JP4797385B2 - Battery pack - Google Patents

Description

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

  In recent years, many portable electronic devices such as a camera-integrated VTR (Videotape recorder), a mobile phone, or a laptop computer have appeared, and their size and weight have been reduced. Along with this, the demand for batteries used as power sources for portable electronic devices is growing rapidly, and the battery packs connected to the devices are lighter and thinner in order to reduce the size and weight of the devices. There is a need to use the storage space efficiently. As a battery satisfying such requirements, a lithium ion battery having a large energy density and output density is most suitable.

Among these, lithium ion polymer secondary batteries using a gel polymer electrolyte are widely used in order to prevent liquid leakage that becomes a problem when a conventional liquid electrolyte is used. Lithium-ion polymer secondary batteries have electrode elements connected to each other, laminated a strip-like positive electrode and negative electrode coated with polymer electrolyte on both sides via a separator, and then wound in the longitudinal direction. Battery cells. An electrode terminal connected to the positive electrode and the negative electrode is led out from the battery cell. After connecting the circuit board, the battery terminal is housed in a plastic mold case to form a battery pack. Patent Document 1 below describes an example of a lithium ion polymer secondary battery having such a configuration.
JP 2002-260608 A

  However, in the conventional configuration in which the battery cell is housed 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 increased by about 0.8 to 1.0 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 conventional battery pack has been forced to increase in volume by 1.3 to 1.4 times the cell volume.

  Further, storing the battery cell in the mold case deteriorates the heat dissipation, and there is a possibility that the battery performance may be deteriorated or the battery may generate heat.

  Therefore, we house the battery element in a hard exterior material having first and second openings at both ends, and first and second covers manufactured by resin molding with respect to the first and second openings. A battery pack is proposed in which a circuit board to be joined to an electrode terminal of the battery element is housed in a first cover fitted to the first opening.

  In the battery pack having this configuration, since it is not necessary to store the battery element in the mold case, it is excellent in volumetric efficiency (electric capacity per volume / 1 battery pack), has good heat dissipation, and contributes to improvement in battery performance. In addition, the battery pack can be easily assembled and has a high productivity.

  In the battery pack as described above, when the circuit board 9 is housed in the top cover 4 composed of the upper holder 4a and the lower holder 4b and is fitted into one opening of the exterior member 5, as shown in FIG. The electrode terminal 2 joined to the circuit board 9 is accommodated in the battery pack so as to be folded. In this case, if there is sufficient space between the battery element 6 and the top cover 4, the bent electrode terminal 2 can be configured without interfering with the portion 7 facing the electrode terminal lead-out portion of the upper holder 4a. However, this is contrary to the original purpose of the battery pack with improved space efficiency.

  Further, when this space is narrowed, due to the influence of the structure of the electrode terminal lead-out portion, the fused portion between the upper holder 4a provided on the electrode terminal lead-out portion side and the exterior material 5 becomes extremely small. The heat-sealing strength with the exterior material 5 will be insufficient. When the battery thickness is relatively small, as shown in FIG. 1B, the portion 8 facing the electrode terminal lead-out portion on the bottom surface of the lower holder 4b presses the electrode terminal 2, and the electrode terminal protrudes and curves in the battery thickness direction. In the electrode terminal portion, the battery thickness may become larger than other portions. In this case, there is a possibility that the size of the battery pack insertion part on the electronic device side may not be matched.

  Therefore, in this invention, the electrode terminal interferes with the top cover inside the battery pack, the electrode terminal protrudes and curves in the battery thickness direction, and the battery thickness outer dimension at the electrode terminal portion becomes larger than other parts. The goal is to prevent and get a more productive battery pack.

In order to solve the above-described problems, a battery pack according to the present invention includes a rectangular or flat battery element housed in a hard exterior material having first and second openings at both ends, and the first and second openings. Is covered with a first cover and a second cover, and a circuit board to be joined to the electrode terminal lead of the battery element is housed in the first cover fitted into the first opening. The cover includes an upper holder manufactured by resin molding that holds the circuit board from the side opposite to the battery element side of the circuit board, and a lower holder manufactured by resin molding that is disposed on the battery element side of the circuit board. In a rectangular or flat battery pack having at least an upper holder and a lower holder that are bonded or bonded by mechanical engagement means, the upper holder has an electrode terminal lead from which the electrode terminal is derived from the battery element. It characterized by having a first notch in a portion facing section.

