JP4214985B2 - Battery pack - Google Patents

Description

  The present invention relates to a battery pack applied to, for example, a lithium ion polymer secondary battery.

  In recent years, portable electronic devices such as notebook personal computers, mobile phones, and PDAs (Personal Digital Assistants) have become widespread, and lithium ion batteries having advantages such as high voltage, high energy density, and light weight have been widely used as power sources.

  Furthermore, as a countermeasure against liquid leakage that becomes a problem when using a liquid electrolyte, for example, an electrolyte that uses a gel polymer film in which a polymer is impregnated with a nonaqueous electrolyte, or an all-solid electrolyte is used. A lithium ion polymer secondary battery using an electrolyte has been put into practical use.

  A polymer lithium ion battery has a positive electrode, a negative electrode, and a polymer electrolyte, and has a cell structure in which a battery element from which a lead is led out from the positive electrode and the negative electrode is covered with an exterior material such as an aluminum laminate. Further, the cell is configured to be housed in a box-shaped plastic mold case composed of upper and lower cases together with a wiring board on which a circuit portion is mounted. Patent Document 1 below describes an example of a lithium ion polymer secondary battery having such a configuration.

Japanese Patent Laid-Open No. 2002-8606

  In this specification, a belt-like positive electrode and a belt-like negative electrode are laminated via a polymer electrolyte and / or a separator, wound in the longitudinal direction, and lead terminals are led out from the positive electrode and the negative electrode, respectively. This is called a battery element. And what coat | covered the battery element with the exterior film is called a cell. Further, a cell in which a necessary circuit such as a protection circuit is added to the cell is referred to as a battery pack.

  In the conventional configuration in which the battery element is accommodated in the mold case, the thickness of the mold case is about 0.3 to 0.4 mm, and considering the double-sided tape for fixing and the tolerance, the thickness of the cell is 0. The thickness increased by about 8-1 mm. In addition, a shape for ultrasonic welding of the upper and lower mold cases is required also in the outer peripheral direction, and therefore, a thickness of about 0.7 mm is required. As a result, the battery pack was forced to increase by 1.3 to 1.4 times the volume of the cell.

  In addition, when a design is required for the exterior portion of the pack, it is necessary to apply a printed label. In order to prevent a decrease in volume energy density as much as possible, it is necessary to apply a thin label with an adhesive. As the label to be attached becomes thinner, the risk of air entering between the label and the battery and the occurrence of process defects such as label slippage increase.

  Furthermore, battery packs are expensive and easy to imitate, and as countermeasures against them, microcomputers were placed on the pack substrate to communicate with the main unit or mounted ID resistors, but this was expensive. There was a harmful effect.

  Furthermore, there is a tendency that countermeasures for imitation become more difficult as the structure of the battery pack is simplified.

  Accordingly, an object of the present invention is to provide a battery pack that can suppress an increase in volume when the battery pack is configured as much as possible without deteriorating mechanical strength and safety.

  Another object of the present invention is to provide a battery pack that is low in cost and difficult to be imitated.

To achieve the above object, a first aspect of the present invention is a battery pack having a battery cell of the polymer battery, between the open state of the flexible covering member and the open state of the rigid outer package of disposing the battery element, close overlapping the flexible covering member and the rigid covering member, the battery element is surrounded by the ends of the rigid covering member are bonded by heat welding, into an elliptical shape in which both sides outwardly bulging This is a molded battery pack.

A second aspect of the invention, the outer Paneling consists first and second laminate of substantially the same size, the first laminate has a soft aluminum metal layer, the second laminate hard The battery element is housed in a recess formed in the first laminate material, having an aluminum metal layer , and the first and second laminate materials are stacked so that the opening of the recess is covered by the second laminate material, around the opening, or the opposing surfaces of the first laminate and the second laminate are heat-welded, in the outer bottom surface of the recess of the first laminate, both end portions of the first laminate material is in contact, Alternatively, the first seam where the end faces are opposed to each other through a slight gap and the both ends of the second laminate material are in contact with each other, or the end faces are opposed to each other via a slight gap. The second seam is located , The opposing surfaces of the first and second laminate is a battery pack that has been adhered.

