for interrupting current when the internal pressure of the battery rises by welding the sub-filter 18 and the valve body 20 will be described. Electrolyte gasified by heat generation,
The valve body 20 is pushed up to the cap 22 side through the through hole C of the filter 17 and the through hole B provided in the sub filter 18. At this time, when the pressure of the gas exceeds the welding force between the sub-filter 18 and the valve body 20, the welding is released, so that the electrical connection is cut off and the function as a current cutoff valve is performed.

Furthermore, the explosion-proof function means by the valve body 20 will be described. After the current interruption function means by the sub-filter 18 and the valve body 20 is activated, the electrolytic solution gasified by heat generation further pushes the valve body 20 toward the cap 22 side. On the other hand, since the periphery of the valve body 20 is fixed by the inner gasket 19, the filter 17, the gasket 24, and the battery case 26, the valve body 20 is affected by the gas pressure.
The slit A provided in the is broken, and at that time, the gasified electrolytic solution escapes to the cap 22 side. As a result, the gasified electrolytic solution is discharged from the through hole D of the cap 22 and its pressure is reduced to prevent the battery itself from exploding.

In the present invention, the space inside the sealing portion is
The safety circuit shown in FIG. In FIG. 4, + is a positive pole for inputting / outputting to the outside of the secondary battery 28 controlled by the safety circuit 27, S is a negative pole of the safety circuit 27, and the secondary battery 28 is on the side of the device to be supplied or the charger. Connect to the negative pole formed on the outer peripheral surface or the bottom surface. The symbol − is a negative electrode formed on the outer peripheral surface or the bottom surface of the secondary battery 28.

The positive output of the secondary battery 28 is passed through the current cutoff function means 29 and the PTC element 30 (corresponding to the PTC element 21 in FIG. 2) constituted by the sub-filter 18 and the valve body 20 described in FIG. Connected to the safety circuit 27.

When the S terminal is connected to the negative electrode of the secondary battery 28 on the side of the device to be supplied or the charger,
When the voltage between the output side of the PTC element 30 and the S terminal is within the specified value, the voltage detector 31 built in the sealing portion is
The current cut-off element 32 such as ET is turned on to enable charging from the charger. On the other hand, when the voltage between the output side of the PTC element 30 and the S terminal becomes higher than the specified value, the voltage detector 3
1 turns off the current interruption element 32 such as FET to protect the secondary battery 28 from overcharging.

The safety circuit 27 performs the above operation. However, when an FET is used as the current cut-off element 32, even if the FET is in the off state, due to its body diode effect, +
The secondary battery 28 can be discharged through the electrodes. The capacitor 33 serves to prevent static electricity between the positive and negative electrodes and prevent malfunction due to noise.

FIG. 5 shows a modification of the safety circuit 27 shown in FIG. 4, in which a thermistor 34 is added and a voltage detector 35 having a function of monitoring a change in resistance value due to the temperature of the thermistor 34 is added. As a result, when the temperature of the secondary battery 28 goes out of the specified range (0 ° C to 60 ° C or less), the FET
The effect of turning off the current cut-off element 32 is added.

Further, FIG. 6 shows another modified example of the safety circuit 27 shown in FIG. 4, in which the conventional ring-shaped PTC element (corresponding to the PTC element 21 in FIG. 2) is abolished and the safety circuit is added. PT between the terminal and the positive pole for external input / output
The C element 36 is inserted.

In the above description, the negative voltage applied to the negative pole S of the safety circuit 27 is obtained from the negative of the battery case through the wire connection of the supplied device to which the battery is attached or the charger. It is also possible to connect the negative voltage for the safety circuit 27 directly to the battery case. However, in this case, the self-discharge loss due to the current consumption of the safety circuit 27 when the battery is not used becomes a problem.
Measures for long-term storage are required.

