JP4639819B2 - Battery pack - Google Patents

Description

  The present invention relates to a battery pack in which a battery element is housed in an exterior material.

  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.

  Further, as a countermeasure against liquid leakage that becomes a problem when using a liquid electrolyte, for example, a lithium polymer secondary battery using a gel polymer film obtained by impregnating a polymer with a nonaqueous electrolyte as an electrolyte, and an electrolyte Lithium polymer secondary batteries using an all-solid electrolyte have been put into practical use.

  A lithium polymer secondary battery includes a positive electrode, a negative electrode, and a polymer electrolyte, and a battery element in which electrode leads are led out from the positive electrode and the negative electrode, respectively, is configured as a cell covered with an exterior material such as an aluminum laminate. Furthermore, 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.

JP 2002-260608 A

  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 tolerance, the thickness of the cell is 0. The thickness increased by about 8 to 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 is forced to increase by 1.3 to 1.4 times the volume of the cell.

  In view of this, the present inventor has housed the battery element in a hard exterior material having first and second openings at both ends, and the first and second manufactured by resin molding with respect to the first and second openings. A battery pack is proposed in which two covers are fitted, and a circuit board to be joined to an electrode lead of a battery element is housed in a first cover fitted in a first opening.

  This battery pack is excellent in volumetric efficiency (electric capacity per volume / 1 battery pack), easy to assemble the battery pack, and excellent in productivity. However, according to the knowledge of the present inventor, since the outer shape is simple, it is considered that the positive and negative electrodes are reversely loaded. In view of this, it is conceivable to provide convex portions on the end face to prevent reverse loading of the positive and negative electrodes of the battery pack. However, in this case, the volume efficiency of the battery pack is reduced.

  Therefore, an object of the present invention is to provide a battery pack that can prevent reverse loading of positive and negative electrodes without causing a decrease in volumetric efficiency.

In order to solve the above-mentioned problems, the present invention is a resin that is contained in at least one opening in which a square or flat battery element is housed in a hard exterior material having openings at both ends, and at least an electrode terminal lead is led out. In a rectangular or flat battery pack in which a cover manufactured by molding is fitted, and a circuit board to be joined to the electrode terminal lead of the battery element is housed in a cover fitted in one opening,
The cover has recesses on both sides of one long side,
The exterior material has a notch for exposing at least the concave portion of the cover,
The battery pack is characterized in that at least a long side surface of the cover and an exterior material are thermally welded.

  In this invention, the opening on the side to which the cover is fitted is such that one end of the exterior material protrudes about the thickness of the cover from the end surface of the battery element, and the heat welding layer is formed on the inside of the exterior portion of the protruding portion. Is preferably provided.

  Further, in this invention, the exterior material is composed of the first and second laminate materials having substantially the same size, and the battery element is accommodated in the recess formed in the first laminate material, and the opening of the recess is formed in the second opening. The first and second laminate materials are overlapped so as to cover the laminate material, the periphery of the opening is sealed, and the electrode terminal lead connected to the battery element is led out from the seal portion, and the concave portion of the first laminate material is It is preferable that the ends of the first and second laminate materials are bonded to each other on the outer side of the bottom surface and the both side surfaces are formed in an elliptical shape that bulges outward.

  As described above, according to the present invention, the cover is provided with recesses on both sides of one long side thereof, and the exterior material is provided with a notch for exposing at least the recesses of the cover. It is possible to provide a battery pack with excellent volume efficiency while adopting a structure for preventing reverse loading of the negative electrode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing a structural example of a battery pack according to an embodiment of the present invention. FIG. 2 is a perspective view showing one shape example of one end of the battery pack according to the embodiment of the present invention. The battery pack is, for example, a battery pack of a lithium ion polymer secondary battery having a square shape or a flat shape, and is housed in the exterior material 1 having both ends opened as shown in FIG. Battery element, and a top cover 2 and a bottom cover 3 respectively fitted to both open ends of the exterior material 1. Hereinafter, the side on which the top cover 2 is fitted is referred to as the top side, and the side on which the bottom cover 3 is fitted is referred to as the bottom side.

