JP2003282038A - Battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery pack in which the battery and a circuit board or the like are integrated by resin mold by improving bonding characteristic between the battery and the resin. <P>SOLUTION: On a desired site on a sealing plate 23 of a secondary battery 2, an adhesive 69 having a superior bonding characteristic to the metal is coated, and the resin is filled between the circuit board 3 and the secondary battery 2 arranged on the sealing plate 23, and a primary mold body 11 is formed. When the adhesive 69 is coated also on the bottom face of the battery can 22, the bonding characteristic between the secondary mold body 12 and the battery can 22 is improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery pack in which a circuit board, a terminal board, etc., which constitutes a battery protection circuit, external connection terminals, etc., are integrally fixed to a secondary battery by a resin, and in particular, The present invention relates to a battery pack having improved joint strength with a battery.

[0002]

2. Description of the Related Art The miniaturization and thinning of mobile electronic devices such as mobile phones and PDAs, as well as the advancement of high functionality, are remarkable, and correspondingly, the batteries serving as power sources are required to be small, thin and have high capacity. Has been done. Lithium-ion secondary batteries are effective as batteries that enable small size and high capacity. Among them, flat prismatic ones are suitable for thinning devices, and can be used repeatedly as portable batteries for portable electronic devices. The application is increasing.

Since the lithium ion secondary battery has a high energy density and uses a flammable organic solvent as an electrolytic solution, consideration for safety is important. It is necessary to ensure safety so as not to damage the human body or equipment even if an abnormality occurs for some reason. For example, when a short circuit occurs between the positive electrode terminal and the negative electrode terminal of the battery for some reason, an excessive short-circuit current flows in the battery having high energy density, Joule heat is generated due to internal resistance, and the temperature of the battery rises. When the temperature of the battery rises, the reaction between the positive electrode active material and the electrolytic solution, vaporization and decomposition of the electrolytic solution may occur, and the gas pressure inside the battery may rise rapidly, which may cause the battery to burst or ignite. Not only the above-mentioned external short circuit causes the battery to fall into a high temperature state, but also when the secondary battery is overcharged, the portable electronic device with the battery placed near the heater, or left in the car parked in the hot sun. And so on.

The cause of an abnormal state of a battery is electrical,
Various factors such as mechanical and thermal factors are considered, and non-aqueous electrolyte secondary batteries such as lithium-ion secondary batteries prevent the battery from entering an abnormal state and also when it enters an abnormal state. A function is provided to prevent the situation from becoming dangerous. The function of the battery itself is to prevent excessive reaction of the active material and electrolyte of the electrode plate, and the polyolefin microporous film used as a separator softens and closes its pores at abnormally high temperatures. It has a shutdown function. Further, in a cylindrical lithium ion secondary battery, a PTC (Positive Thermal) connected in series with an input / output circuit at a sealing portion is used.
A protective function for limiting an excessive current due to an external short circuit is provided by disposing a Coeffient) element. In a battery in which the PTC element is not provided in the battery, it is indispensable to connect a PTC element or a thermal fuse as an external circuit component by wiring and further to provide a battery protection circuit for protecting the battery from overcharging or overdischarging. It is a requirement, and these components are generally housed in a pack case together with a secondary battery to form a battery pack.

However, since the resin molding die for forming the pack case is expensive to manufacture and requires a long development period, it should be used as a battery pack for portable electronic devices in which new models are frequently introduced. Is difficult. Also,
As described above, in order to configure a battery pack that can be made smaller and thinner in portable electronic devices, there is a limit to the wall thickness that can be molded by resin molding, and a battery pack that uses a resin molded pack case as an outer case is thin. There is a limit to conversion.

[0006] In order to prevent the battery pack from being disassembled to be used incorrectly or for the sake of interest, the battery pack may be constructed so that it is difficult to disassemble or that the disassembly can be understood. It is important for ensuring safety. Also,
Considering that it is applied to portable electronic devices, it is required to have a robust structure that can withstand shock and vibration due to a drop or the like and moisture resistance of electronic circuit parts. In order to realize such a structure that is hard to disassemble, is robust, and has moisture resistance, it is conceived that a circuit board that constitutes a battery protection circuit and the battery are integrated with a resin mold.

A battery pack made of the resin mold described above is known as disclosed in Japanese Unexamined Patent Publication No. 2000-315483. A battery pack and a circuit board connected by a connecting member are arranged in a mold to form a circuit. There is disclosed a configuration in which a substrate is resin-sealed and fixed on a battery or a pack case (battery lid), or a circuit substrate and a battery are resin-sealed.

[0008]

When a circuit board is integrated with a secondary battery by resin filling, it is necessary to bond the resin to the circuit board and the secondary battery. However, since the resin to be filled and molded does not bond to the metal surface, it is necessary to integrate the resin so that the resin does not separate due to the resin flowing into the uneven portion and solidifying. The circuit board has many uneven parts such as electronic parts and lead plates, and the filled resin is easy to engage, but the secondary battery has few uneven parts even at the sealing part, and is formed of a smooth metal member. It has a low affinity with the resin and is easily peeled off after the filled resin is solidified, and the integration with the circuit board becomes unstable. Therefore, when the battery pack is applied to a portable electronic device or the like that is inevitably subject to vibration and impact, there is a possibility that a problem may occur due to the resin peeling off from the secondary battery.