In addition, the lower holder includes a bottom surface portion facing the battery element with one main surface facing, and has a second notch in a portion facing the electrode terminal lead-out portion of one end surface of the bottom surface portion. Of the other end surface facing the one end surface of the bottom surface, it is preferable to have a third notch in a portion facing the second notch. Thereby , the said malfunction can be eliminated more effectively.

  According to this invention, by providing a notch in the cover that stores the circuit board, it is possible to sufficiently store the curved shape of the electrode terminal that is bent and stored even when the cover is fitted to the exterior material. The battery pack thickness is not affected even after heat-sealing the cover and the exterior material. Moreover, it becomes difficult to peel off the heat-sealed portion, and the quality can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 shows an example of the configuration of a battery pack of a lithium ion polymer secondary battery to which the present invention is applied. In this battery pack, a battery element is housed in a hard laminate material as an exterior material, and resin-molded covers are fitted to openings at both ends.

  FIG. 3 shows the configuration of the battery element 20 used in this battery pack. FIG. 3A is a perspective view of the battery element 20, and FIG. 3B is a cross-sectional view showing the configuration of the winding end portions of the positive electrode 21 and the negative electrode 22. The battery element 20 includes a belt-like positive electrode 21, a separator 23a, a belt-like negative electrode 22 disposed to face the positive electrode 21, and a separator 23b, which are sequentially stacked and wound in the longitudinal direction. A polymer electrolyte 24 is applied to both surfaces of the negative electrode 22. As shown in FIG. 3B, the polymer electrolyte is applied so as to completely cover the terminal portions of the positive electrode 21 and the negative electrode 22. In addition, a positive electrode terminal 12a connected to the positive electrode 21 and a negative electrode terminal 12b connected to the negative electrode 22 are led out from the battery element 20 (hereinafter referred to as the electrode terminal 12 when not referring to a specific terminal), Sealants 13a and 13b, which are resin pieces, are provided on both surfaces of the positive electrode terminal 12a and the negative electrode terminal 12b to improve the adhesion to a laminate film to be packaged later. Is coated).

  Hereinafter, the material of the battery element will be described in detail.

[Positive electrode]
The positive electrode 21 is formed by forming a positive electrode active material layer containing a positive electrode active material on both surfaces of a positive electrode current collector. The positive electrode current collector is made of a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, or a stainless steel (SUS) foil.

  The positive electrode active material layer includes, for example, a positive electrode active material, a conductive agent, and a binder. These are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. Next, the slurry is uniformly applied on the positive electrode current collector by a doctor blade method or the like, dried at a high temperature, and the solvent is removed. Here, the positive electrode active material, the conductive agent, the binder, and the solvent only have to be uniformly dispersed, and the mixing ratio is not limited.

As the positive electrode active material, mainly 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 and 1.10 or less). A composite oxide of lithium and a transition metal is used. As the transition metal constituting the lithium composite oxide, cobalt (Co), Ni, manganese (Mn) or the like is used.

Specific examples of such a lithium composite oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _y Co _1-y O ₂ (0 <y <1). A solid solution in which a part of the transition metal element is substituted with another element can also be used. Examples thereof include LiNi _0.5 Co _0.5 O ₂ and LiNi _0.8 Co _0.2 O ₂ . These lithium composite oxides can generate a high voltage and have an excellent energy density. _{Furthermore, 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.

  As the conductive agent, for example, a carbon material such as carbon black or graphite is used. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride, or the like is used. Moreover, as a solvent, N-methylpyrrolidone etc. are used, for example.

  The positive electrode 21 has a positive electrode terminal 12a connected to one end of the current collector by spot welding or ultrasonic welding. The positive electrode terminal is preferably a metal foil or a mesh-like one, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the positive electrode terminal include Al.

[Negative electrode]
The negative electrode 22 is formed by forming a negative electrode active material layer containing a negative electrode active material on both surfaces of a negative electrode current collector. The negative electrode current collector is made of a metal foil such as a copper (Cu) foil, a Ni foil, or a stainless steel foil.