[0055] (Example 2) safety circuit 27 of the rechargeable battery 28 sealing portion of the internal structure shown in FIG. 4
The case of being incorporated in a space will be described with reference to FIGS. 7 and 8. FIG. 7 is a sectional view of the sealing portion, FIG. 8A is an exploded perspective view of the sealing portion, and FIG. 8B is an exploded sectional view of the sealing portion. The structure extending to the safety circuit negative electrode 37 is different.

In FIGS. 7 and 8, the PTC element 21
The electrode is in surface contact with a flexible wiring board 38 made of a polyimide material, and is connected to the safety circuit 27 through a through hole or wiring. In addition, E is a through hole for the explosion-proof structure provided in the flexible wiring board 38, and corresponds to the opening of the safety circuit board described above. Therefore, a portion that is easily broken may be provided. On the other hand, the negative electrode 37 for the safety circuit makes surface contact with the flexible wiring board 38,
It is connected to the safety circuit 27 through wiring. The input / output terminal + of the secondary battery 28 controlled by the safety circuit 27 is
Through the flexible wiring board 38, the positive electrode 39 for controlled input / output of the secondary battery is formed by surface contact. In addition, F is a waterproof and electrolytic solution resistant coating of the safety circuit 27, 41, 4
2 is a thermosetting adhesive such as an epoxy type, 40 and 45 are insulators such as ABS resin for insulating between the negative electrode 37 for the safety circuit and the controlled positive / negative electrode 39 of the secondary battery, 44
Is a sealing plate ring.

(Embodiment 3) As shown in FIG. 6, when the PTC element 36 is arranged between the positive pole of the safety circuit and the positive pole for external input / output, as shown in FIG. Controlled input / output positive pole 39
The a itself can be composed of a PTC element. The configuration of the other parts is the same as in FIGS. 7 and 8.

Fourth Embodiment As shown in FIG. 10, the connection between the controlled positive input / output positive electrode 39 of the secondary battery and the flexible wiring board 38 is as shown in FIG. The pole 39 may be connected to a component on the flexible wiring board 38 by a spring material 46 such as phosphor bronze. In this case, the configuration of the battery cap can be simplified, and
The lower side of the flexible wiring board 38 is brought into surface contact with the valve body 20 via the facing PTC element 21, and the upper side of the flexible wiring board 38 is brought into surface contact with the facing negative electrode 37 for the safety circuit. The whole part can be easily constructed. In addition, 41 and 49 are thermosetting adhesives such as epoxy type.

The safety circuit 27 described above can have an IC package specification as shown in FIG. In FIG. 11, 50 is a VDD (GND) lead, 51 is a VIN (VSS) lead, and 52 is a VOUT lead. Each lead 50, 51, 52 can be arranged in place of the printed circuit board 38 in FIG. , PBT except the portion G that contacts the negative electrode 37 for the safety circuit, the PTC element 21, and the positive electrode 39 for controlled input / output of the secondary battery.
Since an insulating coating is applied with an electrolyte resistant material such as (polybutylene terephthalate), a printed circuit board is not required, and the assembly is easy when assembling the sealing portion. The spaces of the leads 50, 51, 52 correspond to the above-mentioned voids and serve as passages for the gasified electrolytic solution to be released.

Further, as shown in FIG. 12, the safety circuit negative electrode 37 in FIG. 7 has a plurality of gas escape holes H for the explosion-proof structure and the controlled input / output positive electrode 3 of the secondary battery.
9 must have a through hole I for mechanically contacting the surface of the safety circuit negative electrode 37. In this case, the controlled input / output positive electrode 39 of the secondary battery is as shown in FIG. In addition, a plurality of gas escape holes J larger than the plurality of gas escape holes H of the safety circuit negative electrode 37 and a safety circuit connected to the controlled battery positive / negative electrode 39 of the secondary battery via the safety circuit negative electrode 37. A thermosetting adhesive such as an epoxy-based adhesive is applied to a range K that does not cover the through hole I for mechanically contacting the surface of the negative electrode 37 for use. Negative pole 37 for safety circuit and positive pole 3 for controlled input / output of secondary battery
9 can also be formed integrally by applying a thermosetting adhesive such as an epoxy to a metal material such as a nickel material that has been drilled in advance.

