JP2010165646A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack capable of enhancing insulation reliability and yet improving the efficiency of production. <P>SOLUTION: A first holder 23 is housed in a top cover 2 so as to cover a circuit board 21, and the circuit board 21 is pinched by the top cover 2 and the first holder 23 opposed to the top cover 2. A safety protection element 27 is arranged between the first holder 23 and a second holder 24 opposed to the first holder 23, and is pinched by the first holder 23 and the second holder 24 opposed to the first holder 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a battery pack. More specifically, for example, the present invention relates to a battery pack of a lithium ion secondary battery.

  In recent years, portable electronic devices such as notebook PCs (Personal Computers), mobile phones, and PDAs (Personal Digital Assistants) have become widespread, and lithium-ion secondary batteries having advantages such as high voltage, high energy density, and light weight as power sources. in use. This lithium ion secondary battery is widely used as a battery pack that is covered with an exterior film and added with a circuit such as a protective circuit. For example, Patent Document 1 proposes a battery pack in which a battery element is accommodated in an exterior film having an open end surface and a circuit board is assembled.

JP 2005-166650 A

  When assembling such a battery pack, contact between circuit boards, tabs, electrical and connection parts such as PTC (Positive Temperature Coefficient), and cell components such as cell laminate and cell lead, or cell leads and cell laminates There is a risk of contact. Thereby, it may lead to defects, such as an output defect as a battery pack, a characteristic defect typified by an impedance defect (Imp defect), and swelling due to aluminate alloying.

  The battery pack described in Patent Literature 1 has a structure in which a top cover is provided on an end surface on the top side of the battery pack, and a circuit board is accommodated in the top cover. FIG. 27 is a cross-sectional view for explaining the process of incorporating the top cover.

  In FIG. 27, the circuit board 202 is accommodated in the top cover 201 of the battery pack 208. A lead 204 led out from the battery cell 203 is joined to the circuit board 202. The holder 205 is disposed so as to cover the circuit board 202 bonded to the battery cell 203.

  With the circuit board 202 and the holder 205 assembled in the top cover 201, the top cover 201 is accommodated in the space of the top portion of the battery pack 208. The top cover 201 is accommodated in the space of the top portion of the battery pack 208 after the 90 ° C. lead 204 is bent as indicated by an arrow S and then the lead 204 is further bent.

  FIG. 28 shows a state where the top cover 201 is accommodated in the space of the top portion. As shown in FIG. 28, the battery pack 208 has a structure in which a circuit board 202 and a holder 205 are incorporated in a top cover 201 and incorporated in a space provided at an end portion on the top side of the battery pack 208. However, since there is very little space between the battery cell 203 and parts such as the circuit board 202 and the holder 205, a contact problem between the metal part and the cell part is likely to occur.

  In order to avoid such a contact problem, conventionally, as shown in FIGS. 29A and 29B, a conductive member such as a tab provided on the circuit board 202 or a metal such as a lead 204 led out from the battery cell 203 is exposed. The insulating member 210 was manually pasted at the location. The insulating member 210 is, for example, an insulating tape cut or a componentized insulating tape. Depending on the structure, shape, assembly method, and the like of the battery pack, a plurality of insulating members 210 to be attached may be required.

  However, when the insulating member 210 is used, the insulating member 210 having a sufficient size and shape is attached to the object to be insulated, but there is a problem that the insulation may not be sufficiently performed due to variations in work. . In other words, an insulation failure occurs due to a shift in the attaching position of the insulating member 210, and thus there is a problem that the insulation may not be sufficiently performed depending on work accuracy.

  In addition, when a plurality of insulating members 210 are required, the volume of the insulating member 210 increases, so that the top cover 201 cannot be stored in the space of the top portion, resulting in a problem of dimensional defect of the battery pack. There was a risk of it. Furthermore, when a plurality of insulating members 210 are required, there is a problem in that the production efficiency decreases because the number of attaching steps increases as the number of insulating members 210 increases.

  Accordingly, an object of the present invention is to provide a battery pack that can improve the reliability of insulation and improve the production efficiency.

  In order to solve the above-described problems, the present invention provides a battery element, an exterior material in which the battery element is accommodated, a cover that closes the opening of the exterior material, and the battery element that is connected to the battery element by a conductive member. A battery pack comprising a circuit board, a first holder accommodated in a cover facing the circuit board, and a second holder accommodated in the cover facing the first holder and covering the conductive member.

  In this invention, since it has the 2nd holder accommodated in a cover facing the 1st holder and covering a conduction | electrical_connection member, the reliability of insulation can be improved and production efficiency can be improved.

  According to this invention, the reliability of insulation can be improved and the production efficiency can be improved.

It is a perspective view which shows the external appearance of the battery pack by 1st Embodiment of this invention. It is a perspective view which shows the structure of a battery element. It is an expanded view for demonstrating the structure of an exterior material. It is sectional drawing which shows the structure of a hard laminate material and a soft laminate material. It is a disassembled perspective view which shows the structure of the top cover assembly of the battery pack by 1st Embodiment of this invention. It is a perspective view which shows the state which integrated the 1st holder in the top cover. It is a perspective view which shows the state which integrated the 1st holder and the 2nd holder in the top cover. It is a disassembled perspective view which shows the structure of the top cover assembly of the conventional battery pack. It is a perspective view for demonstrating the manufacturing method of the battery pack by 1st Embodiment of this invention. It is sectional drawing for demonstrating the manufacturing method of the battery pack by 1st Embodiment of this invention. It is a sequence diagram for demonstrating the fitting process of a top cover simply. It is a perspective view for demonstrating the fitting process of a top cover. It is a perspective view for demonstrating the fitting process of a top cover. It is a perspective view for demonstrating the fitting process of a top cover. It is a perspective view for demonstrating the fitting process of a top cover. It is a perspective view for demonstrating the fitting process of a top cover and a bottom cover. It is a perspective view which shows the external appearance of the battery pack by 2nd Embodiment of this invention. It is an exploded view which shows the structure of the battery pack by 2nd Embodiment of this invention. It is sectional drawing which shows the structure of a hard laminate material. It is a perspective view for demonstrating the manufacturing method of the battery pack by 2nd Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by 2nd Embodiment of this invention. It is a perspective view for demonstrating the manufacturing method of the battery pack by 2nd Embodiment of this invention. It is a schematic diagram for demonstrating an Example. It is a schematic diagram for demonstrating an Example. 6 is a graph showing the results of Comparative Example 1. 3 is a graph showing the results of Example 1. Sectional drawing for demonstrating the incorporating process of a top cover is shown. It is sectional drawing which shows the state in which the top cover assembly was accommodated in the space of the top part. It is a schematic diagram for demonstrating the conventional insulation method.

