JP2010212192A - Lithium ion battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion battery pack which detects expansion and abnormal temperature by a few man-hours and members and by a detecting member of a simple structure. <P>SOLUTION: An abnormality detecting means 5 which has a temperature detection function and uses a conductor that fractures when a packaging member expands is installed so as to go along the surface of the central part of battery pack in a battery pack using packed batteries 110 laminating lithium ion batteries. The output of the abnormality detecting means 5 is connected to an abnormality detecting circuit 9 in a protection circuit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lithium ion battery pack using an assembled battery in which lithium ion batteries using a laminate film as a packaging member are connected in series and / or in parallel.

  A lithium ion battery is a typical secondary battery having a high energy density, and is known to be used as a power source for driving portable devices such as a mobile phone, a notebook computer, and a video camera.

  In the lithium ion battery, a lithium compound is used as a positive electrode active material, a carbon-based material is used as a negative electrode active material, and an organic solvent in which a lithium salt is dissolved is used as an electrolytic solution. When this organic electrolyte reaches a voltage range significantly exceeding 4.2 V, gas is generated by oxidative decomposition, and the battery internal pressure rises, and the battery element swells and the battery element generates heat to generate lithium ions. Battery deterioration may be accelerated.

  To prevent this, the lithium-ion battery pack is equipped with a protection circuit board, and overcharge, overdischarge, temperature, etc. are monitored and abnormalities are detected by internal components such as the protection circuit board including the charge / discharge protection circuit. In such a case, it has a function of shutting off energization between the lithium ion battery pack and the external device.

  Here, since the lithium ion battery is formed by laminating the positive electrode sheet and the negative electrode sheet, the lithium ion battery can be reduced in thickness. It can handle large capacity specifications such as trains and uninterruptible power supplies. Further, when using a plurality of batteries, it is more advantageous for weight reduction to use a laminate film that is a lighter material than the metal case.

  However, the lithium-ion battery using a laminate film outer package has a noticeable tendency to swell when a gas is generated as compared to a metal case. When the battery falls into an overcharged state, the electrolyte is oxidized. In some cases, cracked gas is generated, and the battery internal pressure rises to cause the battery to swell.

  Therefore, in Patent Document 1, two or more conductors serving as swelling detection means are provided on the outer surface of the battery outer member for one battery in which a part of the electrode terminal is exposed and the battery element is sealed with the packaging member. A battery pack has been proposed that includes a means for detecting battery swelling by fixing the battery and the conductor breaking when the battery is swollen.

  Further, for example, in Patent Document 2, in a battery pack having a rectangular metal case and a protective circuit board, the battery is formed by bringing a thermal conductive sheet into close contact between the protective circuit board and the battery when the battery falls to a high temperature. There has been proposed a battery pack having a function of sensing the temperature of an element and shutting off the power supply between the battery pack and an external device by an internal component of the protection circuit board when the temperature is abnormal.

  Furthermore, in patent document 3, the temperature detection part and the pressure detection part which fractures | ruptures at the time of expansion | swelling were united with the secondary battery apparatus which connected the lithium ion battery which used the square metal case for the exterior in series, and parallel connection. There has been proposed a secondary battery device provided with means for detecting a temperature rise and expansion of a battery by installing a sensor in each unit battery.

JP 2008-192432 A JP 2007-124775 A JP-A-11-162527

  However, in Patent Documents 1 and 2, when a battery pack using an assembled battery in which lithium ion batteries are connected in series and / or connected in parallel is to be provided with a temperature sensing function and an expansion detecting function, the temperature of the battery element is set. A heat conductive sheet to be transmitted to the protection circuit board and a conductor as a means for detecting swelling are required. Further, in Patent Document 3, a sensor in which a temperature detection unit and a pressure detection unit are integrated is used as a means for sensing a temperature rise and expansion of a lithium ion battery. Since the sensor is provided, the required number of conductors increases as the number of stacked batteries increases, and there is a problem that more man-hours are required to connect the output of the expansion detection result to the terminals of the protection circuit board.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lithium ion battery pack that has both a simple structure and a temperature sensing function and an expansion detection function with a small number of man-hours and members.