  The battery element is, for example, a banknote type battery element having a square shape or a flat shape. The exterior material 1 has a plate shape as a whole, and has a rectangular shape when viewed from the surface direction. The exterior material 1 is provided with notches 10a and 10b so that the recesses 6a and 6b provided on both sides of the long side of the top cover 2 are at least exposed. Moreover, the opening of the both ends of the cladding | exterior_material 1 has a rectangular shape as a whole, and both the short sides swell so that an elliptical arc may be made toward the outer side.

  Further, the top cover 2 and the bottom cover 3 have shapes that can be fitted into the openings at both ends of the exterior material 1. Specifically, when viewed from the front, the top cover 2 and the bottom cover 3 have a rectangular shape as a whole. The side swells outward to form an elliptical arc. As shown in FIG. 2, recesses 6a and 6b for preventing reverse loading of the positive and negative electrodes of the battery pack are provided at both ends of one long side of the top side end surface. Further, through holes 26 a and 26 b are provided on the front surface of the top cover 2.

Hereinafter, the battery element 4, the exterior material 1, the top cover 2, and the bottom cover 3 will be described with reference to FIGS.
<Battery element>
FIG. 3 is a perspective view showing an example of the appearance of the battery element 4 according to the embodiment of the present invention. As shown in FIG. 3, the battery element 4 has, for example, a square shape or a flat shape, and a belt-like positive electrode and a belt-like negative electrode are laminated via a polymer electrolyte and / or a separator and wound in the longitudinal direction. At the same time, electrode leads 5a and 5b 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 positive and negative electrode leads 5a and 5b 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, Li _X MO 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 as a positive electrode active material. Lithium composite oxide mainly composed of 1.10 or less) can be used. As the transition metal M constituting the lithium composite oxide, cobalt (Co), nickel (Ni), manganese (Mn) and the like are preferable.

Specific examples of such a lithium ion composite oxide include LiCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (where 0 <y <1), LiMn ₂ O _{4 and the} like. Can do. 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. Furthermore, as a material capable of doping and dedoping lithium, a polymer such as polyacetylene or polypyrrole or an oxide such as SnO ₂ can be used. When forming the negative electrode from such a material, a binder or the like may be added.

  The polymer electrolyte is made by incorporating a polymer electrolyte, an electrolyte solution, and an electrolyte salt into a polymer into a gel. The polymer material has the property of being compatible with the electrolyte solution, such as silicon gel, acrylic gel, acrylonitrile gel, polyphosphazene modified polymer, polyethylene oxide, polypropylene oxide, and their composite polymer, crosslinked polymer, modified polymer, etc. Alternatively, polymer materials such as poly (vinylidene fluoride), poly (vinylidene fluoride-co-hexafluoropropylene), or poly (vinylidene fluoride-co-trifluoroethylene), and mixtures thereof are used as the fluorine-based polymer. Is 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. Examples of the anion include Cl, Br, I, SCN, ClO4, BF4, PF6, and CF3SO3. 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.

<Exterior material>
FIG. 4 shows a first example of the exterior material 1. As shown in FIG. 4, the exterior material 1 includes a soft laminate 1 a provided with a recess 15 for housing the battery element 4, and a hard layer that is stacked on the soft laminate 1 a so as to cover the recess 15. It consists of a laminate material 1b. For example, the recess 15 is formed according to the shape of the battery element 4 by drawing with a mold in advance. A heat welding sheet 15 a is provided on the outer surface at a position corresponding to the bottom surface of the recess 15.

  The soft laminate 1a has a rectangular shape, and has a top side long side 11a and a bottom side long side 12a having the same length, and a left side short side 13a and a right side short side 14a having the same length. Similarly, the hard laminate 1b is also rectangular, and has a top-side long side 11b and a bottom-side long side 12b having the same length, and a left-side short side 13b and a right-side short side 14b having the same length. The left and right indicate the positional relationship when viewed from the drawing.

  The lengths of the long sides 11b and 12b of the hard laminate 1b are such that the short sides 13b and 14b are in contact with each other or are opposed to each other with a slight gap in a state where the storage portion 15 in which the battery element 4 is stored is wrapped. It is set to be. The lengths of the long sides 11a and 12a of the soft laminate 1a are selected to be shorter than the lengths of the long sides 11b and 12b of the hard laminate 1b. For example, in a state where the storage portion 15 in which the battery element 4 is stored is wrapped. The short sides 13a and 14a are set to contact each other or face each other with a gap. Here, the gap between the soft laminates 1a is not limited to a slight width, and may have a certain width.

