JP5055824B2 - battery - Google Patents

Description

  The present invention relates to a battery applied to a cylindrical lithium ion secondary battery.

  In recent years, electronic devices such as mobile phones and notebook computers have become cordless and portable, and thin, small, and lightweight portable electronic devices have been developed one after another. In addition, the amount of power used is increasing due to diversification of devices and functions, and there is an increasing demand for higher capacity and lighter batteries as energy sources for these electronic devices.

  Therefore, as a secondary battery that meets this requirement, a lithium ion secondary battery (hereinafter, appropriately referred to as a lithium ion battery) using lithium ion doping / dedoping has been proposed.

Lithium ion batteries include, for example, a positive electrode in which a positive electrode active material layer using a lithium composite oxide such as LiCoO ₂ or LiNiO ₂ is formed on a positive electrode current collector, and can be doped / undoped with lithium, such as graphite or non-graphite A negative electrode active material layer using a carbon-based material such as a carbonizable carbon material has a negative electrode formed on a negative electrode current collector. The positive electrode and the negative electrode are laminated via a separator and bent or wound to form a battery element. This battery element is housed in, for example, a metal can or a laminate film together with a nonaqueous electrolytic solution obtained by dissolving a lithium salt in an aprotic organic solvent to constitute a battery.

  Lithium ion batteries are designed to ensure sufficient safety under normal use conditions. For example, a thermal resistance element (Positive Temperature Coefficient: PTC element) that limits current when the temperature inside the battery rises, a safety valve that disconnects electrical connection inside the battery when the internal voltage rises, and the like are provided.

  Further, since the lithium ion battery is vulnerable to overcharge and overdischarge, the battery pack is usually configured as a battery pack in which a battery cell and a protection circuit are integrated. There are three functions of the protection circuit: overcharge protection, overdischarge protection, and overcurrent protection. These protection functions will be briefly described.

  The overcharge protection function will be described. When a lithium ion battery is charged, the battery voltage continues to rise even after full charge. If this overcharge state occurs, there is a possibility that a dangerous state will occur. Therefore, charging must be performed at a constant current and a constant voltage, and the charging control voltage must be lower than the battery rating (for example, 4.2 V). However, there is a risk of overcharging due to the failure of the charger or the use of a different model charger. When overcharged and the battery voltage exceeds a certain voltage value, the protection circuit turns off the charge control FET (Field Effect Transistor) and cuts off the charging current. This function is an overcharge protection function.

  The overdischarge protection function will be described. When the battery is discharged to a rated discharge end voltage or lower and the battery voltage is in an overdischarged state of, for example, 2 V to 1.5 V or lower, the battery may fail. When discharged and the battery voltage falls below a certain voltage value, the protection circuit turns off the discharge control FET and cuts off the discharge current. This function is an overdischarge function.

  The overcurrent protection function will be described. When the + and-terminals of the battery are short-circuited, a large current flows and there is a risk of abnormal heat generation. When the discharge current flows over a certain current value, the protection circuit turns off the discharge control FET and cuts off the discharge current. This function is an overcurrent protection function. In terms of cutting off the discharge current, the overdischarge protection function and the overcurrent protection function are similar functions.

When the protection circuit described above is configured, an FET is used as a switching element. As the FET, there are an N-channel FET Q _N shown in FIG. 4A and a P-channel FET Q _P shown in FIG. 4B. In the N-channel FET Q _N , when the voltage V _GS between the gate G and the source S is greater than or equal to a positive threshold value, the FET is turned on, and a drain current _ID flows between the drain D and the source S. The P-channel FET Q _P is turned on when the voltage V _GS between the gate G and the source S is equal to or lower than the negative threshold, and the drain current I _{D is connected} between the drain D and the source S.
Flows. Between the drain and the source of the FET, there is a parasitic diode d whose forward direction is opposite to the drain current _ID that flows when the FET is turned on.

A case where an overcharge protection circuit for the lithium ion battery BT is configured using an FET will be described. With N-channel FETs Q _N, as shown in FIG. 4C, a configuration for cutting the power supply line on the negative electrode side of the battery BT during overcharge detection. That is, the drain D of the negative electrode and the FETs Q _N of the battery BT is connected to the source S of the FETs Q _N is connected to the negative output terminal. A charge control signal of a control circuit (configuration of IC (Integrated Circuit)) IC _N is supplied to the gate G of the FET Q _N.