  In order to solve the above-described problems, a lithium ion battery pack according to the present invention is a battery pack having a battery pack in which a plurality of laminated exterior type lithium ion batteries are stacked, and at the center of the side surface of at least one lithium ion battery. Two types of metal that are fixed at the fixed location and are provided along the surface from the center of the side surface, connected to the anomaly detection circuit in the protection circuit board, covered with an insulating film and connected at one location It has one abnormality detection means which has the temperature detection function which consists of a sheet | seat, It is characterized by the above-mentioned.

  Further, the two kinds of metal sheets may be a combination using an alloy mainly composed of nickel and chromium for a positive leg and an alloy mainly composed of nickel for a negative leg. Further, a combination using copper as a positive leg and nickel as a negative leg may be used. The two types of metal sheets have a thickness of 8 μm or less, a width of 2 mm or less, and two measurement points. It is desirable that the types of metals connect, otherwise they are spaced and coated with an insulating film.

  According to the present invention, one abnormality detecting means that has a temperature sensing function and breaks when the packaging member expands is fixed so as to be in contact with the plane of the assembled battery that uses the laminate film as the packaging material. Thus, it is possible to provide a lithium ion battery pack that has both a temperature sensing function and an expansion detection function of a battery pack having a simple configuration with a small number of man-hours and members.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view in which an abnormality detection unit of a lithium ion battery pack is attached to an assembled battery for explaining an embodiment of the present invention and Example 1; It is the top view which showed the normal state of the abnormality detection means and lithium ion battery based on Example 1 of this invention. It is the top view which showed the case where the abnormality detection part and lithium ion battery which concern on Example 1 of this invention expanded. It is a figure which shows the electrical connection of the lithium ion battery pack of this invention. It is the front view which attached the abnormality detection means of the lithium ion battery pack based on Example 2 of this invention to the assembled battery. It is the front view which attached the abnormality detection means of the lithium ion battery pack based on Example 3 of this invention to the assembled battery. It is a figure which shows a laminated exterior type lithium ion battery, Fig.7 (a) is a top view, FIG.7 (b) is a front view, FIG.7 (c) is a side view.

  In FIG. 7, the battery element 3 from which the positive electrode terminal 21 and the negative electrode terminal 22, which are the outputs of the lithium ion battery, are covered with a laminate film packaging material 4. The positive terminal 21 is made of a metal foil such as aluminum foil, nickel foil, or stainless steel foil, and the negative terminal 22 is made of a metal foil such as copper foil, nickel foil, or stainless steel foil. In addition, it is preferable to use the aluminum laminate film for the laminate film packaging material 4 from weight reduction, workability, and the freedom degree of a shape. When this lithium ion battery 101 falls into an overcharged state, electrolyte gas is generated, and the battery internal pressure increases, the battery is swollen, or the battery element generates heat to accelerate deterioration of the lithium ion battery. There is a case.