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless stated to the effect, the present invention is not limited to the embodiment. The description will be given in the following order.
1. First embodiment (first example of battery pack)
2. Second embodiment (second example of battery pack)
3. Other Embodiment (Modification of Battery Pack)

1. First embodiment (first example of battery pack)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration example of a battery pack according to the first embodiment of the present invention. This battery pack is a battery pack of a lithium ion secondary battery having, for example, a square shape or a flat shape.

  As shown in FIG. 1, in this battery pack, a battery element is housed in an exterior material 1, and a top cover 2 and a bottom cover 3 are fitted into openings at both ends, respectively. The top cover 2 is provided with a plurality of openings 17 through which the contact portions of the circuit board accommodated in the top cover 2 face the outside. Hereinafter, the opening on the side where the top cover 2 is fitted is referred to as a top side opening, and the opening on the side where the bottom cover 3 is fitted is referred to as a bottom side opening.

  Hereinafter, the battery element, the exterior material 1, the top cover 2, and the bottom cover 3 will be sequentially described.

<Battery element>
FIG. 2 is a perspective view showing an example of the external appearance of the battery element. As shown in FIG. 2, 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. The electrode lead 5a is led out from the positive electrode. The electrode lead 5b is led out from the negative electrode. 3. As will be described later in another embodiment, the configuration of the battery element 4 is not limited to this.

  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 an 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 case of constituting the lithium ion battery, in Li _X MO ₂ (wherein as a positive electrode active material, M represents one or more transition metals, X is vary according to charge and discharge state of the battery, usually 0.05 or more 1 Lithium composite oxide mainly composed of .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 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, 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. 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.

<Exterior material>
FIG. 3 is a development view showing an example of the shape of the exterior material 1 that covers the battery element 4. As shown in FIG. 3, the exterior material 1 includes a soft laminate 1 a provided with a storage portion 15 for storing the battery element 4, and a soft laminate material 1 a overlaid on the soft laminate material 1 a so as to cover the storage portion 15. Hard laminate material 1b. A heat welding sheet 15 a is disposed on the outer surface at a position corresponding to the bottom surface of the storage unit 15. The storage portion 15 provided in the soft laminate 1 a is formed in a concave shape in accordance with the shape of the battery element 4 by, for example, drawing in advance with a mold.

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

  FIG. 4A is a cross-sectional view illustrating a configuration example of the soft laminate material 1 a that constitutes the exterior material 1. The soft laminate 1a has a moisture-proof and insulating laminated structure in which an adhesive layer 16a, a metal layer 17a, and a surface protective layer 18a are sequentially laminated, and the surface protective layer 18a comes into contact with the hard laminate.

  The adhesive layer 16a has a function of preventing the deterioration of the polymer electrolyte, and is a portion that is melted by heat or ultrasonic waves and fused to each other, and includes polyethylene (PE), non-axially stretched polypropylene (CPP), polyethylene terephthalate (PET), In addition to nylon (Ny), low density polyethylene (LDPE), high density polyethylene (HDPE), and linear low density polyethylene (LLDPE) can be used, and a plurality of types can be selected and used. The thickness of the adhesive layer 16a is, for example, about 30 μm.

  The metal layer 17a is made of a soft metal material and plays a role of protecting the contents by preventing the entry of moisture, oxygen and light in addition to improving the strength of the exterior material. As the soft metal material, aluminum is most preferable from the viewpoint of lightness, extensibility, price, and ease of processing, and it is particularly preferable to use aluminum such as 8021O or 8079O based on JIS standards. Moreover, the thickness of the metal layer 17a is selected in the range of about 30 μm to 130 μm, for example.

  The surface protective layer 18a has a surface protective function. Polyolefin resins, polyamide resins, polyimide resins, polyesters and the like are used because of their beautiful appearance, toughness, and flexibility. Specifically, nylon (Ny), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN) are used. Is also possible. The thickness of the surface protective layer 18a is selected, for example, in a range of about 10 to 30 μm.

  FIG. 4B is a cross-sectional view illustrating a configuration example of the hard laminate material 1b. 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 an adhesive layer 16b, a metal layer 17b, and a surface protective layer 18b are sequentially laminated.

  The adhesive layer 16b and the surface protective layer 18b of the hard laminate 1b are the same as the soft laminate 1a. For example, a hard metal material is used for the metal layer 17b, and it is particularly preferable to use aluminum based on JIS standards such as 3003H18 and 3004H18. 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.

  The hard laminate material 1b is placed on the soft laminate material 1a so as to cover the opening surface of the storage unit 15. In this case, as shown in FIG. 3A, the positional relationship between the soft laminate material 1a and the hard laminate material 1b is shifted. Here, the soft laminate 1a has a top side long side 11a and a bottom side long side 12a having the same length, and has a left side short side 13a and a right side short side 14a having the same length. Similarly, the hard laminate 1b has a top-side long side 11b and a bottom-side long side 12b having the same length, and has 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 in contact with each other or are set to 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 adhesive layer of the hard laminate material 16b is exposed so that 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. It may be.