The control circuit IC _N controls the on / off of the FET Q _N to provide overcharge protection. If the battery voltage is in a normal state within the set voltage range, the charging control signal (V _GS ) is set to a positive threshold value or more, the FET Q _N is turned on, and the battery BT is charged from a charger (not shown). I _CH
Is charged by. When than the battery voltage is higher set voltage range, the charge control signal is smaller becomes the positive threshold, FETs Q _N is turned off, charging is prohibited. The discharge to the load is performed via the diode d.

When the P-channel FET Q _P is used, as shown in FIG. 4D, the power supply line on the positive electrode side of the battery BT is disconnected when overcharge is detected. That is, FETQ _P is the secondary battery B
It is arranged on the positive electrode side of T. The source S of the positive electrode and the FETs Q _P of the battery BT is connected, is connected to the drain D of the FETs Q _P is the positive output terminal. The control circuit to the gate G of the FETs Q _P (I
C configuration) IC _P charge control signal is supplied.

In normal state of the battery voltage is within the predetermined voltage range, the charge control signal (V _GS) is the less negative threshold, FETs Q _P is turned on, the charging current from the charger battery BT is not shown _Charged by ICH. When than the battery voltage is higher set voltage range, the charge control signal is larger than a negative threshold, FETs Q _P is turned off, charging is prohibited. The discharge to the load is performed via the diode d.

  Patent Document 1 below describes that a casing material includes an FET and a PTC element that constitute an overdischarge protection circuit for a primary battery.

Special Table 2002-525806

  An example of a conventional cylindrical lithium ion battery to which the present invention can be applied will be described with reference to FIG. The power generation element 10 is housed inside a cylindrical battery container 20.

  In the power generation element 10, a strip-shaped positive electrode 11 and a negative electrode 12 are wound around a center pin 15 via a separator 13, and the separator 13 is impregnated with an electrolyte solution that is a liquid electrolyte. The positive electrode 11 is provided with a positive electrode mixture layer 11b including a positive electrode material capable of doping and dedoping lithium (Li) as a positive electrode active material on both surfaces (or one surface) of a positive electrode current collector 11a made of, for example, aluminum foil. Have a structure. A positive electrode lead 14 made of aluminum or the like is attached to the positive electrode current collector 11 a and led out of the power generation element 10.

  The negative electrode 12 has a structure in which, for example, a negative electrode mixture layer 12b containing a negative electrode material capable of doping and dedoping lithium as a negative electrode active material is provided on both surfaces (or one surface) of a negative electrode current collector 12a made of copper foil. is doing. A negative electrode lead 16 made of copper is attached to the negative electrode current collector 12 a and led out of the power generation element 10.

  The separator 13 is made of, for example, a porous film made of synthetic resin or ceramic. The electrolytic solution includes, for example, a solvent such as an organic solvent and a lithium salt that is an electrolyte salt dissolved in the solvent. A pair of insulating plates 31 and 32 are disposed on the winding peripheral surface of the power generation element 10.

  The battery case 20 is made of, for example, iron (Fe) or stainless steel plated with nickel (Ni), one end surface (negative electrode) side is closed, and the other end surface (positive electrode) side is opened. The battery case 20 is connected to the negative electrode and functions as a negative electrode terminal. Moreover, the safety mechanism 40 and the battery cover 50 are attached to the open end surface portion of the battery container 20 by caulking through the gasket 60, and the inside of the battery container 20 is sealed.

An example of the safety mechanism 40 will be described with reference to FIG. 6 which is a half perspective view. A safety valve 41 made of a metal material such as aluminum and a support holder 42 made of a metal material such as aluminum are fitted via an insulating holder 43. The safety valve 41 has a protrusion 41 a that protrudes toward the power generation element 10 at the center of the bottom, and the protrusion 41 a is inserted into an opening 42 a formed at the center of the bottom of the support holder 42. A flange portion 41b is provided on the outer periphery of the safety valve 41 to ensure electrical connection with the battery lid 50 with the PTC element 44 interposed therebetween. The support holder 42 has openings 42b as a plurality of ventilation holes on the side wall. Is formed. The positive electrode lead 14 is welded to the protruding portion 41 a of the safety valve 41.