(Embodiment 5) FIG. 14 is a vertical cross-sectional view of a main part of a lithium ion secondary battery provided with an assembled sealing plate of this embodiment. The assembly sealing plate 60 shown here includes an inner cap 61, an outer cap 65, and a printed circuit board 70 to which an element 72 is attached.

The assembly sealing plate further includes a printed circuit board 70.
A ring-shaped PCT element 73 arranged on the lower surface of the valve, a valve body 74 made of a thin metal plate, a sub-filter 75 having a through hole 76 for welding the central portion of the valve body 74 welded to the central portion, and gas. Filter 7 having through holes 78 for passing
7 and an inner gasket 79. The inner gasket 79 covers the portion extending from the peripheral portion of the outer cap 65 to the peripheral portion of the valve element 74, thereby preventing electrical contact between the valve element 74 and the peripheral portion of the sub filter 75. Also, the filter 77 is
By sandwiching the peripheral portions of the sub-filter 75 and the inner gasket 79 between the peripheral portions, the whole is assembled as an integrated sealing plate. The inner gasket 79 is provided on the peripheral portion of the upper surface of the filter 77 to allow the outer cap 6
5, printed circuit board 70, PTC element 73, and valve body 7
Electrical contact with the peripheral portion of 4 is blocked.

Next, the printed circuit board 70 will be described in detail. The printed circuit board 70 is a flexible insulating plate on which wiring is provided. The printed circuit board 70 fixes an element 72 in which an electric circuit constituting a safety circuit, which will be described later, is packaged to the center, and an inner cap 61 and an inner cap 61 so as to cover the element 72. The outer cap 65 is fixed by an electrically insulating adhesive 68, such as an epoxy resin. The printed circuit board 70 has a plurality of through holes 71 for passing gas.

The inner cap 61 has four through holes 62 for passing gas therethrough, and has an insulating coating 63 on its outer surface for electrically insulating it from the outer cap 65. Further, the outer cap 65 is provided with a bulging portion 96 that bulges outward in order to form a cavity 95 that allows gas to pass between the outer cap 65 and the inner cap 61. Four holes 66 are provided. Furthermore, the inner cap 6
An adhesive 69 is interposed between the outer cap 65 and the outer cap 65 to insulate the outer cap 1 and the outer cap 65 from each other. The flange portion 64 of the inner cap 61 is connected to the negative terminal of the printed circuit board 70 to which the element 72 is connected, and the flange portion 67 of the outer cap 65 and the PCT element 73 are connected to the positive terminal. Wiring is applied.

The assembled sealing plate 60 constructed as described above
Is attached to the opening of the battery case 90. An electrode plate group 91 in which a positive electrode plate and a negative electrode plate are spirally wound via a separator is inserted in the battery case 90. After welding one electrode of the electrode plate group, for example, the positive lead plate 93 to the filter 77 of the assembly sealing plate 60, the gasket 94 is attached to the peripheral edge of the assembly sealing plate 60, and the upper end of the case 90 is attached to this gasket part. By caulking, the battery case 90 is liquid-tightly and airtightly sealed. In addition, 92 has shown the insulating plate. The negative electrode lead plate (not shown) of the electrode plate group 91 is welded to the bottom surface of the battery case. Therefore,
The battery case 90 also serves as the negative electrode terminal of the battery.

When the assembled sealing plate 60 is mounted on the battery case 90 as described above, the outer cap 65 is provided with the printed board 70, the PTC element 73 in contact with the printed board 70, and the element 73.
Is connected to the positive electrode of the electrode plate group 91 via the valve body 74 in contact with the valve body 74, the sub-filter 75 joined to the valve body 74 at the central portion, and the filter 77, and functions as a positive electrode terminal.