  According to the present invention, since the cells in the pack can be maximized, a high pack energy density can be obtained. When the cell is placed in the exterior mold case, a gap is generated between the case and the internal cell, and the conventional problem of lowering the volume energy density of the battery pack can be solved.

  In this invention, even if there is no frame or the like on the side part of the pack, the outer peripheral surface of the battery element is covered with a hard metal laminate film. Can keep.

  In the present invention, it is only necessary to have a frame for holding the wiring board, and the number of parts such as an exterior mold case can be reduced, and the cost can be greatly reduced.

  Unlike the conventional cell, the cell according to the present invention can improve the strength.

  In the present invention, it is possible to manufacture the cell portion and the pack portion in a series of steps, and the time required for manufacturing can be shortened.

  In the present invention, since a hard aluminum laminate film printed in advance is used, it is not necessary to wind an exterior label, and the yield can be improved and the cost can be reduced.

  In this invention, it contributes to prevention of imitation of a pack by printing in the stage which manufactures a cell.

  Also, printing a pattern that is difficult to imitate helps prevent imitation of the pack.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of a battery pack of a lithium ion polymer secondary battery to which the present invention is applied. Reference numerals 1A and 1B indicate first and second laminate materials, respectively, and a battery element is covered with the laminate materials 1A and 1B to constitute a cell. The battery element is a lithium ion polymer secondary battery, and has, for example, a plate shape having a long side of 49 mm, a short side of 40 mm, and a thickness of 4.4 mm.

  The laminate materials 1A and 1B are films having a three-layer structure in which an adhesive layer and a surface protective layer are arranged on both surfaces of a metal layer, as will be described later. On the outer surface of the cell, the surface protective layer of the laminate 1B appears as a whole. 1B shows a state in which the battery element 14 appears on the surface by cutting and removing the laminates 1A and 1B along the line P. FIG.

  Lead terminals 2 and 3 connected to the positive electrode and the negative electrode of the battery element are derived. The lead terminals 2 and 3 and the protection circuit are joined by resistance welding, ultrasonic welding, or the like. As shown in FIG. 1A, a circuit board 6 on which a protection circuit bonded to a battery element is mounted is inserted between the top cover 4 and the board holder 5 to form one block. The protection circuit of the circuit board 6 includes a temperature protection element that cuts off the current path of the cell when the temperature becomes high, such as a PTC or thermistor.

  Next, after pouring an adhesive or the like into the end face side where the lead terminals 2 and 3 are projected (hereinafter referred to as the “top side” as appropriate), the top cover 4, the substrate holder 5, and the circuit board 6 are integrated. Insert a block. Thereafter, the exposed portion of the adhesive layer of the cell laminate 1B and a top cover made of resin, for example, polypropylene (PP) are thermally welded to improve the adhesive strength.

  Thereafter, an adhesive is poured in advance on the opposite side (hereinafter referred to as the bottom side) of the end surface where the lead of the cell portion is protruding, and the resin rear cover 7 (FIG. 1C) is inserted. Further, the rear cover may be molded from a hot melt material instead of the rear cover 7. Finally, an exterior label 8 (FIG. 1D) made of an aluminum-deposited PET film with an adhesive is attached.

  An embodiment of the cell unit will be described with reference to FIG. In one embodiment, two types of laminate materials 1A and 1B are used. The laminating material 1A is drawn in a predetermined shape with a mold in advance to insert a battery element. The battery element is housed in a recess formed by drawing. The heat welding sheet 12 is disposed on the outer surface at a position corresponding to the bottom surface of the recess.

  In FIG. 3, reference numeral 14 indicates a battery element. In the battery element 14, a belt-like positive electrode and a belt-like negative electrode are laminated via a polymer electrolyte and / or a separator, wound in the longitudinal direction, and lead terminals 2 and 3 are led out from the positive electrode and the negative electrode, respectively. .