  The short sides 13a and 14a of the soft laminate 1a are slightly shorter than the short sides 13b and 14b of the hard laminate 1b. Therefore, the soft laminate material 1a and the hard laminate material 1b can be laminated so that only the hard laminate material 1b exists on the top side. In this case, it is possible to obtain an advantage that the peripheral surface of the top cover 2 provided in the opening on the top side can be thermally welded by the polypropylene layer of the hard laminate 1b. Even on the bottom side, the peripheral surface of the bottom cover 3 provided in the opening on the bottom side can be thermally welded by the polypropylene layer of the hard laminate material 1b so that the adhesive layer of the hard laminate material 1b is exposed. It may be.

  The hard laminate 1b has notches 10a and 10b on one long side thereof. The notches 10a and 10b cover the battery element 4 with the exterior material 1, and when the top cover 2 is fitted in the top opening, the recesses 6a and 6b provided in the top cover 2 are at least exposed. In the position. The notches 10a and 10b are selected to have a shape in which the recesses 6a and 6b of the top cover 2 are at least exposed when the top cover 2 is fitted into the top opening, and have a rectangular shape, for example.

  The soft laminate 1a is suitable for forming the recess 15 into which the battery element 4 is inserted by drawing and is softer than the hard laminate 1b.

  FIG. 5 is a cross-sectional view illustrating a configuration example of the soft laminate material 1 a constituting the exterior material 1. The soft laminate 1a has a laminated structure in which a polypropylene (PP) layer 16a as an adhesive layer, a soft aluminum metal layer 17b as a metal layer, and a nylon layer or PET (polyethylene terephthalate) layer 18a as a surface protective layer are sequentially laminated. The polypropylene layer 16a is on the inner side (the side in contact with the hard laminate 1b).

  The polypropylene layer 16a has a function of preventing deterioration of the polymer electrolyte. For example, non-axially stretched polypropylene (CPP) or the like is used as the polypropylene layer 16a. The thickness of the polypropylene (PP) layer 16a is, for example, about 30 μm.

  The soft aluminum metal layer 17a has a function of preventing moisture from entering the inside. As a material of the soft aluminum metal layer 17a, for example, annealed aluminum (JIS A8021P-O) or (JIS A8079P-O) can be used. Moreover, the thickness of the soft aluminum metal layer 17a is selected in the range of about 30 μm to 130 μm, for example. The nylon layer or PET layer 18a has a function of protecting the surface. The thickness of the nylon layer or the PET layer 18a is selected, for example, in the range of about 10 to 30 μm.

  The hard laminate 1b maintains the shape after bending and can withstand deformation from the outside. The hard laminate 1b has a laminated structure in which a polypropylene layer as an adhesive layer, a hard aluminum metal layer as a metal layer, a nylon layer or a PET layer as a surface protective layer are sequentially laminated.

  The polypropylene layer and the nylon layer or PET layer of the hard laminate 1b are the same as the soft laminate 1a. The hard aluminum metal layer having a thickness in the range of about 30 μm to 130 μm using, for example, aluminum (JIS A3003P-H18) or (JIS A3004P-H18) without annealing treatment is used. In addition, the thickness of each layer of the soft laminate material 1a and the hard laminate material 1b is selected appropriately in consideration of the total thickness.

  FIG. 6 shows a second example of the exterior material 1. In FIG. 6, a laminated battery element 41 for covering with the exterior material 1, and a top cover 2 and a bottom cover 3 provided on both end faces of the laminated battery element 41 are shown.

  The exterior material 1 is a hard laminate material, and has a configuration in which an adhesive layer, a metal layer, and a surface protective layer are sequentially laminated. As a material constituting each layer, for example, the same material as the hard laminate 1b in the first example described above can be used.

  The laminated battery element 41 is obtained by covering the battery element 4 with a soft laminate material so as to lead out the electrode leads 5a and 5b and sealing the periphery thereof by, for example, heat sealing. The soft laminate material is preferably provided with a storage portion for storing the battery element 4, and this storage portion is formed by, for example, drawing the soft laminate material into a predetermined shape in advance using a mold. The soft laminate material has a structure in which an adhesive layer, a metal layer, and a surface protective layer are sequentially laminated. For example, the same material as the soft laminate material 1a in the first example described above is used as the material constituting each layer. be able to.