  The negative electrode active material layer includes, for example, a negative electrode active material, a conductive agent if necessary, and a binder. These are uniformly mixed to form a negative electrode mixture, and this negative electrode mixture is dispersed in a solvent to form a slurry. Next, this slurry is uniformly applied on the negative electrode current collector by a doctor blade method or the like, dried at a high temperature, and the solvent is blown off. Here, the negative electrode active material, the conductive agent, the binder, and the solvent only have to be uniformly dispersed, and the mixing ratio is not limited.

As the negative electrode active material, lithium metal, a lithium alloy, a carbon material that can be doped / undoped with lithium, or a composite material of a metal material and a carbon material is used. Specific examples of carbon materials that can be doped / undoped with lithium include graphite, non-graphitizable carbon, graphitizable carbon, and the like. More specifically, pyrolytic carbons and cokes (pitch coke, needle coke). , Petroleum coke), graphites, glassy carbons, organic polymer compound fired bodies (phenol resins, furan resins, etc., calcined at an appropriate temperature), carbon fibers, activated carbon and other carbon materials are used. be able to. 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.

  In addition, various types of metals can be used as materials capable of alloying lithium, but tin (Sn), cobalt (Co), indium (In), Al, silicon (Si), and alloys thereof can be used. Often used. When metal lithium is used, it is not always necessary to use powder as a coating film with a binder, and a rolled Li metal plate may be used.

  As the binder, for example, polyvinylidene fluoride, styrene butadiene rubber or the like is used. Moreover, as a solvent, N-methylpyrrolidone, methyl ethyl ketone, etc. are used, for example.

  Similarly to the positive electrode 21, the negative electrode 22 has a negative electrode terminal 12 b connected to one end of the current collector by spot welding or ultrasonic welding. The negative electrode terminal is preferably a metal foil or a mesh-like one, but there is no problem even if it is not a metal as long as it is electrochemically and chemically stable and can conduct electricity. Examples of the material for the negative electrode terminal include copper and Ni.

  In addition, although it is preferable that the positive electrode terminal 12a and the negative electrode terminal 12b are derived | led-out from the same direction, there is no problem even if it derive | leads out from which direction as long as a short circuit etc. do not occur and there is no problem in battery performance. Moreover, the connection location of the positive electrode terminal 12a and the negative electrode terminal 12b will not be restricted to said example, if the electrical contact is taken and the attachment location and the attachment method.

[Polymer electrolyte]
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, for example, polymer materials such as poly (vinylidene fluoride), poly (vinylidene fluoride-co-hexafluoropropylene), poly (vinylidene fluoride-co-trifluoroethylene), and mixtures thereof may be used as the fluorine-based polymer. used.

  As the electrolyte material, an electrolyte salt and a non-aqueous solvent that are generally used in lithium ion batteries can be used. Specific examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, ethyl propyl carbonate, and carbonates thereof. And other solvents in which hydrogen is substituted with halogen. One of these solvents may be used alone, or a plurality of these solvents may be mixed with a predetermined composition.

As the electrolyte salt, one that dissolves in the non-aqueous 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, LiPF 6, LiBF 4, LiN} (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LiClO 4 and the like. The electrolyte salt concentration is not a problem as long as it can be dissolved in the above solvent, but the lithium ion concentration is in the range of 0.4 mol / kg or more and 2.0 mol / kg or less with respect to the non-aqueous solvent. Is preferred.

[Separator]
The separator is made of, for example, a porous film made of a polyolefin-based material such as polypropylene (PP) or polyethylene (PE), or a porous film made of an inorganic material such as a ceramic nonwoven fabric. A structure in which a porous film is laminated may be used. Among these, polyethylene and polypropylene porous films are the most effective.

  In general, the thickness of the separator is preferably 5 to 50 μm, more preferably 7 to 30 μm. If the separator is too thick, the amount of the active material filled decreases, the battery capacity decreases, and the ionic conductivity decreases and the current characteristics deteriorate. On the other hand, if the film is too thin, the mechanical strength of the film decreases.

  The battery element 20 produced as described above is packaged with a hard laminate material 11a and a soft laminate material 11b and molded to produce battery cells 16.