<Top cover assembly>
The top cover 2 is fitted into the top side opening of the exterior material 1 and closes the top side opening. The top cover 2 accommodates a circuit board, a safety protection element, and the like. Hereinafter, in the present specification, for convenience of explanation, the top cover 2 and the parts assembled in the top cover 2 are collectively referred to as a top cover assembly.

  FIG. 5 is an exploded perspective view showing the configuration of the top cover assembly. The top cover 2 accommodates a circuit board 21, and electrode leads 5 a and 5 b (not shown in FIG. 5) drawn from the battery element 4 with respect to tabs 22 a and 22 b provided on the circuit board 21, respectively. Connected.

  A first holder 23 is accommodated in the top cover 2 so as to cover the circuit board 21, and the circuit board 21 is sandwiched between the top cover 2 and the first holder 23 facing the top cover 2. The safety protection element 27 is disposed between the first holder 23 and the second holder 24 facing the first holder 23, and the first holder 23 and the second holder facing the first holder 23. It is clamped by the holder 24. The safety protection element 27 is connected to the electrode lead 5b.

<Top cover>
The top cover 2 is a resin molded cover provided on the end surface on the top side of the battery pack. The top cover 2 is fitted into an opening of a battery cell formed by wrapping the battery element 4 with the exterior material 1 and is bonded to the battery cell by heat fusion or the like. In the present specification, for convenience of explanation, the battery element 4 that is wrapped with an exterior material and not connected to the circuit board is referred to as a battery cell. Two shafts 31 a to 31 b extending in a direction facing the first holder 23 (direction shown by an arrow P) are provided at both ends of the surface of the top cover 2 facing the circuit board 21. .

  The two shafts 31 a to 31 b are, for example, cylindrical and are inserted into two positioning holes 32 a to 32 b provided at both ends of the first holder 23. The two shafts 31 a to 31 b are inserted into two holes 37 a to 37 b provided at both ends of the second holder 24.

  Moreover, the battery cell and the side walls 33a-33b for fitting are formed in the both ends of the top cover 2. As shown in FIG. Furthermore, a plurality of locking holes 34 that are used when fitting the first holder 23 are provided on the surface of the top cover 2 that protrudes toward the first holder 23 in the longitudinal direction.

<First holder>
The first holder 23 is a resin molded part that fits with the top cover 2 and fixes the circuit board 21 provided between the first holder 23 and the top cover 2 to the top cover 2. At both ends of the first holder 23, two positioning holes 32 a to 32 b that penetrate in a direction facing the top cover 2 are provided.

  When the first holder 23 and the top cover 2 are fitted, the two shafts 31a to 31b of the top cover 2 are inserted into the holes 32a to 32b, respectively. In the longitudinal direction of the first holder 23, two notches 35a to 35b having widths through which the tabs 22a to 22b can pass are provided at positions facing the tabs 22a to 22b.

  Furthermore, the width of the two cutout portions 35a to 35b is larger than the width of the plate-like protruding portion of the second holder described later. Further, the first holder 23 is provided with a plurality of hooks 36 used when fitting with the top cover 2. The hook 36 is provided on a surface that is located near the center of the first holder 23 in the longitudinal direction and protrudes in a direction facing the top cover 2 side.

  FIG. 6 is a perspective view showing a state in which the first holder 23 and the top cover 2 are fitted. Normally, the top cover 22 and the first holder 23 are fitted with the battery cell electrode leads 5 a and 5 b connected to the tabs 22 a to 22 b of the circuit board 21. Here, in order to simplify the description, the circuit board 21 will be described in a state where the electrode leads 5a and 5b are not connected.

  The circuit board 21 is accommodated from the open surface side of the top cover 2, and the first holder 23 and the top cover 2 are fitted so as to cover the circuit board 21. The circuit board 21 is disposed between the top cover 2 and the first holder 23. The first holder 23 has a function to insulate the mounting parts of the circuit board 21 and the conductive parts such as the safety protection element 27 and the electrode leads 5a and 5b.

  Each of the two shafts 31a to 31b of the top cover 2 is inserted into the positioning holes 32a to 32b of the first holder, respectively. The top cover 2 and the first holder 23 are engaged with each other by the hook 36 provided in the first holder 23 entering the hole 34 for locking the top cover 2.

  The two tabs 22 a to 22 b of the circuit board 21 are extended in a direction facing the first holder 23, and pass through the notches 35 a to 35 b of the first holder 23. Electrode leads 5a and 5b (not shown in the figure) are connected to the two tabs 22a to 22b, respectively. The first holder 23 is disposed to face the circuit board 21, and fixes the circuit board 21 by pressing the circuit board 212 on the facing surface.

<Circuit board>
The circuit board 21 includes a charge / discharge FET (Field Effect Transistor), a protection circuit including an IC (Integrated Circuit) for monitoring the secondary battery and controlling the charge / discharge control FET, an ID resistor for identifying the battery pack, A connector or the like for connecting to the outside is mounted. The circuit board 21 is provided with, for example, three contact portions.

  The protection circuit including the IC that controls the charge / discharge control FET and the charge / discharge control FET monitors the voltage of the secondary battery, and when the voltage exceeds 4.3V to 4.4V, the charge / discharge control FET is turned off and charging is prohibited. To do. Furthermore, when the terminal voltage of the secondary battery is over-discharged to the discharge prohibition voltage or lower and the secondary battery voltage falls below the discharge prohibition voltage, the discharge control FET is turned off and discharge is prohibited.

<Safety protection element>
The safety protection element 27 is a part that cuts off the current circuit of the battery and prevents thermal runaway of the battery cell when the battery becomes hot, and is, for example, a PTC element, a fuse, or a thermistor. The PTC element is connected in series with the battery cell, and when the temperature of the battery 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, and when the temperature of the battery becomes higher than the set temperature, the current flowing through the battery is cut off.