  The packaging material 1 is rectangular, and has a top-side long side 31a and a bottom-side long side 31b having the same length, and a short side 32a and a short side 32b having the same length. Moreover, the exterior material 1 has the notch parts 10a and 10b in the top side long side 31a side. The notches 10a and 10b cover the battery element 4 with the exterior material 1, and when the top cover 2 is fitted in the top opening, the recesses 6a and 6b provided in the top cover 2 are at least exposed. In the position. The notches 10a and 10b are selected so as to expose at least the recesses 6a and 6b of the top cover 2 when the top cover 2 is fitted into the top opening, and have a rectangular shape, for example.

  The laminated battery element 41 is covered with the exterior material 1 as follows, for example. First, the electrode leads 5 a and 5 b led out from the top side of the laminated battery element 41 are connected to the circuit board accommodated in the top cover 2 and arranged on the end face on the top side of the laminated battery element 41. Next, the laminated battery element 41 is placed on the central portion of the exterior material 1 so that the upper end surface of the top cover 2 is substantially aligned with the top-side long side 31 a of the exterior material 1. Next, the bottom cover 3 is disposed on the end surface on the bottom side of the laminated battery element 41.

  Next, the short side 32a and the short side 32b of the packaging material 1 are bent in the direction in which the laminated battery element 41 is placed, and the surface protective layer of the laminated battery element 41 and the adhesive layer of the packaging material 1 are heated, for example, Bond together by welding. Next, heat welding is performed while holding the entire length with a jig. That is, a heater block made of a metal such as copper is pressed from above and below near the top end of the exterior material 1 to thermally weld the peripheral surface of the top cover 2 and the adhesive layer on the inner surface of the hard laminate 1b. Similarly, the heater block is pressed from above and below near the bottom end of the exterior material 1 so that the peripheral surface of the bottom cover 3 and the adhesive layer on the inner surface of the hard laminate material 1b are thermally welded. Good.

  Next, molten resin is filled between the battery element 4 and the top cover 2 through the through holes 26a and 26b of the top cover 2 and solidified. Next, the molten resin is filled between the battery element 4 and the bottom cover 3 through the through hole of the bottom cover 3 and solidified.

  In addition, after covering the laminated battery element 41 with the exterior material 1 and forming the top side opening and the bottom side opening on both end surfaces of the exterior material 1, the top cover 2 and the bottom side opening respectively. The bottom cover 3 may be fitted.

<Top cover>
FIG. 7 is a perspective view showing a shape example of the top cover 2. The top cover 2 is for closing the opening on the top side. When viewed from the front, the top cover 2 has a rectangular shape as a whole, and both short sides swell outwardly to form an elliptical arc. The top cover 2 has recesses 6a and 6b at corners formed by one long side and both short sides on both sides, respectively. The recesses 6a and 6b are used to prevent reverse loading of the battery pack on the device side in which the battery pack is loaded. The exterior material 1 is provided with notches 10a and 10b at positions opposite to the recesses 6a and 6b, and thus it is possible to make the volume efficiency excellent while taking a structure for preventing the reverse loading of the positive and negative electrodes. it can.

  The shape of the recesses 6a and 6b provided on both sides of the long side of the top cover 2 is not particularly limited, but is preferably a shape that takes into account the degree of design freedom on the device side. It is the shape dented in the step shape toward the direction of 2 short sides.

  Further, the top cover 2 is provided with through holes 26a and 26b penetrating from the surface on the side facing the battery element 4 toward the surface on the opposite side. The number of through holes is not particularly limited, but is, for example, 1 or more, preferably 2 or more. When two or more through holes are provided, at least one through hole can be used for venting air between the battery element 4 and the top cover 2 at the time of resin injection. Can be improved.

  The top cover 2 is provided with a circuit board, and electrode leads 5a and 5b drawn from the battery element 4 are connected to the circuit board.

  The circuit board is mounted with a protection circuit including a temperature protection element such as a fuse, PTC, and thermistor, an ID resistor for identifying the battery pack, and a plurality of, for example, three contact portions. Further, the protection circuit includes an IC for monitoring the secondary battery and controlling an FET (Field Effect Transistor), and a charge / discharge control FET.