  FIG. 4 shows the configuration of the battery cell 16. The battery cell 16 is produced by arranging a hard laminate material 11a and a soft laminate material 11b on the upper and lower sides of the battery element indicated by reference numeral 20, heat-sealing, and then forming the hard laminate material 11a as an exterior. To do. The soft laminate material 11b is provided with a recess for arranging the battery element 20, and the recess is formed by drawing from the non-axially stretched polypropylene (CPP) layer side which is the inner resin layer.

  FIG. 5 shows main structures of the hard laminate material 11a and the soft laminate material 11b. The hard laminate material 11a and the soft laminate material 11b have a three-layer structure in which a metal layer indicated by reference numeral 30 is sandwiched between an outer resin layer 31 and an inner resin layer 32, and is a multilayer having moisture resistance and insulation properties. It is a film. The metal layer 30 plays the most important role in protecting the battery element by preventing the ingress of moisture, oxygen and light, and aluminum (Al) is most often used because of its lightness, extensibility, price, and ease of processing. . Nylon (Ny), polyethylene terephthalate (PET), or polyethylene naphthalate (PEN) is used for the outer resin layer 31 because of its beautiful appearance, toughness, and flexibility. The inner resin layer 32 is a portion that is melted by heat or ultrasonic waves and fused to each other, and unstretched polypropylene (CPP) or polyethylene (PE) is frequently used.

  The metal layer 30 and the outer resin layer 31 are bonded together by providing an adhesive layer 33. On the other hand, the metal layer 30 and the inner resin layer 32 are not only the method of providing the adhesive layer 34, but also the method of heating and melting CPP or PE and bonding it to the metal layer 30, or the method of bonding the CPP film or PE film with a heat roller or the like. Various methods can be used.

  When Al is used as the metal layer of the hard laminate 11a, Al (JIS A3003P-H18) or (JIS A3004P-H18) that is not annealed is used. In addition to the above-mentioned Al, copper (Cu), iron, nickel (Ni), stainless steel (SUS), titanium (Ti), or the like can be used for the metal layer. When Al is used as the metal layer of the soft laminate 11b, annealed Al (JIS A8021P-O) or (JIS A8079P-O) is used.

  The battery element 20 is accommodated in the recess provided in the soft laminate 11b, and the hard laminate 11a is stacked so as to cover the opening of the recess. Each of the hard laminate material 11a and the soft laminate material 11b is disposed so that the CPP layers (or PE layers), which are the inner resin layers, face each other.

  Next, the four sides around the battery element 20 are heat-sealed under reduced pressure and sealed. Generally, when the electrode terminal is taken out from the interface of the sealing portion and the laminate sheathing material is sealed, an elastic body such as rubber is lined on the surface to absorb the thickness of the electrode terminal, or the upper and lower heater heads A notch is provided on the surface (the surface in contact with the laminate film). When a flat metal head is used, a large pressure is applied to the electrode terminal part during heat sealing, preventing the electrode terminal from being cut, or preventing the metal head from hitting the part that does not sandwich the electrode terminal, resulting in poor sealing performance. Because.

  Further, the hard laminate material 11a and the soft laminate material 11b are curved along the shape of the battery element and molded so as to have an elliptical cross section like the battery cell 16 of FIG. The battery pack 10 is produced so as to protect the battery element 20 as an exterior.

  At this time, it is preferable to arrange an adhesive sheet outside the bottom surface of the recess provided in the soft laminate 11b. The pressure-sensitive adhesive sheet is an auxiliary member used for bonding the Ny layers of the soft laminate 11b, the PET layers, or the PEN layers at a high temperature.

  Next, the positive terminal 12a and the negative terminal 12b led out from the top part of the battery cell 16 molded into a predetermined shape and the protection circuit mounted in advance on the circuit board are fixed by resistance welding, ultrasonic welding, or the like. . The circuit board connected to the battery element 20 is inserted into a top cover 14 formed by fitting a preformed upper holder 14a and lower holder 14b as shown in FIG. 6, for example.

  In addition to a protection circuit including temperature protection elements such as a fuse, PTC, and thermistor, an ID for identifying the battery pack, a resistor, and the like are mounted on the circuit board, and a plurality of contact portions are formed. The protection circuit is also applied to a protection circuit including an IC for monitoring a secondary battery and controlling a field effect transistor (FET) and a charge / discharge control FET.