Next, the safety device shown in FIG. 16 will be described. In FIG. 16, reference numeral 100 denotes a secondary battery to which the assembled sealing plate 60 is attached. Reference numeral 101 denotes a switch that functions as a current cutoff function unit that is composed of a joint portion between the valve element 74 and the sub filter 75 connected to the positive electrode lead of the battery. This switch 101 has the P
The TC element 73 is connected in series. In the element 72 in which the electric circuit is packaged, the temperature fuse 106 and the current interrupt element 10 connected in series with the PTC element 73 are provided.
3. A voltage detector 102 that detects a voltage and controls the current cut-off element 103, a thermistor 107, and a capacitor 104 are incorporated.

The positive terminal of the element 72 is connected to the outer cap 65. On the other hand, the negative terminal S
It is connected to the inner cap 61, which is connected to the negative terminal of the battery via the switch 105. Therefore,
When this battery is set in a device that uses batteries, the negative terminal on the device connected to the battery case, which is the negative terminal of the battery,
It is electrically connected to the inner cap 61. That is, the switch 105 is turned on by setting the battery in the device.

As described above, when the battery with the assembled sealing plate 60 is set in the device and the switch 105 is turned on, a predetermined voltage is applied between the output side of the PTC element 73 and the S terminal. Then, the voltage detector 102 is connected to the current interruption element 10
Turn on 3 to allow acceptance of charging current from the charger. Further, when the voltage of the battery 100 appearing in the voltage between the output side of the PTC element 73 and the S terminal becomes higher than the specified value, the voltage detector 102 turns off the current interruption element 103 to protect the battery 100 from overcharge current. To do.

The safety circuit incorporated in the element 72 will be described in more detail. The voltage detector 102 detects the voltage of the battery 100 and the voltage of the current interruption element 103 to control the current interruption element. When the voltage of the battery 100 detected by the voltage detector 102 is higher than the predetermined upper limit set voltage, overcharge occurs, and the voltage of the battery 100 detected by the voltage detector 102 is lower than the predetermined lower limit set voltage. Sometimes it is over-discharge. The voltage detector 102 turns off the current interruption element 103 when the detected battery voltage exceeds a predetermined upper limit voltage or falls below a predetermined lower limit voltage,
Cut off the current. Further, the voltage detector 102 is, for example, a current interrupt element 1 including a field effect transistor (FET).
The voltage between the input side and the output side of 03 is detected, and when it becomes higher than a predetermined set voltage, for example, it is detected that an excessive current has flown due to a short circuit or the like, and the current cut-off element 103 is turned off. Further, the voltage detector 102 detects the voltage of the thermistor 107, and the temperatures of the battery 100 and the current cutoff element 103 are within a specified range, for example, the battery temperature is 0 ° C. to 60 ° C.
When the temperature is out of the range of ° C, the current cutoff element 103 is turned off. The temperature fuse 106 functions as a safety device that is cut off due to abnormal heat generation of the battery 100 and the current cutoff element 103.

The safety circuit incorporated in the element 72 functions as described above. FET as the current interruption element 103
, Even when it is off, due to its body diode effect, through the positive pole the battery 100
Can be discharged. The capacitor 104 is provided as a countermeasure against static electricity between the positive pole and the negative pole, and prevents malfunction due to noise. The resistance value of the PTC element 73 rapidly increases when the temperature reaches the specified temperature. When the temperature of the battery rises due to the flow of an overcharge current or a large discharge current, for example, a current value equal to or more than the current value corresponding to 1-hour rate discharge, and the PTC element 73 reaches the specified temperature
The resistance value sharply increases and the current is reduced. This prevents the battery from becoming thermally unsafe. The PTC element 73 can also be incorporated in the element 72.