  The PTC is connected in series with the battery element 4, and when the temperature of the battery element 4 becomes higher than the set temperature, the electrical resistance increases rapidly and substantially blocks the current flowing through the battery. A fuse and a thermistor are also connected in series with the battery element 4, and when the temperature of the battery element 4 becomes higher than the set temperature, the current flowing through the battery is cut off. Further, the protection circuit including the IC for monitoring the battery element 4 and controlling the FET and the charge / discharge control FET is dangerous if the terminal voltage of the battery element 4 exceeds 4.3V to 4.4V. Therefore, the voltage of the battery element 4 is monitored, and if it exceeds 4.3 to 4.4 V, the charge control FET is turned off and charging is prohibited. When the terminal voltage of the battery element 4 is overdischarged to below the discharge prohibition voltage and the secondary battery voltage becomes 0V, the battery element 4 may be in an internal short circuit state and may not be recharged. If the voltage falls below the discharge inhibition voltage, the discharge control FET is turned off to inhibit discharge.

<Bottom cover>
The bottom cover 3 closes the opening on the bottom side. When viewed from the front direction, the bottom cover 3 has a rectangular shape as a whole, and bulges so that both sides on the short side form an elliptical arc toward the outside. Yes. A side wall for fitting into the bottom side opening is provided on the surface of the bottom cover 3 on the battery element 4 side. The side wall is provided along part or all of the outer periphery of the bottom cover 3. Further, the side wall is provided at a position slightly inward from the outer periphery of the bottom cover 3, for example, at a position inward from the outer periphery of the bottom cover 3 by an amount corresponding to the thickness of the exterior material 1.

  Further, the bottom cover 3 is provided with one or more, preferably two or more through holes penetrating from the surface on the side facing the battery element 4 toward the surface on the opposite side. When two or more through holes are provided, at least one through hole can be used for venting air between the battery element 4 and the bottom cover 3 at the time of resin injection. Can be improved.

  Next, a method for manufacturing a battery pack according to an embodiment of the present invention will be described.

<Battery element manufacturing process>
First, for example, a positive electrode and a negative electrode each having a gel electrolyte layer formed on both sides, and a separator are sequentially laminated in the order of the negative electrode, the separator, the positive electrode, and the separator, and this laminate is wound around a flat plate core, A wound battery element 4 is produced by winding.

<Exterior material coating process>
Next, the concave portion 15 for inserting the battery element 4 is formed in the soft laminate 1a in advance by, for example, deep drawing. At this time, as shown in FIG. 4A, the battery element housing recess 15 of the soft laminate material 1a is formed, for example, at a position slightly shifted to the right side with respect to the center position. And the battery element 4 is accommodated in the recessed part 15 formed in the soft laminate material 1a.

  Next, as shown in FIG. 4A, the hard laminate material 1b is laminated at a position slightly shifted to the right side with respect to the soft laminate material 1a. Thereby, in the state where the soft laminate material 1a and the hard laminate material 1b are laminated, as shown in FIG. 4A, the left region where only the soft laminate material 1a is located and the right region where only the hard laminate material 1b is located Arise. As described later, the positions are shifted in this way after the ends of the soft laminate 1a and the hard laminate 1b are folded toward the outside of the bottom surface of the recess 15 of the soft laminate 1a, and then the soft laminate 1a This is because the polypropylene layer and the polypropylene layer of the hard laminate 1b are bonded with a certain width.

  Next, in the state of arrangement as shown in FIG. 4A, heat welding is performed while reducing the four sides around the opening of the recess 15. In this case, the entire portion where the polypropylene layers overlap may be heat-welded. In this way, the battery element 4 is sealed by thermally welding the periphery of the recess 15.

  Next, as shown in FIG. 4A, a heat welding sheet 15 a having a predetermined shape is provided outside the bottom surface of the recess 15. The heat welding sheet 15a is an auxiliary member for bonding the nylon layer or the PET layer of the soft laminate 1a by applying a high temperature. Preferably, the thickness is about 10 to 60 μm in relation to the total thickness, and a melting point of about 100 ° C. is used. The melting point of the heat welding sheet 15a is preferably such that the battery element 4 is not affected by heat.