  The thermal resistance element (Positive Temperature Coefficient: PTC element) is connected in series with the battery element, and when the temperature of the battery becomes higher than the set temperature, the electrical resistance increases rapidly and the current flowing through the battery is substantially reduced. Shut off. 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. In addition, ICs that monitor secondary batteries and control FETs, and protection circuits that include charge / discharge control FETs, can generate heat and fire when the secondary battery terminal voltage exceeds 4.3V to 4.4V. Therefore, if the voltage of the secondary battery exceeds 4.3V to 4.4V, the charge control FET is turned off and charging is prohibited. Furthermore, if the secondary battery terminal voltage is overdischarged to below the discharge prohibition voltage and the secondary battery voltage becomes 0V, the secondary battery may be shorted internally and cannot be recharged. When the voltage falls below the discharge inhibition voltage, the discharge control FET is turned off and discharge is prohibited.

  In the battery pack as described above, when the circuit board 9 is housed in the top cover 4 composed of the upper holder 4a and the lower holder 4b and is fitted into one opening of the exterior member 5, as shown in FIG. The electrode terminal 2 joined to the circuit board 9 is accommodated in the battery pack so as to be folded.

  In order to facilitate understanding of the present invention, FIG. 6 shows the positional relationship between the electrode terminal lead-out portion and the upper holder 4a in a conventional battery pack. In the electrode terminal lead-out portion indicated by the dotted line in FIG. 6, since the electrode terminal is led out from the substantially end portion of the hard laminate material that is the exterior material, when the top cover is fitted, the upper holder indicated by the thick line in FIG. The part facing the electrode terminal lead-out part 4 a presses the electrode terminal 2.

  In this case, in order to prevent the bent electrode terminal 2 from interfering with a portion facing the electrode terminal lead-out portion of the upper holder 4a, a space is provided between the top cover 4 and the battery element, or an exterior material. It is necessary to design the fitting portion to be heat-sealed short. However, the former has poor space efficiency, and the latter cannot sufficiently obtain the heat-sealing strength of the top cover and the hard laminate material.

  Therefore, as shown in FIG. 7, in the present invention, the notch 19a is provided only in a part where the electrode terminal 12 of the upper holder 14a interferes. The state of the electrode terminal lead-out portion when such an upper holder 14a is fitted is shown in FIG. As shown in FIG. 8, the fitting portion of the upper holder 14a is inserted to the end of the soft laminate material 14b. However, the notch 19a is provided in the upper holder 14a, so that the electrode terminal 12 and the upper holder 14a are provided. It can be seen that no interference occurs. Thus, by providing a notch only in the portion of the upper holder 14a facing the electrode terminal 12, the space between the top cover 14 and the battery element 20 is reduced, and a sufficient heat-sealing strength is maintained. A battery pack without interference between the electrode terminal 12 and the top cover 12 can be manufactured.

  Furthermore, in order to prevent the electrode terminal 12 from interfering with the lower holder and being pushed and swelled in the battery thickness direction when the battery pack thickness is small, as shown in FIG. 9, the electrode terminal routing route on the bottom surface of the lower holder 14b Cutouts 19b and 19c are provided at portions corresponding to the above, and the electrode terminal 12 is bent so as to be housed in the cutouts 19b and 19c.

  In this case, by providing the notches 19b and 19c on the side surface of the bottom surface of the lower holder 14b, the area of the bottom surface portion having the notches is reduced, and at the same time the strength of the lower holder 14b itself is reduced. Parts warp easily during resin molding. Therefore, as shown in FIG. 9, in order to maintain the strength of the component and the moldability of the component, it is desirable to provide a protruding wall 17 having a height equal to or higher than the thickness of the bottom surface portion in the longitudinal direction of the bottom surface portion.

  Here, FIG. 10 shows the positional relationship between the lower holder 14b and the electrode terminal 12 when the top cover is fitted. 10A is a schematic view when the lower holder 14b and the battery element 20 are arranged so that the electrode terminal lead-out portion of the battery cell is on the bottom, and FIG. 10B is such that the electrode terminal lead-out portion of the battery cell is on the top. It is a schematic diagram at the time of arrange | positioning the lower holder 14b and the battery element 20 in FIG. In addition, the position of the lower holder 14b when the top cover is fitted is close to the battery element 20, but in FIG. 10, the lower holder 14b and the battery element 20 are separated from each other for the sake of explanation.