<Second holder>
The second holder 24 is stored in the top cover 2 so as to face the first holder 23. The second holder 24 is a resin molded part that fits into the top cover 2. A safety protection element 27 is disposed between the first holder 23 and the second holder 24. The electrode leads 5a to 5b, which are conductive members that conduct the circuit board 21 and the battery cell, the tabs 22a to 22b connected to the electrode leads 5a to 5b, and the safety protection element 27 are covered with the second holder 24. . Thereby, the electrode leads 5a to 5b, the tabs 22a to 22b, the safety protection element 27, and the battery cell can be reliably insulated. The second holder 24 has plate-like projecting portions 39 a to 39 b extending in a direction facing the first holder 23.

  FIG. 7 is a perspective view showing a state in which the second holder 24 is accommodated in the top cover 2. The second holder 24 is accommodated in the top cover 2 so as to cover the first holder 23. The two shafts 31 a to 31 b of the top cover 2 are respectively inserted into the two positioning holes 37 a to 37 b of the second holder 24, and the second holder 24 is incorporated into the top cover 2.

  The plate-like protrusions 39 a to 39 b of the second holder 24 have a width smaller than the width of the notch 35, and the notches 35 a to 35 b in the state where the second holder 24 is incorporated in the top cover 2. Then, the exposed portions of the tabs 22 a to 22 b on the upper surface side of the top cover 2 and the exposed portions of the safety protection element 27 are covered. Thereby, insulation can be performed reliably.

  Further, in a state where the top cover assembly is housed in the battery cell, the second holder 24 faces the end surface of the battery cell (not shown in FIG. 7), and is on the side of the second holder 24 facing the battery cell. The surface and the end surface of the battery cell contact each other at the surface. Thereby, the 2nd holder 24 is pressed in the direction which opposes a 1st holder. The second holder 24 and the opposing surfaces of the first holder are in contact with each other, and the pressing force from the battery cell surface is evenly transmitted to the first holder 23 via the second holder 24. Thereby, fixation of the circuit board 21 is stabilized more.

  Thus, the 2nd holder 24 has a function which insulates conduction parts, such as safety protection element 27 and tabs 22a-22b, and a battery cell. In addition, the back-up force by the electronic cell is evenly transmitted to the first holder 23, and the circuit board 21 is fixed more firmly.

<Difference from conventional structure>
Here, in order to facilitate understanding of the present invention, a configuration example of the conventional top cover assembly is given, and the configuration of the conventional top cover assembly and the configuration of the top cover assembly of the battery pack of the first embodiment are described. Describe the differences.

  FIG. 8 is an exploded perspective view showing a configuration of a conventional top cover assembly. A conventional top cover assembly includes a top cover 301, a circuit board 302, tabs 303 a to 303 b, a PTC element 305, an insulating tape 306, and a holder 307.

  The insulating tape 306 is affixed to a portion where the conductive member such as the tabs 303a to 303b is exposed or the PTC element 305, thereby insulating the battery cell or the like. A circuit board 302 is disposed between the top cover 301 and the holder 307. The holder 307 and the top cover 301 are fitted.

  In the conventional top cover assembly having the configuration shown in FIG. 8, there is one holder 307 accommodated in the top cover 301, and insulation is performed by disposing an insulating tape 306 in a portion where the conductive member is exposed. It was.

  However, the configuration shown in FIG. 8 has the following problems. There is a risk that an insulation failure may occur due to the misalignment of the insulating tape 306. Since the insulating tape 306 is affixed manually, many insulation defects occur depending on the variation of the work. Moreover, since it is necessary to stick the some insulating tape 306 correctly, production efficiency is bad.

  In contrast, the battery pack according to the first embodiment has a structure in which a second holder 24 having an insulating function is further provided in addition to the first holder 23 for fixing the circuit board 21. Further, by bringing the surface of the second holder 24 into contact with the end surface of the battery element 4, the backup force by the battery cell can be evenly transmitted to the first holder 23 via the second holder 24. The circuit board 21 can be fixed more firmly.

  That is, by fixing the second holder 24 to the end face of the battery cell, the fixing force of the circuit board 21 can be improved as compared with the conventional structure shown in FIG. The second holder 24 also has a function of fixing a member such as a safety protection element 27 that is sandwiched between the first holder 23 and the second holder 24.

  The battery pack according to the first embodiment of the present invention also has the following excellent effects. In this battery pack, positioning holes 32 a to 32 b of the first holder 23 and positioning holes 37 a to 37 b of the second holder 24 are inserted into shafts 31 a to 31 b provided on the top cover 2. The top cover 2, the first holder 23, and the second holder 24 are physically constrained on one axis. Thereby, the positional relationship among the top cover 2, the first holder 23, and the second holder 24 is not broken.

  In addition, since the process of incorporating the first holder 23 and the second holder 24 into the top cover 2 is a very simple operation of passing a hole through the shaft, the assembly process of the battery pack can be simplified and simplified. Speed can also be improved. Further, since the insulation failure due to the misalignment does not occur unlike the insulation using the insulating tape 306, it is possible to reduce the occurrence of defective products due to work variations. Furthermore, there is an effect of reducing the number of workers by omitting unstable work such as pasting of the insulating tape 306, which has been performed in the conventional structure.

<Bottom cover>
The bottom cover 3 is a resin molded cover provided on the end surface on the bottom side of the battery pack. The bottom cover 3 is fitted into an opening of an exterior material formed by wrapping the battery cell with the exterior material, and is adhered to the battery cell by heat fusion or the like.

  Next, a method for manufacturing a battery pack according to the first 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 storage portion 15 for storing the battery element 4 is formed on the soft laminate material 1a by deep drawing, for example. At this time, as shown in FIG. 3A, the storage portion 15 of the soft laminate 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 accommodating part 15 formed in the soft laminate material 1a.