  Next, as shown in FIG. 8, both ends of the soft laminate material 1a and the hard laminate material 1b, that is, the short sides 13a, 14a and 13b, 14b are directed inward toward the bottom surface outside the concave portion 15 of the soft laminate material 1a. Fold it in. Then, the end portions of the soft laminate material 1 a and the hard laminate material 1 b are heat welded, and the soft laminate material 1 a is heat welded to the outside of the bottom surface of the recess 15. Thereby, the soft laminate material 1a and the hard laminate material 1b are fixed in a closed state so as to wrap around the recess 15 in which the battery element 4 is accommodated, so that a top side opening and a bottom side opening are formed.

  As shown in FIG. 9, in a state where the battery element 4 is wrapped, the short side 13b and 14b of the hard laminate material 1b are in contact with each other, or the seam L1 formed by facing the end faces through a slight gap is formed. In addition, the short side 13a and 14a of the soft laminating material 1a are in contact with each other inside the hard laminating material 1b, or a seam L2 is formed in which the end faces are opposed to each other through a slight gap. In FIG. 7, reference numeral 16b indicates a polypropylene layer of the hard laminate material 1b, reference numeral 17b indicates a hard aluminum metal layer, and reference numeral 18b indicates a nylon layer or a PET layer. Here, the case where the short sides 13a and 14a of the soft laminate 1a are in contact with each other, or the end surfaces of each other face each other with a slight gap is illustrated and described. Thus, the end surfaces may be opposed to each other.

  As shown in FIG. 9, the nylon layer or the PET layer 18a of the soft laminate 1a is located in contact with the upper side of the heat welding sheet 15a. Accordingly, the nylon layer or the PET layer 18a has a structure in which the heat welding sheet 15a is sandwiched, and the nylon layer or the PET layer 18a can be bonded to each other by applying heat from the outside. Further, since the polypropylene layers 16a and 16b of the soft laminate material 1a and the hard laminate material 1b face each other, these polypropylene layers 16a and 16b can be bonded by applying heat from the outside.

  As described above, it is possible to manufacture a battery pack in which the laminate material also serves as an exterior material without using a resin box-shaped case and without arranging resin frames on both sides.

<Top cover mating process>
Next, as shown in FIG. 10, the electrode leads 5a and 5b are connected to the circuit board 22 by, for example, resistance welding or ultrasonic welding. Next, as shown in FIG. 11, the circuit board 22 is inserted into the open surface side of the top cover 2, and the top cover 2 is attached to the circuit board 22 so as to cover the circuit board 22. The top cover 2 is, for example, a resin molded product manufactured by injection molding or the like in a separate process.

  Note that a holding portion that holds the circuit board 22 horizontally is provided inside the top cover 2. Further, three openings 21 are provided on the top cover 2 at positions corresponding to the contact portions 23 of the circuit board 22. The contact portion 23 faces the outside through the opening 21. The width of the top cover 2 is selected to be slightly smaller than the inner dimension of the height of the opening on the end surface on the top side of the exterior material 1.

  Next, as shown in FIG. 12, the holder 24 is assembled to the top cover 2. The holder 24 is a resin molded product manufactured by, for example, injection molding in a separate process. Ribs 25a, 25b, and 25c that protrude toward the top cover 2 are provided at both ends and the center of the holder 24, respectively. Since the end surfaces of these ribs 25a, 25b and 25c serve as surfaces for receiving the circuit board 22 in the top cover 2, the circuit board 4 can be reliably supported.

  Next, as shown by an arrow R in FIG. 13, the fitted top cover 2 and holder 24 are rotated 90 ° clockwise by hand or a jig. As a result, the circuit board 22 that has been positioned horizontally is positioned vertically. In this case, since the circuit board 22 is sandwiched between the top cover 2 and the holder 24 and is not exposed to the outside, it can be rotated without touching the circuit board 4.

Next, as shown in FIG. 14, pushed the top cover 2 and the holder 24 while bending the electrode lead 5a and 5b toward the top-side opening (the direction of arrow S _1). Thereby, the top cover 2 and the holder 24 are fitted to the top side opening. Since the width of the top cover 2 is slightly smaller than the inner dimension of the opening as described above, the circuit board 22 is sandwiched in the space formed by the hard laminate 1b near the end face of the exterior material 1. The top cover 2 and the holder 24 can be stored.