  In the safety mechanism 40, when the internal pressure of the battery rises and reaches a predetermined value due to internal short circuit or external heating, the increased internal pressure is transmitted to the safety valve 41 through the opening 42 b of the support holder 42. The safety valve 41 is deformed toward the battery lid 50 by its internal pressure. As a result, the internal pressure of the battery is relaxed, the electrical connection between the safety valve 41 and the positive electrode lead 14 is interrupted, and the electrical connection between the battery lid 50 and the power generation element 10 is interrupted.

  The battery lid 50 functions as a positive electrode terminal of the battery, and is made of, for example, stainless steel plated with nickel similarly to the battery container 20. The battery lid 50 has a flange portion 51 around it and a plurality of notches at the top. The flange 51 of the battery lid 50 is electrically connected to the flange 41 b of the safety valve 41 via the PTC element 44. The resistance value of the PTC element 44 increases as the temperature rises, preventing abnormal heat generation due to a large current.

  The secondary battery mentioned above is manufactured as follows, for example.

  First, a positive electrode material that can be doped and dedoped with lithium, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a mixed solvent to obtain a positive electrode mixture slurry. Next, the positive electrode mixture slurry is applied to the positive electrode current collector 11a, dried, and then compression molded to form the positive electrode mixture layer 11b, whereby the positive electrode 11 is manufactured. Thereafter, the positive electrode lead 14 is connected to the positive electrode current collector 11a by ultrasonic welding or spot welding.

Also, a negative electrode material capable of doping and dedoping lithium and a binder are mixed to prepare a negative electrode mixture, and this negative electrode mixture is dispersed in a mixed solvent to obtain a negative electrode mixture slurry. Next, the negative electrode mixture slurry is applied to the negative electrode current collector 12a, dried, and then compression molded to form the negative electrode mixture layer 12b, whereby the negative electrode 12 is fabricated. Thereafter, the negative electrode lead 16 is connected to the negative electrode current collector 12 a by ultrasonic welding or spot welding.

  And the positive electrode 11 and the negative electrode 12 are wound many times through the separator 13, and a wound electrode body is produced. Thereafter, the wound electrode body is sandwiched between the pair of insulating plates 31 and 32 and accommodated in the battery container 20, the positive electrode lead 14 is welded to the safety valve 41 of the safety mechanism 40, and the negative electrode lead 16 is welded to the battery container 20. To do.

  In addition, an electrolyte solution is prepared by dissolving an electrolyte salt in a solvent. Thereafter, an electrolytic solution is injected into the battery container 20 and impregnated in the separator 13. Subsequently, the safety mechanism 40 and the battery lid 50 are fixed to the open portion of the battery container 20 by caulking through the gasket 60. In this way, a lithium ion battery is completed. Although omitted in the above description, actually, a resin ring washer is attached to the battery lid 50, and the entire battery is covered with a resin tube.

  In a conventional lithium ion battery, since a protection circuit is provided outside the battery cell, it cannot be used alone like a dry battery, and the battery cell and the protection circuit must be packaged in a resin case, There was a problem that the shape became large and the cost increased.

  Furthermore, when a plurality of lithium ion battery cells are connected in series, it is necessary to use an element that can withstand the voltage of the battery connected in series as the FET of the protection circuit. There was a limit. In addition, when a plurality of lithium ion battery cells are connected in parallel, it is necessary to ensure safety in consideration of the fact that current flows from other battery cells when one battery cell is short-circuited. There was a limit to the number of connections. Moreover, when designing a protection circuit for a battery pack composed of a plurality of cells, it is necessary to select a protection element that takes into account the energy of the entire battery pack. There was a problem of increasing the space. The advantage of using a lithium ion battery is that it is lightweight, but as described above, in order to configure it as a battery pack, its advantage depends on the resin case, protection circuit, connection leads between the battery cell and the protection circuit, etc. There was a problem that was not fully demonstrated. For example, when the connection lead is led out from the battery cell, it is necessary to maintain the internal airtightness.