  Next, as shown in FIG. 3A, the hard laminate 1b is laminated at a position slightly shifted to the right with respect to the soft laminate 1a. Thereby, in the state where the soft laminate material 1a and the hard laminate material 1b are laminated, as shown in FIG. 3A, a left region where only the soft laminate material 1a is located and a right region where only the hard laminate material 1b is located Arise.

  The reason for shifting the position in this way is as follows. As will be described later, after folding the ends of the soft laminate 1a and the hard laminate 1b outside the bottom surface of the storage portion 15, the polypropylene layer of the soft laminate 1a and the polypropylene layer of the hard laminate 1b have a certain width. This is so that it can be bonded.

  Next, in the state of arrangement as shown in FIG. 3A, the four sides around the opening of the storage portion 15 are thermally welded while reducing the pressure. 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 storage portion 15.

  Next, as shown in FIG. 3A, a heat welding sheet 15 a having a predetermined shape is provided outside the bottom surface of the storage unit 15. The heat welding sheet 15a is an auxiliary member for bonding the nylon layer or the PET layer of the soft laminate material 1a by heating. Preferably, the thickness is about 10 μm to 60 μm in view of the total thickness and has a melting point of about 100 ° C. 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. 9, both ends of the soft laminate material 1a and the hard laminate material 1b, that is, the short sides 13a, 14a, 13b, and 14b are directed toward the outside of the bottom surface of the storage 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 storage portion 15. Thereby, the soft laminate material 1a and the hard laminate material 1b are fixed in a closed state so as to enclose the storage portion 15 in which the battery element 4 is stored. That is, a top side opening and a bottom side opening are formed.

  As shown in FIG. 10, in the 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. Arise. Further, a seam L2 is formed in which the short sides 13a and 14a of the soft laminating material 1a are in contact with each other or their end faces are opposed to each other through a slight gap inside the hard laminating material 1b.

FIG. 10 is an example in which the short sides 13a and 14a of the soft laminate 1a are in contact with each other or their end faces are opposed to each other through a slight gap, but the short sides 13a and 14a of the soft laminate 1a are You may make it a mutual end surface oppose through the clearance gap of a certain amount of width.

  As shown in FIG. 10, the surface protective layer 18a of the soft laminate material 1a is located in contact with the upper side of the heat welding sheet 15a. Therefore, the surface protective layer 18a has a structure sandwiching the heat welding sheet 15a, and the surface protective layers 18a can be bonded to each other by applying heat from the outside. Further, since the adhesive layer 16a and the adhesive layer 16b of the soft laminate material 1a and the hard laminate material 1b are opposed to each other, the adhesive 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>
First, the fitting process of the top cover 2 will be briefly described with reference to FIG. As shown in FIG. 11, first, the lead cut process of step S11 is performed with respect to the battery cell produced at the said process. Then, the step of welding the safety protection element 27 to the lead in step S12 → the step of welding the positive electrode lead 5a in step S13 to the circuit board 21 → the step of welding the negative electrode lead 5b in step 14 to the circuit board 21 is performed.

  Further, the top cover 2 assembling step at step 15 → the first holder 23 assembling step at step S16 → the lead bending step at step S17 is performed. Further, the second holder 24 assembling step at step S18 → the impulse welder step at step S19 → the assembling step at step S20 for incorporating the top cover 2 into the open surface of the exterior material 1 is performed. The top cover 2 is fitted into the opening of the exterior material 1 through the series of steps described above.

  Hereinafter, the fitting process of the top cover 2 will be described in detail with reference to FIGS. As shown in FIG. 12, after the positive electrode lead 5a and the negative electrode lead 5b are cut into a predetermined shape, the safety protection element 27 is connected to the negative electrode lead 5b by, for example, resistance welding or ultrasonic welding. The positive electrode lead 5a and the tab 22a are connected by, for example, resistance welding or ultrasonic welding. Further, the negative electrode lead 5b and the tab 22b are connected by, for example, resistance welding or ultrasonic welding. At this time, it arrange | positions so that the main surface of the circuit board 21 may become in parallel with an open surface.

  Next, as shown in FIG. 13, the circuit board 21 is incorporated into the top cover 2 so as to cover the circuit board 21. The top cover 2 is, for example, a resin molded product manufactured by injection molding in a separate process. In the top cover 2, for example, a holding unit that holds the circuit board 21 horizontally is provided. Further, three openings 17 are provided on the top surface of the top cover 2 at positions corresponding to the contact portions of the circuit board 21. A contact portion is desired to the outside through the opening 17. The width of the top cover 2 is selected to be smaller than the inner dimension of the height of the opening on the top side of the exterior material 1.

  Next, as shown in FIG. 14, the first holder 23 is incorporated into the top cover 2. The first holder 23 is a resin molded product manufactured by, for example, injection molding in a separate process. At both ends of the first holder 23, two positioning holes 32a to 32b (not shown in this figure) are provided. Two shafts 31a to 31b (not shown in this figure) at both ends of the top cover 2 are inserted into the two holes 32a to 32b.

  Further, the hook 36 provided on the first holder 23 enters the locking hole 34 of the top cover 2, whereby the top cover 2 and the first holder 23 are engaged. After incorporating the first holder 23 into the top cover 2, the top cover 2 is rotated 90 ° in the clockwise direction as indicated by an arrow R by bending the electrode leads 5 a to 5 b with hands or jigs.

  Next, as shown in FIG. 15, the second holder 24 is incorporated into the top cover 2. The second holder 24 is a resin molded product manufactured by, for example, injection molding in a separate process. At both ends of the second holder 24, two positioning holes 37a to 37b are provided. Two shafts 31a to 31b at both ends of the top cover 2 are inserted into the two holes 37a to 37b. The plate-like protrusions 39a to 39b provided on the second holder 24 cover the exposed portions of the tabs 22a to 22b and the electrode leads 5a to 5b connected thereto, thereby insulating these portions.