<Bottom cover fitting process>
Next, as shown in FIG. 14, the side wall of the bottom cover 3 is pushed toward the opening on the bottom side end face of the exterior material 1 (in the direction of the arrow S ₂ ). Thereby, the side wall of the bottom cover 3 is fitted to the bottom side opening, and the bottom side opening is covered by the main body of the bottom cover 3. The bottom cover 3 is, for example, a resin molded product manufactured by injection molding in a separate process.

<Heat welding process>
Next, heat welding is performed while holding the entire length with a jig. That is, a heater block made of a metal such as copper is pressed from above and below near the top end of the exterior material 1 to thermally weld the peripheral surface of the top cover 2 and the polypropylene layer on the inner surface of the hard laminate 1b. Similarly, the heater block is pressed near the bottom end of the exterior material 1 from above and below to thermally weld the peripheral surface of the bottom cover 3 and the polypropylene layer on the inner surface of the hard laminate 1b. Good.

<Resin injection process>
Next, molten resin is filled between the battery element 4 and the top cover 2 through the through holes 26a and 26b of the top cover 2 and solidified. Thereby, the top cover 2 is bonded to the end face of the battery element 4.

Next, the molten resin is filled between the battery element 4 and the bottom cover 3 through the through hole of the bottom cover 3 and solidified. Thereby, the bottom cover 3 is bonded to the end face of the battery element 4. The resin to be filled is not particularly limited as long as it has a low viscosity state at the time of casting, and for example, polyamide hot melt, polyolefin hot melt, nylon, PP, PC, ABS or the like is used. be able to.
The battery pack according to one embodiment of the present invention is manufactured through the above steps.

According to one embodiment of the present invention, the following effects can be obtained.
The battery pack includes a rectangular or rectangular exterior material 1 with both ends open, a battery element 4 accommodated in the exterior material 1, and a top cover 2 fitted to both open ends of the exterior material 1. And a bottom cover 3. The top cover 2 is provided with recesses 6a and 6b on both sides of one long side thereof, and the exterior material 1 is provided with notches 10a and 10b for exposing at least the recesses 6a and 6b of the top cover 2. Thereby, reverse loading of the positive and negative electrodes can be prevented without causing a decrease in volumetric efficiency.

  Further, when the exterior material 1 formed by superposing the hard laminate material 1b on the soft laminate material 1a is used, the short sides 13a and 14a of the soft laminate material 1a are connected to the short sides 13b and 14b of the hard laminate material 1b. The top cover 2 is positioned and fitted on the short side, and the long side is laminated by laminating the soft laminate 1a and the hard laminate 1b so that only the hard laminate 1b exists on the top side. The peripheral surface of the top cover 2 fitted on the side can be thermally welded by the polypropylene layer of the hard laminate 1b.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples. Hereinafter, examples and comparative examples of the present invention will be described in detail with reference to the drawings.

EXAMPLE FIG. 15 is a perspective view showing the external shape of the battery pack of the example. The top cover 2 is provided with recesses 6a and 6b at both ends of one long side of the end surface, and the exterior material 1 is provided with notches 10a and 10b for exposing the recesses 6a and 6b of the top cover 2.

Comparative Example 1
FIG. 16 is a perspective view showing the external shape of the battery pack of Comparative Example 1. FIG. Except for omitting the formation of the cutout portions 10a and 10b with respect to the exterior material 1, all the processes were the same as in the example.

Comparative Example 2
FIG. 17 is a perspective view showing the external shape of the battery pack of Comparative Example 2. Instead of providing the recesses 6a and 6b of the top cover 2 and the notches 10a and 10b of the exterior material 1, projections 101a and 101b are provided on the top end surface of the battery pack to determine the direction of the positive and negative electrodes. Except for the above, all of the examples were the same as in the example.

Comparative Example 3
FIG. 18 is a perspective view showing the external shape of the battery pack of Comparative Example 3. Instead of providing the cutouts 10 a and 10 b in the exterior material 1, the end surface of the top cover 2 protrudes from the opening on the top side of the exterior material 1 so that the recesses 6 a and 6 b of the top cover 2 are not covered with the exterior material 1. Except for the above, everything was the same as in the example.

  The following can be understood by comparing the above-described Examples and Comparative Examples.

