JP2005327593A - Cell battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell battery pack which has a smaller number of parts, can perform shielding from outside noises by simple structure, and moreover can be assembled easily. <P>SOLUTION: In the cell battery pack, a core pack 10 equipped with a battery cell 15, a protection element 2, and a protective circuit board 4 is covered with a covering label 6. Further, the potential of the surface of the cell pack 15 may be the same as that of the covering label 6 by causing an adhesive agent 6a applied onto the covering label 6 to be conductive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a battery pack, and more particularly, to a structure that shields a battery pack with an exterior label attached and protects an internal electric circuit such as a protection circuit from external noise.

  In recent years, battery packs such as lithium ion secondary batteries have been used as power sources for various portable electronic devices such as mobile phones.

  Although a single rectangular battery cell corresponding to the voltage and current required for these portable electronic devices is used, it has a voltage and current capacity that is difficult to handle with a single battery cell. In the case of electronic devices that are required, a battery pack is used that can output a predetermined voltage and current capacity by conductively connecting a plurality of battery cells in series or in parallel.

  In addition, since a battery pack provided with such a plurality of battery cells has a large charge / discharge capacity, a dangerous situation such as overheating, burnout, or explosion of the battery at the time of abnormality such as overcharge, overdischarge, short circuit, etc. Therefore, a protection circuit board made up of a charge / discharge protection circuit that cuts off the current and protects the battery cell is installed on the side surface of the battery cell.

  However, this protection circuit board has a tendency that the circuit impedance tends to increase with the recent power saving, and therefore, there is a problem that it is easily affected by external noise.

  In addition, battery packs installed in various portable electronic devices may be used, stored, or left in various environments, and various noise environments are expected, not limited to static electricity. Measures are becoming necessary.

  Therefore, a battery pack case having a configuration as disclosed in Patent Document 1 has been proposed. That is, in Patent Document 1, a battery cell and a protection circuit board are assembled inside a frame of a battery pack case, and a metal thin plate having a shielding effect is attached to the upper and lower surfaces to protect the protection circuit board from external noise. Was.

  However, in Patent Document 1, since a separate component such as a metal thin plate is used to shield external noise, the structure of the case becomes complicated, and the screws between the cases must be screwed. It took time to assemble the battery pack.

Japanese Patent No. 3421471

  An object of the present invention is to provide a battery pack that solves the above-described problems, has a small number of parts, can shield external noise with a simple structure, and can be easily assembled.

  The present invention is a battery pack in which a core pack having at least one battery cell and a protection circuit for protecting the battery cell is covered with an exterior label coated with an adhesive, the adhesive being a conductive material. The battery pack is characterized in that the surface of the battery cell and the exterior label have the same potential.

  Moreover, this invention is said battery pack characterized by the said battery cell being a lithium secondary battery.

  That is, the battery pack of the present invention has a protective circuit by providing conductivity to the adhesive of the exterior label so that it has the same potential as the surface of the battery cell when it is attached to the battery cell, and covering it with the exterior label. It is characterized in that the internal electric circuit such as is cut off from external noise.

  According to the present invention employing the above-described configuration, it is possible to provide a battery pack that has a small number of parts, can shield external noise with a simple structure, and can be easily assembled.

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

  FIG. 1 is an explanatory diagram of a core pack and an exterior label used in a battery pack according to an embodiment of the present invention, FIG. 1 (a) is a plan view of the core pack, and FIG. 1 (b) is an exterior label. FIG. FIG. 2 is a diagram illustrating a configuration of a protection circuit for a battery pack according to an embodiment of the present invention. FIG. 2 (a) is a diagram illustrating a state before an exterior label is applied, and FIG. It is a figure which shows the state after affixing an exterior label.

As shown in FIG. 1A, the core pack used in the battery pack according to the embodiment of the present invention includes a square battery cell 15, a protection element 2, and a protection circuit board 4. The prismatic battery cell 15 has a separator made of a polymer porous film such as polyethylene or polypropylene interposed therebetween, so that lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO _2). ), Etc., and a negative electrode active material made of a graphite (non-graphitizable carbon) -based compound or a coke (easi-graphitizable carbon) -based compound was applied. A negative current collector made of copper foil or the like is wound to produce a jelly roll as a power generation element, which is stored in a battery can made of aluminum, steel, etc., and electrolyzed with an alkaline electrolyte, an acidic electrolyte, an organic electrolyte, etc. After injecting the liquid, the electrode header is sealed and manufactured by welding it to the battery can. When an aluminum can is used, the surface of the battery cell (can) becomes a positive electrode because it is electrically connected to the positive electrode. When a steel can is used, the battery cell (can can be connected to the negative electrode). ) Is the negative electrode. In the example of FIG. 1A, the battery can is an aluminum can, which is connected to the positive electrode 5a and has a positive surface.

  As shown in FIG.1 (b), the exterior label 6 used for the battery pack in one embodiment of this invention is the magnitude | size which can cover both the planes of a core pack, and four side surfaces which continue with them. The thickness is about 0.05 to 0.2 mm. Moreover, a synthetic resin, a nonwoven fabric, etc. can be used as a base material with the form of a single layer, or those laminated | stacked. Examples of the synthetic resin include films and sheets made of various thermoplastic resins. Examples of the thermoplastic resin include high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, polyolefin resins such as poly-4-methylpentene-1, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly Polyester such as butylene terephthalate, styrene resin such as polystyrene, nylon, polyimide, polycarbonate, and the like can be used.