  Patent Document 1 described above describes that an FET element and an overcurrent protection element are arranged in a space on the positive electrode side or the negative electrode side of a cylindrical battery as a measure against overdischarge. However, the empty space on the negative electrode side of the existing cylindrical lithium ion battery is narrow, and it is necessary to widen the empty space on the negative electrode side in order to accommodate both the FET element and the control IC for the protection circuit on the negative electrode side. It becomes. Moreover, in the existing battery, since the positive electrode side is led out from the upper part of the battery container, when the FET element is stored on the negative electrode side, the connection from the positive electrode side (upper part) to the FET element (lower part) There arises a problem that leads, tabs and the like are required. In order to flow charging / discharging current, there is a problem that leads, tabs and the like become relatively large.

  Furthermore, the above Patent Document 1 only describes an example using an FET element and a PTC element, and does not describe how to arrange the control circuit constituting the protection circuit. There is no disclosure of a method for grounding the control circuit.

  Accordingly, an object of the present invention is to eliminate the need to lead out positive and negative leads from the battery cell and connect them to an external protection circuit, and to provide the FET element and control circuit of the protection circuit in a space existing in an existing battery. An object of the present invention is to provide a battery that makes it possible.

In order to solve the above-described problem, the present invention is a cylindrical shape whose one end face is closed, in which a power generation element is housed and made of a metal material connected to the negative electrode side of the power generation element,
A safety valve device disposed on the other end surface side of the container and closing the other end surface of the container;
A battery lid made of a metal material provided so as to be positioned above the safety valve device by a plurality of legs,
The safety valve device has a plate-shaped safety valve made of a metal material that is deformed by an increase in the battery internal pressure, and a blocking portion that blocks electrical connection between the positive electrode side of the power generation element and the battery lid due to deformation of the safety valve. And
A printed wiring board with an opening in the center is interposed between the safety valve and the battery lid,
A P-channel FET for switching a current path between the safety valve and the battery lid on the printed wiring board;
A protection circuit comprising a control circuit for controlling the P-channel FET and having the ground side connected to the container is provided .
In this battery, a P-channel FET and a control circuit are attached to the upper surface of the printed wiring board at the position of the opening between the legs of the battery lid .

  According to the present invention, since a single battery includes a protection circuit, it is easy to connect a plurality of batteries in series or in parallel, and it is unnecessary to connect a protection circuit by pulling out leads to the outside of the battery. Become. In the present invention, the P-channel FET is used to turn on / off the positive line, so that a protection circuit can be arranged in the upper space of the positive safety device, and a long lead is connected for connection. It is unnecessary to provide it. Furthermore, by connecting the ground terminal of the control circuit to a tab obtained by extending a part of the battery container, the wiring pattern can be simplified, and an increase in the number of parts can be prevented. Further, by arranging a printed wiring board instead of the PTC element, there is an advantage that almost no change is added to the configuration of the existing battery.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a main part of one embodiment of the present invention, and FIG. 2 is a plan view of the main part. FIG. 1 is a cross-sectional view taken along the broken line in FIG. In these figures, since the power generation element and the like are the same as those of the conventional cylindrical lithium ion battery described with reference to FIG. 5, only the positive electrode side portion is shown.

  The safety device includes a disk 112 made of a metal material such as aluminum, a plate-like safety valve 114 made of a metal material such as aluminum, and the like. The safety valve 114 has a thin portion so as to function as a cleavage valve. A positive electrode lead 111 attached to the positive electrode current collector is welded to the disk 112. The disk 112 has a protruding portion 113 as a blocking portion formed at the center thereof. The disk 112 has a plurality of openings for ventilation. The protrusion 113 is in contact with or welded to the upper safety valve 114. In addition, the disk 112 and the safety valve 114 are insulated except for the projecting portion 113 by a disk holder which is a ring-shaped insulator (not shown). Further, the safety device is not limited to the configuration shown in FIG. 1, but may be the conventional configuration shown in FIG. 6, or may be another known configuration.

  Conventionally, a PTC element has been disposed between the safety valve 114 and the battery lid 116, but in one embodiment of the present invention, a printed wiring board 115 is disposed. Therefore, the thickness of the printed wiring board 115 is preferably substantially equal to that of the PTC element. The printed wiring board 115 is a ring having an opening in the center, and a wiring pattern can be formed on both sides.