Next, the function of the assembly sealing plate when the internal pressure of the battery rises will be described. Despite the functions of the safety circuit and the PTC element as described above, when the temperature inside the battery becomes high and the electrolytic solution containing mainly the organic solvent is gasified, the gas passes through the holes 78 of the filter 77 and the holes 76 of the sub-filter 75. The valve element 74 is pushed up to the printed circuit board side through. When the gas pressure exceeds the welding force between the sub-filter 75 and the valve element 74, the welded portion is removed and the sub-filter 7
5 and the valve element 74 are electrically disconnected. This disconnects the electrical connection between the battery and its charging and / or discharging circuit. In this way, the sub-filter 75 and the valve element 74 work as a switch having a current cutoff function, that is, a current cutoff function means.

Next, when the gas pressure further increases, the valve element 74 is further pressed toward the printed circuit board. And
When the gas pressure exceeds a certain value, the valve element 74 breaks from a notch (not shown) provided on a part of its surface. Therefore, the gas passes from the broken portion through the through hole 71 of the printed circuit board, and further through the through hole 62 of the inner cap 61, the cavity 95 between the inner cap 61 and the outer cap 65, and the through hole 66 of the outer cap 65. Is released to the outside via

At this time, since the hollow portion 95 is provided between the inner cap 61 and the outer cap 65, even if the positions of the through holes 62 and 66 of both caps do not coincide with each other, they pass through the through hole 62. The generated gas easily reaches the through hole 66 through the cavity 95 and is discharged to the outside. Without the cavity 95, a large amount of gas generated at one time cannot pass through the narrow gap between the caps at the positions where the through holes 62 and 66 of both caps are not aligned, and the inside of the battery is overheated. This will cause pressure and risk of bursting.

In this way, when the electrolytic solution is gasified due to the high temperature of the battery and the pressure inside the battery rises abnormally,
When the current is cut off by the current cut-off function means between the sub-filter 75 and the valve element 74, and the pressure is further increased, the valve element 74 is broken as an explosion-proof function means, and the caps 61 and 65 are provided.
It is released to the outside through the through hole. Therefore, there is no danger of the battery itself bursting.

(Embodiment 6) FIG. 15 is a longitudinal sectional view of a main part of an assembled sealing plate according to this embodiment. The assembled sealing plate 80 is essentially the same as the assembled sealing plate 60 of the fifth embodiment except that the structures of the inner cap 81 and the outer cap 85 are changed. Inner cap 81
So that the collar portion 84 contacts the minus terminal of the printed circuit board 70, and the outer cap 85 is attached to the collar portion 8 of the printed circuit board 70.
7 is adhered to the printed circuit board 70 by an adhesive agent 88 so that the positive terminal 7 contacts the positive terminal of the printed circuit board 70. The inner cap 81 has a through hole 82 for passing gas.
On the side surface.

On the other hand, the outer cap 85 has a through hole 86 for passing gas therethrough at the lower side surface. The outer cap 85 has a hollow portion 97 provided between the outer cap 85 and the inner cap 81 by bulging the upper peripheral portion outward. The bulging portion 98 can be attached to the terminal portion of the device in a snap hook manner when the battery is set in the device. The provision of the insulating film 83 on the outer surface of the inner cap and the provision of the insulating material 89 between both caps are exactly the same as in the fifth embodiment.

Also in this structure, the gas that breaks the valve element 74 and enters the through hole 82 of the inner cap 81 does not have the cavity 9
7 is easily discharged through the through hole 86 of the outer cap 85 to the outside. Further, since the through hole 86 for discharging the gas of the outer cap 85 is lower than the through hole 82 of the inner cap 81, a linear metal member such as a hairpin is connected from the through hole of the outer cap to the inner cap. There is no possibility of short-circuiting the battery by entering the space between them and electrically connecting both caps.

In the above embodiment, the inner cap and the outer cap each have four through holes for venting gas, but the number of through holes should be appropriately selected according to the size and the battery. Is.