  When the second holder 24 is incorporated into the top cover 2, the shafts 31 a to 31 b provided on the top cover 2 pass through the positioning holes 37 a to 37 b of the second holder 24, and Projects upward.

  Then, in the state where the first holder 23 and the second holder 24 are incorporated in the top cover 2, the tip ends of the shafts 31a to 31b are dissolved by an impulse welder. As a result, the tips of the shafts 31a to 31b have a substantially hemispherical shape, and the top cover 2, the first holder 23, and the second holder 24 are securely fastened.

  Next, as shown in FIG. 16, the top cover 2 is pushed toward the top side opening (in the direction of arrow S1). Thereby, the top cover 2 is fitted into the opening on the top side.

<Bottom cover fitting process>
Next, as shown in FIG. 16, the side wall of the bottom cover 3 is pushed toward the opening of 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 metal such as copper is pressed from the top and bottom near the top end of the exterior material 1 to thermally weld the peripheral surface of the top cover 2 and the adhesive layer 16b 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 so that the peripheral surface of the bottom cover 3 and the adhesive layer 16b on the inner surface of the hard laminate material 1b are thermally welded. Also good.

<Resin injection process>
Next, molten resin is filled between the battery element 4 and the bottom cover 3 through a through hole (not shown) provided in 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. For example, polyamide hot melt, polyolefin hot melt, nylon, PP resin, PC resin, ABS resin, etc. Can be used.

  Note that a molten resin may be filled between the top cover 2 and the battery element 4. In this case, one or more through holes may be provided in the top cover 2 and the molten resin may be injected from the through holes. Through the above steps, the battery pack according to the first embodiment of the present invention is manufactured.

2. Second embodiment (second example of battery pack)
A battery pack according to a second embodiment of the invention will be described. In the second embodiment, the top cover assembly described in the first embodiment is used for a battery cell having higher sealing performance. Hereinafter, the battery pack according to the second embodiment will be described with reference to the drawings. In addition, the same number is attached | subjected to the site | part which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  FIG. 17 shows the appearance of a battery pack according to the second embodiment of the present invention. In this battery pack, a power generation element, which will be described later, is accommodated in a hard laminate material 51, and a top cover 2 and a bottom cover 3 that are resin-molded covers are fitted to openings at both ends.

  FIG. 18 is an exploded view showing the configuration of the battery pack according to the second embodiment of the present invention. As shown in FIG. 18, the battery pack includes a power generation element 53 in which the battery element 4 is covered with a soft laminate material 52, a circuit board 21 connected to the electrode leads 5a to 5b led out from the power generation element 53, The top cover 2 and the bottom cover 3 are configured. The power generation element 53 is covered with a hard laminate material 51 to form a battery cell.

  Similar to the battery pack according to the first embodiment, a first holder 23 is fitted to the top cover 2, and a circuit board 21 is disposed between the first holder 23 and the top cover 2. . Further, a second holder 24 is incorporated so as to face the first holder 23, and a safety protection element 27 is disposed between the first holder 23 and the second holder 24. Similarly to the first embodiment, the bottom cover 3 is provided at the bottom end portion of the battery pack and is fitted into the opening of the hard laminate material 51.

<Top cover, first holder, second holder, circuit board, safety protection element, bottom cover>
Since the top cover 2, the first holder 23, the second holder 24, the circuit board 21, the safety protection element 27, and the bottom cover 3 are the same as those in the first embodiment, detailed description thereof is omitted.

<Battery cell>
The battery cell 54 includes a power generation element 53 in which the battery element 4 is covered with a soft laminate material 52, and a hard laminate material 51 that covers the power generation element 53.

<Power generation element>
Since the battery element 4 is the same as that of the first embodiment, detailed description thereof is omitted.

<Soft laminate material>
The soft laminate material 52 has a function of covering the battery element 4 to prevent moisture from entering the interior, and is provided with a storage portion for storing the battery element 4 by deep drawing or the like. As the soft laminate material 52, the same material as the soft laminate material 1a described in the first embodiment can be used.

<Hard laminating material 51>
The hard laminate material 51 further covers the power generating element 53 in which the battery element 4 is covered with the soft laminate material 52, maintains the shape after bending, and can withstand deformation from the outside. .

  FIG. 19 is a cross-sectional view showing the configuration of the hard laminate material 51. As shown in FIG. 19, the hard laminate 51 has a moisture-proof and insulating laminated structure in which a first adhesive layer 51a, a second adhesive layer 51b, a metal layer 51c, and a surface protective layer 51d are sequentially laminated. Have.

  The metal layer 51c is made of a hard metal material, and aluminum, stainless steel, copper, titanium, tin, tin, nickel-plated iron, or the like can be used as appropriate. Among these, aluminum (Al) and austenitic stainless steel are most preferable, and it is particularly preferable to use aluminum based on JIS standards such as 3003H18, 3004H18, 1N30H18, or stainless steel based on JIS standards such as SUS304.

  For the surface protective layer 51d, the same material as the surface protective layer 18a described in the first embodiment can be used. The second adhesive layer 51b can be made of the same material as the adhesive layer 16b of the first embodiment.

  The first adhesive layer 51 a is for bonding the power generating element 53 and the hard laminate 51 covered with the soft laminate 52 without separately providing an adhesive member. As the first adhesive layer 51a, a resin material that is excellent in adhesiveness with Ny, PET, PEN and the like used as the surface protective layer of the soft laminate 52 and whose melting temperature does not affect the battery element 4 Is used. The first adhesive layer 51a can be made of a resin material having a lower melting point than the material used for the second adhesive layer 51b.