  In the positive electrode, a positive electrode active material layer is formed on a strip-shaped positive electrode current collector, and a polymer electrolyte layer is further formed on the positive electrode active material layer. The negative electrode has a negative electrode active material layer formed on a strip-shaped negative electrode current collector, and a polymer electrolyte layer formed on the negative electrode active material layer. The lead terminals 2 and 3 are joined to the positive electrode current collector and the negative electrode current collector, respectively. As the positive electrode active material, the negative electrode active material, and the polymer electrolyte, materials already proposed can be used.

The positive electrode can be composed of a metal oxide, a metal sulfide, or a specific polymer as the positive electrode active material depending on the type of the target battery. For example, in the case of constituting a lithium ion battery, LixMO ₂ (wherein M represents one or more transition metals, x is different depending on the charge / discharge state of the battery, and is usually 0.05 or more and 1. Lithium composite oxide mainly composed of 10 or less) can be used. As the transition metal M constituting the lithium composite oxide, Co, Ni, Mn and the like are preferable.

Specific examples of such a lithium ion composite oxide include LiCoO ₂ , LiNiO ₂ , LiNiyCo _1-y O ₂ (where 0 <y <1), LiMn ₂ O _{4 and the} like. . These lithium composite oxides can generate a high voltage and have an excellent energy density. _{Further, TiS 2, MoS 2, NbSe} 2, V 2 O no lithium metal sulfides such as ₅ or may be used an oxide as the positive electrode active material. A plurality of these positive electrode active materials may be used in combination for the positive electrode. Further, when forming the positive electrode using the positive electrode active material as described above, a conductive agent, a binder or the like may be added.

As the negative electrode material, a material capable of doping and dedoping lithium can be used. For example, a non-graphitizable carbon material or a carbon material such as a graphite material can be used. More specifically, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke), graphites, glassy carbons, organic polymer compound fired bodies (phenolic resin, furan resin, etc.) at an appropriate temperature. Carbon materials such as those obtained by firing and carbonization), carbon fibers, activated carbon, and the like can be used. Further, lithium doped as the dedoping can material, may be used polyacetylene, an oxide of _2, such as polymers and SnO polypyrrole. When forming the negative electrode from such a material, a binder or the like may be added.

  The polymer electrolyte is one in which a polymer material, an electrolytic solution, and an electrolyte salt are mixed to form a gelled electrolyte into the polymer. The polymer material has a property compatible with the electrolytic solution, such as silicon gel, acrylic gel, acrylonitrile gel, polyphosphazene modified polymer, polyethylene oxide, polypropylene oxide, and composite polymers, cross-linked polymers, modified polymers thereof, etc. Alternatively, as the fluorine-based polymer, for example, a polymer material such as poly (vinylidene fluoride), poly (vinylidene fluoride-co-tetrafluoropropylene), or poly (vinylidene fluoride-co-trifluoroethylene), and a mixture thereof may be used. used.

As the electrolyte component, the above-described polymer material can be dispersed, and for example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or the like is used as an aprotic solvent. As the electrolyte salt, one that is compatible with a solvent is used, and a combination of a cation and an anion is used. As the cation, an alkali metal or an alkaline earth metal is used. As the anion, Cl ⁻ , Br ⁻ , I ⁻ , SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , CF ₃ SO ₃ ^{− and the} like are used. Specifically, lithium hexafluorophosphate or lithium tetrafluoroborate is used in the electrolyte salt at a concentration at which it can be dissolved in the electrolytic solution.

  In one embodiment, the laminate materials 1A and 1B have a function as an exterior material for the battery element described above. In the conventional lithium ion polymer secondary battery, only one laminate material is used, whereas in one embodiment, two laminate materials 1A and 1B are stacked.

  FIG. 5 shows a laminated structure of the laminate material 1A. As the laminate material 1A, a material suitable for drawing and suitable for forming a recess into which a battery element is inserted is used, and is softer than the laminate material 1B. In order from the inner side (side in contact with the laminate 1B), a polypropylene (PP) layer 15A as an adhesive layer, a soft aluminum metal layer 16A as a metal layer, and a nylon layer or PET (polyethylene terephthalate) layer 17A as a surface protective layer are provided. .