Although the positive electrode of the battery is electrically connected to the outer cap, the positive electrode of the battery may be connected to the inner cap.

Although the PTC element is inserted between the printed circuit board and the valve body as one component, it may be incorporated in the element 72 on the printed circuit board.

Further, the materials and the like shown in each of the above embodiments are examples, and can be used by being modified within the range of fulfilling the function.

Furthermore, in the above embodiment, an example in which the present invention is applied to a lithium ion secondary battery has been described.
It goes without saying that the present invention can be applied to other secondary batteries as well.

[0084]

As described above, according to the present invention, a situation in which the gas pressure inside the secondary battery is abnormally increased is controlled by controlling so as not to overcharge or overdischarge by itself. When the gas pressure in the battery becomes abnormally high, it is possible to obtain a secondary battery in which gas is promptly released to prevent the battery from exploding.

By carrying out the present invention in the form as described above, the following problems, which have been problems in the conventional pack type battery, can be solved.

1) The pack type battery has a shape and design that can be attached to the supplied device, so that it becomes a dedicated pack for the supplied device.

2) Since the battery pack is shaped and designed so that it can be attached to the device to be supplied, the charger is also adapted to the pack type battery, or a dedicated charger including the storage part of the device to be supplied. It becomes.

3) The volume of the pack type battery provided with the shape and design for mounting on the safety circuit and the device to be supplied and the terminal structure must be larger than the volume of the battery accommodated in the pack type battery.

4) General consumers cannot obtain a single secondary battery such as a lithium ion battery. Furthermore, if the size of the rechargeable battery such as lithium ion is specified in advance, it is possible to produce and supply the rechargeable battery satisfactorily regardless of the shape, design, release time, and release amount of each supplied device. At the same time, even for general consumers, by purchasing the device to which the above-mentioned battery is applied, it is possible to obtain the advantageous effect that the required amount of the secondary battery can be easily obtained when needed. .

[Brief description of drawings]

FIG. 1 is a schematic diagram of a pack type lithium ion secondary battery.

FIG. 2 is a sectional view of a sealing portion of a conventional cylindrical lithium ion secondary battery.

FIG. 3A is an exploded perspective view of the sealing portion. (B) Exploded sectional view of the sealing part

FIG. 4 is a block diagram of a safety circuit according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing a modification of the safety circuit.

FIG. 6 is a block diagram showing another modification of the safety circuit.

7 is a cross-sectional view of the sealing portion in the second embodiment incorporating the safety circuit shown in FIG.

FIG. 8A is an exploded perspective view of the sealing portion. (B) Exploded sectional view of the sealing part

FIG. 9 is a sectional view of a sealing portion according to a third embodiment.

FIG. 10 is a cross-sectional view of the sealing portion according to the fourth embodiment.

11A is a front view of a safety circuit having a package specification, FIG. 11B is a side view of the safety circuit, and FIG. 11C is an exploded perspective view of the safety circuit.

FIG. 12 (a) is a front view of a negative electrode for a safety circuit. (B) sectional view taken along the line II '

FIG. 13A is a plan view of a controlled input / output plus electrode of a secondary battery, and FIG.

FIG. 14 is a vertical cross-sectional view of a main part of a lithium-ion secondary battery including an assembled sealing plate according to a fifth embodiment.

FIG. 15 is a vertical cross-sectional view of the main parts of the assembled sealing plate according to the sixth embodiment.

FIG. 16 shows an electrical circuit including a safety device incorporated within a battery.

FIG. 17 is a block diagram of a conventional safety circuit in a pack-type lithium-ion secondary battery.