The conductive pressure-sensitive adhesive 6a to be applied to a portion where the exterior label 6 is bonded to the core pack is formed by mixing a known organic or inorganic conductive compound with a known acrylic pressure-sensitive adhesive or rubber pressure-sensitive adhesive. Therefore, it is preferable to maintain the surface electric resistance value or the volume electric resistance value within the range of 10 ⁷ Ω to ^{10 10} Ω depending on the amount of the conductive compound mixed. Examples of the base material include acrylic, rubber, polyester, polyurethane, and the like. An adhesive can be used individually or in combination of 2 or more types.

  As an acrylic pressure-sensitive adhesive, an acrylic polymer is used as a pressure-sensitive adhesive component, and various additives such as a crosslinking agent, a tackifier, a softening agent, an anti-aging agent, a filler, and a pigment may be blended if necessary. Good. Examples of the acrylic polymer include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl ( (Meth) acrylate, isoamyl (meth) acrylate, lauryl (meth) acrylate, isomyristyl (meth) acrylate, and other (meth) acrylic acid alkyl esters having about 1 to 14 carbon atoms as the main component, and this can be used as needed. Monomer mixture in which other monomers such as (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, (meth) acrylonitrile, vinyl acetate, N-vinyl-2-pyrrolidone and styrene are added as polymerizable modifying monomers For copolymerization Ri can be produced.

  The rubber-based adhesive includes, for example, an adhesive using natural rubber, styrene-butadiene rubber, polyisobutylene, styrene-isoprene rubber and the like. In addition, as the polyester-based pressure-sensitive adhesive, for example, a polyester including an aliphatic carbonate diol (for example, a carbonate diol obtained by a reaction of a diol component such as butanediol and a carbonate compound such as ethylene carbonate) as an essential polyol component The thing which has a polymer as a main ingredient is mentioned.

  In the present invention, the conductive compound is appropriately dispersed and used in the above-mentioned pressure-sensitive adhesive. Examples of the conductive compound include metals such as copper, gold, silver, nickel, aluminum, stainless steel, iron, chromium, titanium, cobalt, molybdenum, platinum, tungsten, tantalum, niobium, palladium, and solder alloys, or alloys thereof (copper alloys). Carbon powder such as metal powder or metal fiber, zinc oxide, indium oxide, titanium oxide, titanium black, etc., carbon material such as acetylene black, ketjen black, natural graphite, artificial graphite Conductive polymer particles made of conductive polymer such as carbon powder or carbon fiber, polypyrrole, polyaniline, polyacetylene, polythiophene, polyphenylene vinylene, polyacene, and various materials such as these powders, fibers or particles (metal, alloy, metal Oxide, Material charges, conductive polymers, etc.) are coated with particles (e.g., fine particles made of copper or silver coated with a precious metal) or the like can be used. A conductive compound can be used individually or in combination of 2 or more types.

  The battery pack of the present invention can be obtained by using the exterior label and the adhesive having such a configuration, applying the adhesive to the adhesion portion of the exterior label, and attaching the adhesive to the core pack of FIG.

  Next, protection from the external noise of the protection circuit board in the battery pack of the present invention is performed as follows. As shown in FIG. 2A, the protection circuit in the battery pack includes a secondary battery 1 such as a lithium secondary battery, a temperature protection and a current interruption function, and a PTC element that interrupts the current when the temperature rises. , A protective element 2 such as a thermal fuse, a control IC 3 that protects overcurrent and overdischarge, a discharge control switch SW1 that turns on / off a discharge current that is a current in a specific direction, and a charge that turns on / off a charge current And a control switch SW2. The control IC 3 detects the battery cell voltage and the voltage between the control switch elements in order to protect overcharge and overdischarge, and turns on / off the discharge current switch SW1 and the charge control switch SW2 based on the detected voltage. Including a circuit to be controlled. In addition, it becomes such a structure also when a nonelectroconductive adhesive is apply | coated and used for an exterior label.

  When the exterior label is attached to the core pack, as shown in FIG. 2B, the electric potential of the conductive adhesive on the surface of the battery cell and the exterior label becomes the same. Therefore, in the case of FIG. 2 (a), noise from the outside is caused to enter as indicated by an arrow 20, but in the case of FIG. 2 (b), the conductive adhesive of the exterior label is attached to the surface of the battery cell. , The protection circuit board can be shielded from noise from the outside.

  By attaching an exterior label coated with a conductive adhesive in this way to the cell, the entire battery pack is shielded by the surface potential of the battery cell (a positive electrode for aluminum cans and a negative electrode for steel cans). The protection circuit of the battery pack can be protected from external noise and its malfunction can be prevented.

  Further, in the present invention, it is not necessary to use a separate part for shielding external noise, the number of parts is reduced, and the structure is simple. Therefore, since the number of parts is small and the structure is simple, the battery pack can be easily assembled.

Explanatory drawing of the core pack and exterior label which are used for the battery pack in one embodiment of this invention. FIG. 1A is a plan view of the core pack. FIG.1 (b) is a top view of an exterior label. The figure which shows the structure of the protection circuit of the battery pack in one embodiment of this invention. Fig.2 (a) is a figure which shows the state before sticking an exterior label. FIG.2 (b) is a figure which shows the state after sticking an exterior label.

Explanation of symbols

1 Secondary battery 2 Protection element 3 Control IC
4 Protection Circuit Board 5a Positive Electrode 5b Negative Electrode 6 Exterior Label 6a (Conductive) Adhesive 10 Core Pack 15 Battery Cell 20, 30 (Indicates Noise Propagation Direction) Arrow SW1 Discharge Control Switch SW2 Charge Control Switch

Claims (2)

  A battery pack in which a core pack having at least one battery cell and a protection circuit for protecting the battery cell is covered with an exterior label coated with an adhesive, wherein the adhesive has conductivity. The battery pack is configured such that the surface of the battery cell and the exterior label have the same potential.   The battery pack according to claim 1, wherein the battery cell is a lithium secondary battery.

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