  A pattern that can be electrically connected to the safety valve 114 is formed on the lower surface of the printed wiring board 115. Since a relatively large current flows in this pattern, it is preferable to make a surface contact with the safety valve 114 with a certain large area. For example, a ring-shaped conductive pattern is formed. This conductive pattern is electrically connected to a predetermined position of the conductive pattern formed on the upper surface of the printed wiring board 115 through a through hole or the like.

  The battery case 120 is connected to the negative electrode current collector of the power generation element and functions as a negative electrode terminal. In addition, at the open part of the battery container 120, the flanges of the safety valve 114, the printed wiring board 115, and the battery cover 116 are caulked through the gasket 121, and the battery container 120 is sealed.

  The battery cover 116 integrally includes three legs 117a, 117b, and 117c that rise from the flat flange portion toward the flat terminal surface at the center. These leg portions 117a, 117b, and 117c are positioned at an angular interval of approximately 120 °, and an opening is formed between the leg portions. Although not shown, a resin ring washer is fitted on the battery lid 116, and the entire battery is covered with a resin tube.

  The safety device operates in the same way as a conventional battery has. That is, when gas is generated in the battery container 120 and the internal pressure increases, the safety valve 114 is pushed upward through the opening of the disk 112 to relieve the internal pressure, and the welded portion of the protrusion 113 and the safety valve 114 is separated. Thus, the electrical connection between the positive electrode side of the power generation element and the battery lid 116 is interrupted. Further, when the internal pressure increases, the safety valve 114 itself is broken at its thin portion, and gas is released to the outside through the opening between the central opening 118 of the printed wiring board 115 and the leg portion of the battery lid 116.

  A protection circuit for a lithium ion battery is configured on the printed wiring board 115. That is, a P-channel FET element 131 as a switching element that turns on / off a current path between the positive electrode side (safety valve 114) of the power generation element and the positive electrode output terminal (battery cover 116) of the battery, A control circuit IC 132 for supplying a control signal to the gate, a fuse 133 inserted in series with the above-described current path, and a protection circuit composed of other circuit elements are mounted on the printed wiring board 115. Among the circuit components mounted on the printed wiring board 115, the FET element 131 and the control circuit IC 132, which are relatively large components, have a battery lid so that the upper portion of the components does not contact the battery lid 116. It is made to be located below the opening between the leg portions of 116 (see FIG. 2).

Fuse 133 is for blowing the blown a predetermined value or more current flows, or rises to a predetermined value or higher. One end of the fuse 133 is connected to the FET element 131, and the other end is connected (for example, welded) to the flange portion of the battery lid 116 via a conductive pattern. The conductive pattern including the FET element 131 and the fuse 133 has a size (width or volume) necessary for flowing a charging current and a discharging current.

  Coating material (indicated by a one-dot chain line) 134 that seals the vicinity of the FET element 131 and the fuse 133 as main circuit components mounted on the printed wiring board 115, and a coating material (the one-dot chain line) that seals the vicinity of the control circuit IC 132 135). Note that the entire printed wiring board 115 may be coated.

  A tab 120a formed by protruding a part of the battery container 120 is connected to the conductive pattern connected to the ground-side terminal of the control circuit IC132 by welding or the like. Since the current flowing through the control circuit IC132 is smaller than the charging current or the discharging current, the tab 120a may be small.

FIG. 3 shows a circuit configuration of the protection circuit according to the embodiment of the present invention. Battery positive electrode of (power generating element) BT is connected to the source of the P-channel FETs Q _P 1, is connected to the drains of P-channel FETs Q _P 2 of FETs Q _P 1, the positive source of FETs Q _P 2 via the fuse 133 A side output terminal (battery cover 116) is connected. The FET Q _P 1 is a charge control FET, and a charge control signal S1 is supplied from the control circuit IC 132 to the gate of the FET Q _P 1 via a resistor. FETQ _P 2 is a discharge control FET, and the control circuit IC1 is connected to the gate
A discharge control signal S2 is supplied from 32 via a resistor. A parasitic diode d exists between the drain and source of each FET.

The power supply terminal of the control circuit IC 132 is connected to the positive electrode side of the battery BT and the source of the FET Q _P 2, and the ground terminal (GND) is connected to the negative electrode side of the battery BT. As described above, this connection is made through the tab 120a integrated with the battery container 120.