  In Comparative Example 1, since the entire peripheral surface of the top cover 2 is covered with the exterior material 1, there is no degree of freedom in designing the protrusions that fit into the recesses 6a and 6b on the device side. Moreover, when the exterior material 1 of the part covering the recesses 6a and 6b is dented into the recesses 6a and 6b due to an external impact such as dropping, it is expected that a problem occurs in loading into the device.

  Further, in Comparative Example 2, the direction of the positive and negative electrodes can be determined by the protrusions 101a and 101b provided on the top side end face. However, in this case, the outer dimensions of the battery pack are increased. Moreover, it is necessary to make the shape of the protrusions 101a and 101b match the shape on the device side, and the versatility is poor. Furthermore, if the protrusions 101a and 101b are damaged by an external impact such as dropping, the positive / negative polarity direction may not be discriminated.

  Further, in Comparative Example 3, it is necessary to increase the height of the top cover 2 itself in order to sufficiently take the heat fusion allowance between the top cover 2 and the exterior material 1, and the volume efficiency of the battery pack cannot be increased. End up.

  In contrast, in the embodiment, the top cover 2 is provided with recesses 6a and 6b on both sides of one long side thereof, and the exterior material 1 is provided with a notch for exposing at least the recesses 6a and 6b of the top cover 2. Since the parts 10a and 10b are provided, there is no problem as in Comparative Examples 1 to 3. That is, in the embodiment, advantages such as no reduction in volumetric efficiency, no deformation of the exterior material 1 due to an external impact such as dropping, excellent versatility, and excellent volumetric efficiency can be obtained.

  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, the numerical values given in the above-described embodiment are merely examples, and different numerical values may be used as necessary.

It is a disassembled perspective view which shows the example of 1 structure of the battery pack by one Embodiment of this invention. It is a perspective view which shows one shape example of the end of the battery pack by one Embodiment of this invention. It is a perspective view which shows an example of the external appearance of the battery element by one Embodiment of this invention. It is an expanded view which shows the 1st example of an exterior material. It is sectional drawing which shows one structural example of the soft laminate material which comprises an exterior material. It is a perspective view which shows the 2nd example of an exterior material. It is a perspective view which shows one example of a shape of a top cover. It is a perspective view which shows an example of the external appearance of the battery element coat | covered with the exterior material. It is an expanded sectional view of the exterior material which coat | covered the battery element. It is a perspective view for demonstrating the manufacturing method of the battery pack by one Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by one Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by one Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by one Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by one Embodiment of this invention. It is a perspective view which shows the external appearance shape of the battery pack of an Example. 6 is a perspective view showing an external shape of a battery pack of Comparative Example 1. FIG. 10 is a perspective view showing an external shape of a battery pack of Comparative Example 2. FIG. 10 is a perspective view showing an external shape of a battery pack of Comparative Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior material 1a Soft laminating material 1b Hard laminating material 2 Top cover 3 Bottom cover 4 Battery element 5a, 5b Electrode lead 6a, 6b Recessed part 10a, 10b Notch

Claims (3)

A rectangular or flat battery element is housed in a hard exterior material having openings at both ends, and a cover manufactured by resin molding is fitted into at least one opening from which the electrode terminal lead is led out. In a rectangular or flat battery pack in which a circuit board to be joined to the electrode terminal lead of the battery element is housed in the cover fitted in the opening of the battery,
The cover has recesses on both sides of one long side,
The exterior material has a notch for exposing at least the concave portion of the cover,
A battery pack, wherein at least the side surface of the long side of the cover and the exterior material are heat-welded. The opening on the side where the cover is fitted is such that one end of the exterior material protrudes from the end surface of the battery element by the thickness of the cover,
The battery pack according to claim 1, wherein a heat welding layer is provided on the inner side of the projecting portion of the exterior material. The exterior material is composed of first and second laminate materials having substantially the same size,
The battery element is housed in a recess formed in the first laminate material, and the first and second laminate materials are stacked so that the opening of the recess is covered by the second laminate material, and the periphery of the opening And electrode terminal leads connected to the battery element are led out from the seal portion, and the end portions of the first and second laminate materials are outside the bottom surface of the concave portion of the first laminate material. The battery pack according to claim 1, wherein the battery pack is formed into an oval shape that is bonded and has both side surfaces bulging outward.

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