[Explanation of symbols]

17 filters 18 sub filters 19 Inner gasket 20 valve body 21 PTC element 22 Cap 27 Safety circuit 28 Secondary battery 32 Current interrupt element 34 Thermistor 37 Negative pole for safety circuit 38 Flexible wiring board 39, 39a Controlled input / output positive pole 41, 42, 49 Thermosetting adhesive 60, 80 Assembly sealing plate 61, 81 inner cap 62, 82 through hole 63, 83 Insulating film 64, 84 collar part 65, 85 outer cap 66,86 through hole 67, 87 Tsubabe 68, 69, 88, 89 Adhesive 70 Printed circuit board 71 through hole 72 elements 73 PTC element 74 Disc 75 sub filter 76 through hole 77 Filter 78 through hole 79 Inner gasket 90 battery case 91 plate group 92 Insulation plate 93 Positive electrode lead plate 94 gasket 95, 97 cavity 96, 98 bulge 100 batteries 101 switch 102 voltage detector 103 Current interruption element 104 capacitor 105 switch 106 Thermal fuse 107 Thermistor A slit B, C, D, E, H, J through holes

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-201358 (JP, A) JP-A-7-272748 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01M 2/34 H01M 10/42-10/48

Claims (7)

(57) [Claims] 1. A safety device provided with an opening or a breaking mechanism in a space inside a sealing portion for sealing a power generating element with a cap.
A secondary battery in which all circuit boards are arranged, and a safety circuit having a voltage detector and a current interruption element for interrupting a current according to a detection value of the voltage detector is arranged on the safety circuit board . 2. The secondary battery according to claim 1, wherein the positive output of the power generating element is connected to a safety circuit via a PTC element. 3. The secondary battery according to claim 1, wherein a PTC element is arranged between the positive electrode of the safety circuit and the positive electrode for external input / output. 4. The secondary battery according to claim 1, wherein the cap of the sealing portion has a two-pole structure of a negative electrode for safety circuit and a positive electrode for external input / output. 5. A battery case for accommodating a power generating element and also serving as a terminal of one polarity thereof, and an assembly sealing plate mounted on an opening of the battery case via a gasket, wherein the assembly sealing plate is mutually Includes a valve body having an electrically insulated inner cap and an outer cap, and a thin metal plate that breaks at a predetermined pressure, and having a current cut-off function means that cuts off electrical conduction prior to breaking, one of the caps It is electrically connected to the other polarity electrode of the power generation element through the valve body, both caps have through holes for discharging gas, and the both caps communicate with the above through holes. The secondary battery according to claim 1, wherein the secondary battery has a hollow portion. 6. A battery case which accommodates a power-generating element and also serves as a terminal of one polarity thereof, and an assembly sealing plate attached to an opening of the battery case through an electrically insulating gasket, wherein the assembly sealing is provided. The plate incorporates a safety circuit including a current interrupting device connected in series to the battery and a voltage detector for detecting the voltage of the battery and controlling the current interrupting device, and a through hole or breaking mechanism for discharging gas. A printed circuit board, an outer cap and an inner cap connected to and attached to terminals of different polarities of the printed circuit board on the printed circuit board, a metal thin plate disposed inside the battery from the printed circuit board and breaking at a predetermined pressure Is connected to one of the caps of the printed circuit board, which has a current interrupting function means for interrupting electrical conduction prior to breakage. Electrical connection means for electrically connecting the terminal part to the other polarity electrode of the power generating element through the valve body, both caps having through holes for discharging gas, and both caps. In between, there is a cavity communicating with the both through holes, and the safety circuit is connected to the one polarity terminal through the other cap when the battery is set in the device. Rechargeable battery. 7. A valve body comprising an inner cap and an outer cap electrically insulated from each other, a thin metal plate that is broken at a predetermined pressure, and a current cutoff function means for cutting off electrical continuity prior to breaking, and Safety having means for electrically connecting one of the caps through the valve body to the one-polarity electrode of the power generation element, a voltage detector, and a current interruption element for interrupting the current according to the detection value of the voltage detector An assembling seal for a secondary battery, comprising a circuit, wherein both caps have through holes for discharging gas, respectively, and between the both caps, there is a cavity communicating with the through holes. Board.