  From FIG. 10, by providing the notches 19b and 19c at predetermined positions of the lower holder 14b, it is possible to secure a space for storing the electrode terminals 12 and prevent pressure on the electrode terminals 12 and an increase in battery thickness. I understand that I can do it.

  As described above, when the battery pack thickness is small, the upper holder 14a provided with the notches 19a and the lower holder 14b provided with the notches 19b and 19c are used in combination as shown in FIG. It is possible to effectively prevent pressure on the electrode terminal.

  In addition, when the battery pack thickness is relatively large, by making the dimension in the battery thickness direction of the bottom portion of the lower holder 14b smaller than the upper holder, it is possible to obtain the same effect as when notches are provided, The lower holder 14b is not necessarily required to have a notch. Further, when the battery pack thickness is large, the size of the upper holder 14a in the battery thickness direction is also large. Therefore, there is no problem in strength even if the size of the lower holder in the battery thickness direction is smaller than that of the upper holder 14a. . On the other hand, as long as the configuration of the battery cell used in the present invention is used, the position of the electrode terminal lead-out portion does not change even when the battery becomes thick, and thus the upper holder 14a needs to be cut out.

  Below, with reference to FIGS. 12-15, the flow until a circuit board is accommodated in a top cover and it joins with the hard laminate material 11a which is an exterior material is demonstrated. 12 to 14 are perspective views showing how the top cover 14 is fitted, and FIG. 15 is a cross-sectional view showing how the top cover 14 and the electrode terminals 12 are bent.

  First, as shown in FIG. 12, the circuit board 18 bonded to the battery cell 16 is arranged so as to cover the upper holder 14a, and then, as shown in FIGS. 13 and 15A, the lower holder 14b is attached to the upper holder 14a. The circuit board 18 is accommodated in accordance with the position. Further, as shown in FIGS. 14 and 15B, the direction of the top cover 14 is changed so that the lower holder 14b is located at a position close to the battery cell 16, and after fitting into one opening of the battery cell 16 (FIG. 15C and FIG. 15). 15D), the outer cover material of the top cover 14 and the battery cell 16 is joined by thermal fusion. When the top cover 14 is fitted, the electrode terminal 12 is bent so as to be accommodated in the notches 19b and 19c of the lower holder.

  From FIG. 15D, by providing the notches 19a, 19b and 19c in the upper holder 14a and the lower holder 14b, respectively, the pressure to the electrode terminal lead-out portion of the battery cell 16 is eliminated, and the battery thickness can be increased more effectively. It can be seen that it can be prevented. Moreover, since the electrode terminal 12 is bent and accommodated in the notch 19b of the lower holder 14b, it is necessary to have a notch that accommodates at least two electrode terminals 12 each coated with the sealant 13 on both sides. The other notch 19c is a route for routing the electrode terminal 12, and may be deep enough to accommodate one electrode terminal 12 covered with the sealant 13.

  As shown in FIG. 1, a resin-molded rear cover 15 produced by injection molding is fitted in the opening opposite to the opening into which the top cover 14 is fitted, and the rear cover 14 and the battery cell are bonded by thermal fusion. The hard laminate material 11a which is 16 exterior materials is joined. The joining of the rear cover 15 and the exterior material is not limited to thermal fusion, and a method of pouring and joining a warmed resin material (hot melt agent) can be used in combination. In addition, when pouring warmed resin, it is necessary to comprise so that a circuit board may not be deform | transformed or damaged with a heat | fever.

  By producing the battery pack in this manner, a battery pack with high quality and high productivity that is good in volumetric efficiency and does not cause pressure on the electrode terminals or increase in battery thickness can be obtained.

  Hereinafter, the present invention will be specifically described by way of examples.

The battery in the heat-sealed portion after the battery pack designed to have a battery thickness of 3.97 mm was manufactured using the test battery pack configured as shown in FIG. 2 and the top cover and the exterior material were heat-sealed. The thickness was measured and compared. The test battery pack has (1) notch on each of the upper and lower holders (2) notch on the upper holder, no notch on the lower holder (3) no notch on the upper holder, notch on the lower holder (4) Ten pieces are prepared for each combination of the upper holder and the lower holder without notches.