  As the first adhesive layer 51a, specifically, ethylene vinyl alcohol resin (EVA), acid-modified polypropylene, ethylene vinyl acetate copolymer, ethylene acrylic acid copolymer, ethyl acrylate copolymer, methyl acrylate copolymer, methacrylic acid copolymer, Methyl methacrylate copolymer, polyacrylonitrile, polyamide resin, polyester resin, and ionomer can be used, and a plurality of types can be selected and used. The first adhesive layer 51a is a method in which these materials are bonded together as a film, a method in which a resin material (hot melt resin) melted by heat is applied and cooled, a hot melt resin is diluted with a solvent, and after application, The method of drying can be used.

  In such a hard laminate material 51, the first adhesive layer 51a is provided with a thickness of about 1 μm to 5 μm. Moreover, since the metal layer 51c has a function of using the outermost package of the battery pack to maintain the strength of the battery pack, the metal layer 51c is used in a thickness of about 50 μm to 100 μm. The surface protective layer 51d is used in a thickness of about 9 to 15 μm, and the second adhesive layer 51b is used in a thickness of about 25 to 35 μm.

  The second adhesive layer 51b is used as a welding layer when the top cover 2 and the bomb cover 3 are thermally welded later. For this reason, a resin material having good adhesion to the top cover 2 and the bottom cover 3 is selected. The second adhesive layer 51 b also has a cushion function when the hard laminate material 51 is bonded to the power generation element 53. That is, when the soft laminate material 52, which is an exterior material of the power generation element 53, and the hard laminate material 51 are thermally welded via the first adhesive layer 51a, each laminate film has fine irregularities on the surface. Therefore, there are cases where the adhesiveness is not excellent. Since the second adhesive layer 51b having a thickness of about 25 μm to 35 μm is provided, the second adhesive layer 51b serves as a cushion, and satisfactorily adheres laminated films having fine irregularities on the surface. Can be made.

<Method for manufacturing battery pack>
A method for manufacturing a battery pack according to a second embodiment of the present invention will be described.

<Battery element manufacturing process>
Since the battery element 4 can be manufactured by the same process as in the first embodiment, detailed description thereof is omitted.

<Power generation element production process>
The battery element 4 produced in the same manner as in the first embodiment is packaged with a soft laminate material 52 and molded to produce a power generation element 53 as shown in FIG.

  As shown in FIG. 21, the soft laminate 52 has a recess 52a formed by deep drawing, and after the battery element 4 is accommodated in the recess 52a, the soft laminate 52 is folded and the soft laminate 52 is opened to the recess 52a. Cover the part. Next, sealing is performed by thermally welding three sides of the periphery of the battery element 4 excluding the folded side under reduced pressure. Next, the power generation element 53 is formed by folding back two sides excluding the folded side and the side where the electrode lead 5 is extended.

<Battery cell production process>
The power generation element 53 thus produced is covered with a hard laminate material 51 to produce a battery cell 54. First, as shown in FIG. 22A, after placing the hard laminate 51 on the bottom surface of the power generation element 53, the hard laminate material 51 is bent so as to wrap the power generation element 53, and the hard laminate material 51 is Exterior so that the ends meet. Next, a heater block is applied from the upper surface and the bottom surface of the power generation element 53, and heating is performed while applying pressure at a temperature at which the resin material of the first adhesive layer 51a is melted. The resin material of the first adhesive layer 51 a is melted to become an adhesive, and bonds the hard laminate material 51 and the power generation element 53. Thereby, the battery cell 54 whose cross section is shown in FIG. 22B is manufactured.

  Although the temperature of the heater block varies depending on the resin material of the first adhesive layer 51a, it is equal to or higher than the melting temperature of the resin material of the first adhesive layer 51a and is higher than the melting temperature of the resin material used for the second adhesive layer 51b. Also make the temperature low. Accordingly, only the resin material of the first adhesive layer 51a can be melted and bonded without melting the resin material of the second adhesive layer 51b.

  Further, when the heating temperature exceeds 120 ° C., it is considered that the battery element 4 is affected. For example, the separators 53a and 53b used in the battery element 4 are often made of polyethylene (PE). However, since the melting point of PE is about 120 ° C., it is considered that safety and battery function are lowered. From this, the temperature of the heater block is heated up to about 110 ° C.

<Top cover mating process>
The top cover 2 accommodates the circuit board 21 and is fitted to the opening surface on the top side of the battery cell 54 in a state in which the first holder 23, the second holder 24, and the safety protection element 27 are incorporated. Since the top cover fitting step is the same as in the first embodiment, detailed description thereof is omitted.

  The first adhesive layer 51a heated and melted when the hard laminate film 51 and the power generation element 53 are bonded is pressed by the side wall of the top cover 2 when the top cover 2 is fitted, and the battery cell 54 Move to the back. As described above, since the resin material having a lower melting temperature than the second adhesive layer 51b is used for the first adhesive layer 51a, when the hard laminate film 51 and the power generation element 53 are bonded, Only the first adhesive layer 51a is melted. For this reason, the first adhesive layer 51a can be moved without moving the second adhesive layer 51b used for bonding to the top cover 2, and the second adhesive layer 51b and the top cover 2 can be moved. It can be fitted in an opposed state.

<Bottom cover fitting process>
The bottom cover 3 can be fitted in the same process as in the first embodiment. At this time, as in the case of the top cover 2 described above, the melted first adhesive layer 51a is pushed by the bottom cover 3 and moves to the back of the battery cell 54, and therefore the second adhesive layer 51b and the bottom The cover 3 can be fitted with the cover 3 facing each other.

<Heat welding process>
Thermal welding can be performed in the same process as in the first embodiment. At this time, the temperature of the heater head is set so as to be higher than that in the battery cell manufacturing process and equal to or higher than the melting temperature of the resin material of the second adhesive layer 51b. As a result, the second adhesive layer 51b that was not melted when the hard laminate material 51 is bonded to the power generation element is melted, and the top cover 2 and the bottom cover 3 and the second adhesive layer 51b are welded. Through the above steps, the battery pack according to the second embodiment of the present invention is manufactured.