  Hereinafter, embodiments of the present invention will be described in detail. In FIG. 1, in the assembled battery 110 composed of lithium ion batteries 111, 112, and 113, the abnormality detecting means 5 is fixed to the fixing points 8 at both ends of the laminate film at the center of the side surface by an adhesive made of a modified silicone resin or the like. As shown in FIG. 2, the abnormality detecting means 5 includes a conductor 6 and an insulating film 7 for coating the conductor 6. The conductor 6 is made of two kinds of sheet-like metals, and an alloy mainly composed of nickel and chrome such as chromel is combined on the leg and an alloy mainly composed of nickel such as alumel on the negative leg. In the negative leg, a combination of alloys mainly consisting of copper and nickel such as constantan is used, the thickness is 3 to 8 μm, the width is 1 to 2 mm each, and the two kinds of metals are in contact at the measurement point, In other cases, it is desirable that the metal interval is 1 mm or less. In addition, it is preferable to use the thickness and the width within the above ranges in view of strength that can withstand bending and workability during installation. The conductor 6 senses the temperature by converting the voltage difference generated between the reference point and the measurement point into a temperature when a difference occurs between the temperature at a certain reference point and the measurement point temperature. It has the characteristic that it can be. Here, when the thickness of the lithium ion battery using the laminate film is as thin as 5 to 6 mm, the heat transfer between the batteries is good, so the temperature measurement point is set at one place on the plane of the laminate film of one battery. Just do it. The material of the conductor 6 is not limited to this as long as it has a temperature detection function. However, if the thickness and width are larger than the above values, the conductor may not break when the battery expands. Therefore, as long as the workability is not impaired, the thickness is preferably thin and the width is preferably narrow. Further, except for the measurement point on the conductor 6, the distance between the two types of metal is a distance that does not contact each metal. Short distance is better for miniaturization. On the other hand, the insulating film 7 is provided for the purpose of preventing the conductor 6 from rust and the like and further protecting the insulation by coating the two kinds of metals of the conductor 6, and the material is a polyester film or a polyimide film. The thickness is preferably 10 μm or less. The material of the insulating film 7 is not limited to this as long as it has insulating properties, but among the films, it is excellent in electrical insulating properties and has flexibility, so that it can be easily processed and handled. It is preferred to use the above for advantages. Further, in order to improve the sensitivity of heat when the battery generates heat, it is preferable that the thickness is thin as long as workability is not impaired.

  Both ends of the abnormality detecting means 5 are connected to the terminals of the abnormality detecting circuit 9, and the abnormality detecting circuit 9 monitors the temperature of the battery by the temperature sensing function of the conductor 6, and when the temperature becomes high, for example, 60 degrees or more. Judge as abnormal. Furthermore, the conductor monitors the conduction state of the battery by reading the resistance value of the conductor, and when the assembled battery 110 has a normal thickness as shown in FIG. 2, the conductor 6 is conductive. And its resistance value is zero. However, when any one or all of the lithium ion batteries 111, 112, 113 are expanded and the entire assembled battery 110 is expanded, the conductor 6 is broken as shown in FIG. 3, and its resistance value is infinite. Therefore, it is determined whether or not the battery has expanded.

  In FIG. 4, the electrical connection of the battery pack 100 which consists of the assembled battery 110 and the protection circuit board 10 is shown. The battery output 2 of the assembled battery 110 is connected to the protection circuit board 10, and the protection circuit board 10 and an external device are connected via an external output terminal 11. The protection circuit board 10 monitors the voltage of the assembled battery output from the battery output 2, and when the battery falls into an overcharge or overdischarge state, the protection circuit board 10 determines that there is an abnormality in the protection circuit. It works to cut off the power supply. Note that the abnormality detection circuit 9 is installed in the protection circuit board 10 as a part of the protection circuit board 10, and monitors the temperature abnormality and expansion of the assembled battery 110, and when the abnormality is determined as a result of the monitoring. Cuts off the energization between the external device and the assembled battery by the internal components in the protection circuit.

Example 1
A first embodiment will be described with reference to FIGS. As shown in FIG. 1, a central portion of a battery pack 110 having a length of 170 mm, a width of 80 mm, and a height of 12 mm constituted by stacking three lithium ion batteries 111, 112, 113 having a height of 170 mm, a width of 80 mm, and a height of 4 mm. The abnormality detection means 5 having a circulation length of 184 mm was attached so as to make one round in the direction crossing the line. As shown in FIG. 2, the anomaly detection means 5 is a conductor having a thickness of 3 μm and a width of 1 mm each made of chromel and alumel in contact with each other at the measurement point. 6 was coated with an insulating film 7 made of a polyester film, and six places were fixed to the fixing places 8 at both ends of the laminate film at the center of the side surface of the lithium ion battery with an adhesive made of a modified silicone resin. An overcharge test was performed on this lithium ion battery pack, and it was confirmed that the conductor 6 was broken as shown in FIG. 3 when the assembled battery 110 was swollen and the circumference length was 204 mm. In this overcharge test, the abnormality detection circuit using the temperature sensing function was not operated.