  In the protection circuit described above, when the voltage of the battery BT becomes an overcharge detection voltage or when the voltage of the battery BT becomes equal to or lower than the overdischarge detection voltage, the control circuit IC132 sends a control signal to the gate of the FET. Prevent overcharge and overdischarge. Here, in the case of a lithium ion battery, the overcharge detection voltage is determined to be 4.2 V ± 0.5 V, for example, and the overdischarge detection voltage is determined to be 2.4 V ± 0.1 V.

When the battery voltage becomes the overcharge detection voltage, the charge control FET Q _P 1 is turned off by the charge control signal S1 from the control circuit IC132, and the charging current is controlled not to flow. Note that after the charge control FET Q _P 1 is turned off, only discharge is possible through the parasitic diode d 1 and the discharge control FET Q _P 2.

When the battery voltage becomes an overdischarge detection voltage, the discharge control FET Q _P 2 is turned off by the discharge control signal S2 from the control circuit IC132, and control is performed so that no discharge current flows. After the discharge control FET Q _P 2 is turned off, the parasitic diode d2 and the charge control FET
Only charging is possible via Q _P 1. Furthermore, when the + and-terminals of the battery are short-circuited, a large current flows and there is a risk of abnormal heat generation. When the discharge current flows over a certain current value, the protection circuit turns off the discharge control FET Q _P 2 and cuts off the discharge current. Further, when an abnormality occurs such that the FET Q _P 1 or Q _P 2 is destroyed and a large current flows, the fuse 133 is blown to ensure safety.

  As described above, in one embodiment of the present invention, since a single battery includes a protection circuit, it is easy to connect a plurality of batteries in series or in parallel, and the lead is drawn out of the battery for protection. It becomes unnecessary to connect a circuit. Since the P-channel FET is used to turn on / off the positive line, it is possible to place a protection circuit in the space above the positive safety device, and there is no need to provide a long lead for connection. And can. Furthermore, by connecting the ground terminal of the control circuit to a tab obtained by extending a part of the battery container, the wiring pattern can be simplified, and an increase in the number of parts can be prevented.

  The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible. For example, when the withstand voltage of the battery is sufficiently high, the overcharge protection function may be omitted. A PTC element may be used instead of the fuse.

It is sectional drawing of the principal part of one Embodiment of this invention. It is a top view of the principal part of one embodiment of this invention. It is a connection diagram which shows the structure of the protection circuit of one Embodiment of this invention. It is a connection diagram used for description of FET which comprises a protection circuit. It is sectional drawing of an example of the conventional cylindrical lithium ion battery which can apply this invention. It is a perspective view of the component of the safety device in the conventional cylindrical lithium ion battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 111 ... Positive electrode lead 112 ... Disk 113 ... Protrusion part 114 ... Safety valve 115 ... Printed wiring board 116 ... Battery cover 117a, 117b, 117c ... Leg part 120 ... Battery Container 120a ... Tab 131 ... FET element 132 ... Control circuit IC
133: Fuse Q _P 1: P-channel FET for charge control
Q _P 2 ... P-channel FET for discharge control

Claims (3)

A container having a cylindrical shape with one end face closed, containing a power generation element, and made of a metal material connected to the negative electrode side of the power generation element;
A safety valve device disposed on the other end surface side of the container and closing the other end surface of the container;
A battery lid made of a metal material provided to be positioned above the safety valve device by a plurality of legs,
The safety valve device includes a plate-shaped safety valve made of a metal material that is deformed by an increase in battery internal pressure, and a shut-off that blocks electrical connection between the positive electrode side of the power generation element and the battery lid by deformation of the safety valve. And
A printed wiring board having an opening in the center is interposed between the safety valve and the battery lid,
On the printed wiring board, a P-channel FET that switches a current path between the safety valve and the battery lid;
A control circuit is provided that controls the P-channel FET and includes a control circuit in which the ground side is connected to the container .
A battery in which the P-channel FET and the control circuit are attached to the upper surface of the printed wiring board at a position of an opening between the leg portions of the battery lid .   The battery according to claim 1, wherein a part of the upper edge of the container is extended to the ground side of the control circuit.   The battery according to claim 1, wherein a fuse that melts at a predetermined current or a predetermined temperature is inserted in series with the current path.

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