  The present invention will be described below with reference to examples. The inventor of the present application conducted a test to confirm the effect of improving the effect of backing up the circuit board 21 by providing the second holder 24 described in the first embodiment and the second embodiment.

  A battery pack having the structure shown in FIG. 1 (battery pack according to the first embodiment) was manufactured using the top cover assembly having the structure shown in FIG. 5 and the conventional top cover assembly having the structure shown in FIG. The test described below was conducted with the top cover assembly having the structure shown in FIG. 5 as the battery pack of Example 1 and the top cover assembly having the structure shown in FIG. 8 as the battery pack of Comparative Example 1.

(Substrate backup effect confirmation test)
The backup effect was confirmed by looking at the amount of strain on the board when the terminal surface was loaded. The confirmation test will be described with reference to FIG. 23 and FIG.

  As shown in FIG. 23, while confirming the load value of the push gauge 94, a load was continuously applied from 1 to 5 (N) to the terminals 96 to 98 exposed from the opening of the top cover 92. In FIG. 24, three points are measured per terminal, as indicated by points a to c on the (−) terminal 96, points df on the (TH) terminal 97, and points j to h on the (+) terminal 98, The amount of mutation at each point of each terminal was read from the dial gauge 95.

  FIG. 25 and FIG. 26 show graphs summarizing the test results. The graph shown in FIG. 25 is a graph summarizing the test results of the battery pack of Comparative Example 1. In FIG. 25, a line 103 is a plot of the average value of the amount of variation at each of the points a to c of the (−) terminal 96 against the load value. A line 102 is a plot of the average value of the amount of variation at each of the points d to f of the (Th) terminal 97 against the load value. A line 101 is obtained by plotting the average value of the amount of variation at each of the points j to h of the (+) terminal 98 against the load value.

  FIG. 26 is a graph summarizing the test results of the battery pack of Example 1. In FIG. 26, a line 104 is a plot of the average value of the amount of variation at each of the points a to c of the (−) terminal 96 against the load value. A line 106 is obtained by plotting the average value of the amount of variation at each of the points d to f of the (Th) terminal 97 against the load value. A line 105 is obtained by plotting the average value of the amount of variation at each of the points j to h of the (+) terminal 98 against the load value.

  When the graph shown in FIG. 25 and the graph shown in FIG. 26 are compared, in Example 1, the first holder 23 is backed up by the entire surface by the second holder 24. It was confirmed that the amount of displacement was stable for all three terminals.

  Further, a battery pack having the configuration shown in FIG. 17 (battery pack according to the second embodiment) was manufactured using the top cover assembly having the configuration shown in FIG. 5 and the conventional top cover assembly having the configuration shown in FIG. A battery pack according to Example 2 having a top cover assembly having the structure shown in FIG. 5 and a battery pack having a structure having a top cover assembly having a structure shown in FIG. The same test as the battery pack was performed. As a result, the same results as the tests performed on the battery packs of Example 1 and Comparative Example 1 were confirmed. That is, in Example 2, since the first holder 23 is backed up by the entire surface by the second holder 24, the circuit board can be held on average, and a stable displacement amount for all three terminals. It was confirmed that

3. Other embodiment (modification)
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, the present invention is not limited to the battery pack according to the first embodiment and the battery pack according to the second embodiment. For example, the present invention can be applied if the exterior material is a battery pack having a configuration in which battery elements are housed in an exterior material having an opening, for example.

  The structure of the battery element is not limited to the battery elements described in the battery pack according to the first embodiment and the battery pack according to the second embodiment. For example, a laminate in which a positive electrode, a polymer electrolyte and / or a separator, and a negative electrode are stacked may be used as a battery element.

  Of course, a battery element having a configuration not using the polymer electrolyte, for example, a battery element having a structure in which a positive electrode and a negative electrode and a separator disposed between the positive electrode and the negative electrode are wound may be used. The present invention can also be applied to a battery pack configured such that the battery element is housed in an exterior material such as a laminate film, a liquid electrolyte is injected, and the battery element is immersed in the liquid electrolyte.

DESCRIPTION OF SYMBOLS 1 ... Exterior material 2 ... Top cover 4 ... Battery element 5a-b ... Electrode lead 21 ... Circuit board 22a-b ... Tab 23 ... 1st holder 24 ... -2nd holder 27 ... Safety protection element 31a-31b ... Shaft 39a-39b ... Plate-shaped protrusion part

Claims (10)

A battery element;
An exterior material for storing the battery element;
A cover for closing the opening of the exterior material;
A circuit board housed in the cover and connected to the battery element by a conductive member;
A first holder accommodated in the cover facing the circuit board;
A battery pack comprising: a second holder that is accommodated in the cover so as to face the first holder and covers the conductive member. The cover has a shaft extending from the surface facing the first holder to the first holder side,
2. The battery pack according to claim 1, wherein the shaft is inserted into a positioning hole provided in the first holder and a positioning hole provided in the second holder. The second holder is pressed toward the first holder by the end face of the battery element,
The battery pack according to claim 1, wherein the first holder is pressed toward the circuit board by the second holder.   2. The battery pack according to claim 1, wherein the conductive member is covered with a surface of the second holder that protrudes to the side facing the first holder.   The battery pack according to claim 2, wherein the cover has a plurality of the shafts.   The battery pack according to claim 2, wherein the cover has the shaft at both ends of a surface facing the first holder. The first holder has a notch through which the lead and the conductive member between the lead and the circuit board pass,
The battery pack according to claim 4, wherein the surface of the second holder is a plate surface of a plate-like protruding portion that enters the notch portion. The battery pack according to claim 1, wherein a safety protection element is sandwiched between the first holder and the second holder as the conducting member. The battery pack according to claim 1, wherein the cover is a top cover provided at an end portion on a top side of the battery pack. The battery pack according to claim 1, wherein the exterior material is composed of a soft laminate material and a hard laminate material.

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