  The polypropylene layer 15A has a function of preventing the deterioration of the polymer electrolyte. As the polypropylene layer 15A, unstretched polypropylene (CPP) or the like is used. For example, a polypropylene (PP) layer 15A having a thickness of about 30 μm is formed.

  The soft aluminum metal layer 16A has a function of preventing moisture from entering the inside. As the soft aluminum metal layer 16A, annealed aluminum (3003-O JIS H 4160) or (3004-O JIS H 4160) or the like having a thickness in the range of about 30 μm to 130 μm is used. The nylon layer or PET layer 17A has a surface protecting function. The nylon layer or the PET layer 17A has a thickness of about 10 μm to 30 μm.

  The other laminate material 1B is a hard laminate material that maintains its shape after bending and can withstand deformation from the outside. Laminate 1B has a polypropylene layer as an adhesive layer, a hard aluminum metal layer, and a nylon layer or a PET layer as a surface protective layer.

  The polypropylene layer and nylon layer or PET layer of the laminate material 1B are the same as those of the laminate material 1A. The hard aluminum metal layer is made of aluminum (3003-O JIS H 4160) or (3004-O JIS H 4160) without annealing, and has a thickness in the range of about 30 μm to 130 μm. In addition, the thickness of each layer of the laminating materials 1A and 1B is selected in consideration of the total thickness.

  The manufacturing method of the cell part in one Embodiment is demonstrated. The laminating material 1 </ b> A is deep-drawn in advance to insert the battery element 14. The battery element 14 is housed in a recess formed in the laminate material 1A. In FIG. 2A, the outside of the bottom surface of the recess appears, and the opening of the recess is located on the surface opposite to the bottom surface.

  Next, the laminate material 1B is arranged so as to overlap the laminate material 1A so that the polypropylene layers are opposed to each other so as to cover the opening surface of the recess. In this case, as shown in FIG. 2A, the positional relationship between the laminate materials 1A and 1B is shifted. Here, the laminate material 1 </ b> A has a top-side long side 21 and a bottom-side long side 22 having the same length, and has a left short side 23 and a right short side 24 having the same length. Similarly, the laminate material 1B has a top-side long side 31 and a bottom-side long side 32 having the same length, and has a left short side 33 and a right short side 34 having the same length. The left and right indicate the positional relationship when viewed from the drawing.

  The top-side long sides 21 and 31 and the bottom-side long sides 22 and 32 have substantially the same length. The length of this long side is such that the short sides facing each other (short sides 23 and 24, short sides 33 and 34) are in contact with each other in a state of enclosing the battery element storage portion, or the end surfaces of the short sides are slightly spaced. It is selected to be opposed to each other.

  A pair of notches are formed on the extension of the side wall of the battery element storage portion on the top side long side 31 of the laminate material 1B. The bottom long sides 22 and 32 are also substantially equal to each other. The short sides 23 and 24 of the laminate 1A are slightly shorter than the short sides 33 and 34 of the laminate 1B. Therefore, when the laminate materials 1A and 1B are laminated, only the laminate material 1B exists in the vicinity of the edge along the long side on the top side. As described above, when a resin top cover is attached, the peripheral surface of the top cover is thermally welded to the polypropylene layer of the laminate material 1B. Note that the adhesive layer of the laminate 1B may be exposed even in the vicinity of the bottom side end face.

  As shown in FIG. 2A, the battery element storage recess of the laminate 1A is formed at a position slightly shifted to the right with respect to the center position. The laminate material 1B is laminated at a position slightly shifted to the right side with respect to the laminate material 1A. Therefore, in a state where the laminate materials 1A and 1B are laminated, as shown in FIG. 2A, a left region where only the laminate material 1A is located and a right region where only the laminate material 1B is located are generated. The reason for shifting the position is to allow the polypropylene layer of one laminate material to adhere to the other laminate material with a certain width in the vicinity of the position of the joint of the laminate materials 1A and 1B. It is.