  The battery thickness is designed to be 4.00 mm at the maximum, and whether the test battery pack after heat fusion is good or bad is determined. Table 1 below shows the measurement results of the battery thickness after heat-sealing of the test battery pack.

  From the above results, some of the upper and lower holders that did not have cutouts exceeded the maximum battery thickness design, but those that had cutouts in the upper and / or lower holders. None exceeded the design maximum. In particular, those having notches in both the upper holder and the lower holder were uniform in terms of variation in battery thickness.

  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.

  Moreover, the Al foil used for the hard laminate material and the soft laminate material is not limited to the above, and various materials can be used. In particular, in the hard laminate material, hard aluminum materials of 2000 series, 5000 series, and 6000 series can be used in addition to JIS standard 1100H.

It is sectional drawing which shows the structure of the conventional battery pack. It is a schematic diagram which shows the structure of the battery pack to which this invention is applied. It is a schematic diagram which shows the structure of the battery element used by this invention. It is a schematic diagram which shows the structure of the battery cell used by this invention. It is sectional drawing which shows the structure of the laminate film material used by this invention. It is a schematic diagram which shows the structure of the top cover and battery cell which were used in the conventional battery pack. It is a schematic diagram which shows the structure of the upper holder of the top cover used by this invention. It is a schematic diagram which shows the mode of the electrode terminal derivation | leading-out part of a battery cell at the time of fitting the top cover used by this invention. It is a schematic diagram which shows the structure of the lower holder which comprises the top cover used by this invention. It is a schematic diagram which shows the mode of the routing of the electrode terminal in a battery pack at the time of using this invention. It is a schematic diagram which shows the structure of the upper holder, lower holder, and battery cell using this invention. It is a schematic diagram which shows a mode that the top cover produced using this invention is fitted to a battery cell. It is a schematic diagram which shows a mode that the top cover produced using this invention is fitted to a battery cell. It is a schematic diagram which shows a mode that the top cover produced using this invention is fitted to a battery cell. It is sectional drawing which shows a mode that the top cover produced using this invention is fitted to a battery cell.

Explanation of symbols

2, 12 ... Electrode terminals 3, 13a, 13b ... Sealant 4, 14 ... Top cover 4a, 14a ... Upper holder 4b, 14b ... Lower holder 5 ... Exterior material 6 .... -Battery element 9 ... Circuit board 10 ... Battery pack 11 ... Laminate material 11a ... Hard laminate material 11b ... Soft laminate material 15 ... Rear cover 16 ... Battery cell 17 ... Projection wall 18 ... Circuit board 20 ... Battery element 21 ... Positive electrode 22 ... Negative electrode 23a, 23b ... Separator 24 ... Polymer electrolyte 30 ... Metal layer 31 ... Outer resin layer 32 ... Inner resin layer 33, 34 ... Adhesive layer

Claims (4)

A square or flat battery element is housed in a hard exterior material having first and second openings at both ends, and the first and second openings are covered by first and second covers, respectively. A circuit board to be joined to the electrode terminal lead of the battery element is housed in the first cover fitted into the first opening,
The first cover includes an upper holder manufactured by resin molding that holds the circuit board from the side opposite to the battery element side of the circuit board, and a lower part manufactured by resin molding that is disposed on the battery element side of the circuit board. In a square or flat battery pack having at least a holder, and the upper holder and the lower holder are bonded or bonded by mechanical engagement means,
The upper holder, that have a first notch portion facing the electrode terminal lead-out portion where the electrode terminals are led out from the battery device
Batteries pack. The lower holder includes a bottom surface portion facing the battery element with one main surface facing,
Of the one end surface of the bottom surface portion, the portion facing the electrode terminal lead-out portion has a second notch,
The battery pack according to claim 1, wherein a third notch is provided in a portion facing the second notch of the other end surface facing the one end surface of the bottom surface portion . The lower holder, which has a projection portion for supporting the circuit board to the circuit board side of the bottom portion, which have a lower projection wall height than the protrusions along the longitudinal direction of the lower holder <br/> claims Item 3. The battery pack according to Item 2. The battery pack according to <br/> claim 2 in which the electrode terminals are bent so as to be accommodated in the notches provided on the lower holder in the first cover are fitted.

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