(Example 2)
A second embodiment will be described with reference to FIG. The material and structure of the assembled battery and the abnormality detecting means 5 are the same as those of the first embodiment, and the abnormality detecting means 5 having a circulation length of 508 mm is attached so as to make a round in the direction crossing the central portion of the assembled battery 110. . As shown in FIG. 5, the abnormality detecting means 5 was attached so that the lithium ion batteries 111, 112, and 113 make a round, and fixed at six places with an adhesive made of a modified silicone resin. The lithium ion battery pack was overcharged with the temperature detection function removed, and it was confirmed that the conductor 6 had broken as shown in FIG. . In the case of Example 2, since the conductor 6 that contacts the swollen battery breaks, it remains in the history of which battery has swollen among the assembled batteries, so it is possible to obtain excellent information such as failure analysis. is there.

Example 3
A third embodiment will be described with reference to FIG. The material and structure of the assembled battery and the abnormality detection means 5 were the same as those in Example 1, and the abnormality detection means 5 having a circumference length of 340 mm was attached so as to make a round in the direction crossing the central portion of the assembled battery 110. . As shown in FIG. 6, the abnormality detecting means 5 is alternately attached so as to be in contact with both surfaces of each layer of the lithium ion batteries 111, 112, and 113, and is fixed at five places with an adhesive made of a modified silicone resin. The lithium ion battery pack was overcharged with the temperature detection function removed, and it was confirmed that the conductor 6 had broken as shown in FIG. . In the case of Example 3 as well, since the conductor 6 in contact with the expanded battery breaks, it remains in the history of which battery has expanded among the assembled batteries, so it is possible to obtain excellent information such as failure analysis. It is.

  In the present invention, by relating to a lithium ion battery using a laminate film whose expansion is more remarkable than that of a metal can case, the conductor 6 has a synergistic effect if any of the lithium ion batteries 111, 112, 113 expands. Since it is pulled, the abnormality detecting means 5 need only have one point. Further, since the thickness is thin, heat transfer between the batteries is good, and therefore, the temperature detection point may be set at one place on the laminate film plane of one battery in the assembled battery 110. In addition, the abnormality detection means of this invention and the installation method of a conductor are not limited to said Example. Moreover, although the assembled battery comprised by three lithium ion batteries was demonstrated in the present Example, you may use for the assembled battery comprised by many lithium ion batteries.

DESCRIPTION OF SYMBOLS 100 Battery pack 101, 111, 112, 113 Lithium ion battery 110 Assembly battery 2 Battery output 21 Positive electrode terminal 22 Negative electrode terminal 3 Battery element 4 Laminate film packaging material 5 Abnormality detection means 6 Conductor 7 Insulating film 8 Fixed location 9 Abnormality detection circuit 10 Protection circuit board 11 External output terminal

Claims (4)

  In a battery pack having an assembled battery in which a plurality of laminate-type lithium ion batteries are stacked, the battery pack is fixed to a fixing portion provided at the center of the side surface of at least one lithium ion battery, and extends from the center of the side surface to the surface of the center portion. And an abnormality detection means having a temperature detection function composed of two kinds of metal sheets covered with an insulating film and connected at one place, connected to an abnormality detection circuit in the protection circuit board. Lithium ion battery pack.   2. The lithium ion battery pack according to claim 1, wherein the two kinds of metal sheets are a combination using an alloy mainly composed of nickel and chromium for a positive leg and an alloy mainly composed of nickel for a negative leg. .   2. The lithium ion battery pack according to claim 1, wherein the two kinds of metal sheets are a combination using an alloy mainly composed of copper for a positive leg and nickel for a negative leg.   The two types of metal sheets have a thickness of 8 μm or less, a width of 2 mm or less, and the two types of metal are connected at the measurement point. Otherwise, the metals are spaced and coated with an insulating film. The lithium ion battery pack according to any one of claims 1 to 3.

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