  Then, in the state of arrangement as shown in FIG. 2A, the electrode element is inserted, and the four sides around the opening of the recess are sealed while being decompressed. In this case, the entire portion where the polypropylene layers overlap may be heat-welded. After that, the sealed battery element is put in the mold, and the battery element is molded with the mold so that the end faces 11A and 11B on both sides swell outward as shown in FIGS. 4 and 6B. . 6A shows a state where the battery element 14 appears on the surface by cutting and removing the laminates 1A and 1B along the line P, as in FIG. 1B.

  Next, as shown in FIG. 2A, the heat welding sheet 12 having a predetermined shape is inserted outside the bottom surface of the recess. The heat welding sheet 12 is an auxiliary member for bonding the nylon layers or PET layers 17A of the laminate material 1A, that is, bonding nylons or PETs together by applying a high temperature. Preferably, the thickness is about 10 to 60 μm from the relationship of the total thickness and has a melting point of about 100 ° C. The melting point of the heat-bonding sheet 12 is preferably such that it does not affect the battery element with heat.

  Then, from the opened state shown in FIG. 2A, the laminating materials 1A and 1B are folded inward so that the recesses in which the battery elements are accommodated are wrapped, and heat welding is performed from the outside. Do and fix the closed state. 4 and 6 show a state in which the laminate material is closed and sealed as described above.

  As shown in FIG. 4 and FIG. 6, a seam L <b> 1 in which the short sides 33 and 34 of the laminate 1 </ b> B are in contact with each other or their end faces face each other through a slight gap is generated on the outside. In addition, a seam L2 in which the short sides 23 and 24 of the laminating material 1A are in contact with each other or their end faces face each other through a slight gap is formed inside the laminating material 1B.

  FIG. 6C shows a cross section of the seams L1 and L2. Although not shown, the nylon layer or PET layer 17A of the laminate material 1A is located below the heat-welded sheet 12. When the laminating materials 1A and 1B are folded inward and closed, the upper and lower relations of the two are reversed on the upper side of the heat welding sheet 12, the laminating material 1A is positioned on the lower side, and the laminating material 1B is positioned on the upper side. In FIG. 6C, reference numeral 15B indicates a polypropylene layer of the laminate material 1B, reference numeral 16B indicates a hard aluminum metal layer, and reference numeral 17B indicates a nylon layer or a PET layer.

  As shown in FIG. 6C, the nylon layer or PET layer 17 </ b> A of the laminate material 1 </ b> A is positioned in contact with the upper side of the heat welding sheet 12. Accordingly, the nylon layer or the PET layer 17A has a structure in which the heat-welded sheet 12 is sandwiched, and nylon or PET can be bonded to each other by applying heat from the outside. Further, since the polypropylene layers 16A and 16B of the laminate materials 1A and 1B face each other, the polypropylene layers 16A and 16B can be bonded by applying heat from the outside.

  As described above, a battery pack in which the hard laminate material 1B also serves as an exterior material is manufactured without using a resin box-shaped case and without arranging resin frames on both sides. Can do.

  In the above-described embodiment, a battery pack configured so as not to attach the exterior label 8 can also be manufactured. In this case, in the manufacturing process described above, instead of the second laminate material 1B, a laminate material 1C on which patterns or characters are printed in advance is used.

  FIG. 7 is an enlarged cross-sectional view of the laminate material 1C. As shown in FIG. 7, the laminate material 1C includes a polypropylene layer 41 as an adhesive layer, a hard aluminum metal layer 42, a nylon layer as a surface protective layer 43, a PET (polyethylene terephthalate) layer, or a PEN (polyethylene naphthalate) layer. Have. Characters or patterns are printed on the inner surface 44 and / or the outer surface 45 of the surface protective layer 43.

  FIG. 8 is a schematic view showing an example of a laminate material 1C. As shown in FIG. 8, an example pattern that is difficult to be imitated is printed on the surface of the laminate 1 </ b> C. In addition to this pattern, a pack name, a barcode, a two-dimensional code, etc. may be printed. Furthermore, a pattern that is difficult to be imitated is suitable. For example, a watermark or a hologram may be printed. Specifically, a pattern may be printed on the inner surface 44 and text, a two-dimensional code, or the like may be printed on the outer surface 45.

  As shown in FIG. 8, the laminate material 1 </ b> C on which characters or patterns are printed is produced by cutting one cell at a time from the laminate base material 101. As described above, by using the laminate material 1C on which patterns or characters are printed in advance, it is not necessary to attach the exterior label 8, so that the volume energy density can be improved. Moreover, since the pattern or the character is printed at the stage of manufacturing the cell, it contributes to prevention of imitation.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, since the inner laminate material 1A does not appear on the surface, the surface protective layer is omitted, and polypropylene (PP) as the first and second adhesive layers on both sides of the soft aluminum metal layer 16A (see FIG. 5). It is good also as a laminated structure which arranges a layer. In this case, since the adhesive layers of the laminating material 1A face each other, the heat welding sheet 12 can be omitted. Moreover, you may use an adhesive material besides heat welding.

  Further, in the present invention, the laminate materials 1A and 1B are bent inward to form openings in the top portion and the bottom portion, the circuit board is welded to the lead terminals derived from the openings, and then the circuit board is separated. The circuit board holder may be supported by the circuit board holder created in the process, and the circuit board holder may be inserted into the opening while bending the lead terminal.

It is a basic diagram for demonstrating one Embodiment of the battery pack to which this invention was applied. It is a basic diagram which shows the state in the middle of manufacture of the cell of one Embodiment of this invention. It is a perspective view of the battery element of one Embodiment of this invention. It is a perspective view of the cell of one Embodiment of this invention. It is a basic diagram which shows the laminated structure of the laminate material in one Embodiment of this invention. It is a basic diagram of the cell of one Embodiment of this invention. FIG. 7 is an enlarged cross-sectional view of another example of a laminate material. FIG. 8 is a perspective view of a laminate material.

Explanation of symbols

1A, 1B, 1C ... Laminate material 2 ... Lead terminal 6 ... Circuit board 15A, 15B ... Adhesive layer 16A, 16B ... Metal layer 17A, 17B ... Surface protective layer

Claims (8)

Outer Paneling is from the first and second laminate having substantially the same size,
The first laminate material has a soft aluminum metal layer, the second laminate material has a hard aluminum metal layer,
The battery element is housed in the recess formed in the first laminate material,
The first and second laminate materials are stacked so that the second laminate material covers the opening of the recess, and the opposing surfaces of the first laminate material and the second laminate material are disposed around the opening. Is heat welded ,
On the outside of the bottom surface of the recess of the first laminate material, both first ends of the first laminate material are in contact with each other, or a first seam in which the end surfaces face each other with a slight gap therebetween, The first and second laminate materials are arranged so that both end portions of the second laminate material are in contact with each other or a second seam formed by facing each other through a slight gap is positioned. A battery pack with the opposite surface bonded . In claim 1,
A battery pack that is shaped like an ellipse with both side surfaces bulging outward. In claim 1 ,
The position of the first seam ;
The battery pack position and is shifted to the second seam. In claim 1 ,
It said first laminate material, an adhesive layer, and the soft aluminum metal layer, and a surface protective layer made are laminated in this order,
The second laminate material is formed by laminating an adhesive layer, the hard aluminum metal layer, and a surface protective layer in this order,
A battery pack in which the adhesive layers of the first and second laminate materials are stacked opposite to each other. In claim 4,
A battery pack in which the adhesive layer is a heat-welded adhesive layer, and the surface protective layers of the first laminate material are welded to each other via a heat-welded sheet outside the bottom surface of the recess. In claim 1 ,
The first laminate is assumed that the first adhesive layer and the soft aluminum metal layer and the second adhesive layer are laminated in this order,
The second laminate is assumed that the adhesive layer and the hard aluminum metal layer and the surface protective layer are laminated in this order,
A battery pack in which one of the first and second adhesive layers of the first laminate material and the adhesive layer of the second laminate material are opposed to each other. In claim 1 ,
The soft aluminum metal layer of the first laminate material is annealed aluminum;
The battery pack, wherein the hard aluminum metal layer of the second laminate material is aluminum without annealing treatment. In claim 4 ,
A battery pack in which characters or patterns are printed outside and / or inside the surface protective layer of the second laminate material.