In the prior art disclosed in the above publication, when the circuit board is integrated with the secondary battery, the resin does not bond to the secondary battery. Therefore, the circuit board is attached to the battery with a double-sided tape to compensate for it. After the attachment, the circuit board is wrapped and the resin is molded on the secondary battery. The molded resin engages with the irregularities of the circuit board, and the circuit board is bonded to the secondary battery with a double-sided tape, so the resin and the secondary battery are joined together. Deterioration,
When the adhesive strength is lowered due to the temperature rise, the bonding state between the resin and the battery is weakened, and there is a risk that the resin will peel off and the circuit board will separate from the secondary battery when it receives an impact such as a drop. When the resin is molded so as to enclose the battery, a state in which the battery is enclosed in a resin case is obtained, but the thinness that is a feature of the flat prismatic battery is impaired, and the miniaturization targeted by the present invention is achieved. However, it is difficult to realize a thin battery pack.

It is an object of the present invention to provide a battery pack capable of improving the degree of bonding of the resin to the secondary battery when the circuit board is integrated with the secondary battery by filling the resin. is there.

[0011]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a secondary battery in which a metal battery can containing a power generating element is sealed by a metal sealing plate, and a circuit board is made of resin. In the battery pack integrated by the filling molding of, prior to the filling molding of the resin, an adhesive having a good metal bonding property is applied to at least a required portion of the sealing plate and the battery can. Since the applied adhesive is bonded to the metal surface and the resin filled therein is bonded to the adhesive, the degree of bonding between the secondary battery and the resin is improved. Therefore, the resin can be bonded to the sealing plate of the secondary battery or the bottom surface of the battery can, which is a smooth surface. Further, since the circuit board has many uneven portions, the resin is easily engaged with the circuit board, but if an adhesive is further applied, the integration with the secondary battery can be made more reliable.

Further, when the adhesive is applied to the sealing plate, the adhesive is applied mainly to the joint portion of the sealing plate with the battery can and the joint portion with the battery constituent elements formed on the sealing plate. Then, even if there is a risk of liquid leakage due to pinhole-shaped gaps in the welded part or the sealing part with the gasket,
Since the pinholes are blocked by the adhesive, it is possible to ensure the hermeticity of the secondary battery in response to the pinholes that may occur. In order to be able to cope with such liquid leakage, it is preferable that the adhesive has a property of high resistance to dissolution in an electrolytic solution.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiments described below are examples of embodying the present invention and do not limit the technical scope of the present invention.

The present embodiment is an example in which a flat prismatic lithium-ion secondary battery is integrated with a circuit board having an external connection terminal and a battery protection circuit by resin filling to form a battery pack applied to a mobile phone. Is shown. The battery pack applied to mobile phones is small, lightweight, thin, and has a high energy density that supports high functionality, mechanical strength that can withstand impacts such as drops that are inevitable as mobile devices, a structure that is difficult to disassemble, and a short circuit. It is required to have a safety function of protecting the secondary battery from overcharge, high temperature, etc., and the battery pack shown below is configured to meet these requirements.

FIG. 1 shows an external view of a battery pack 1 according to this embodiment. One end face has a positive electrode terminal and a negative electrode terminal.
The external connection terminal 6 consisting of the temperature detection terminal is exposed to the outside,
A submerged seal 9 is attached on a test terminal 30 described later to form a flat asymmetrical shape. Hereinafter, the details of the main components will be described, and the manufacturing procedure will be described.

2 (a) and 2 (b) show the structure of the secondary battery 2 applied to the battery pack 1, which is configured as a flat prismatic lithium ion secondary battery. In this secondary battery 2, a power generating element is housed in a battery can 22 made of aluminum and formed in a bottomed tubular shape having an oval cross section, and an opening end thereof is laser-welded to a sealing plate 23. It is sealed. A rivet 25, which serves as a battery negative electrode by being insulated by an upper gasket 24a and a lower gasket 24b, is attached to the center of a sealing plate 23 that is joined to the battery can 22 and serves as a battery positive electrode. A part of the sealing plate 23 is formed as a clad plate obtained by laminating foil-like plates, and an opening is formed in the clad plate forming portion to form the safety valve 20. This safety valve 20 prevents the battery can 22 from rupturing when a gas is generated in the battery can 22 due to a temperature rise or the like and the internal pressure abnormally rises, the thin plate portion is broken to release the abnormal internal pressure to the outside. To do. In addition, the sealing plug 2 provided on the sealing plate 23
Reference numeral 7 closes the opening for injecting the electrolytic solution into the battery can 22, which is press-fitted into the opening formed in the sealing plate 23 after the injection of the electrolytic solution and welded to the sealing plate 23. On both sides of the sealing plate 23, eyelet-like engagement members 26 are welded and joined.

A sealing plate 23 for the secondary battery 2 is provided.
The adhesive 69 is applied to the side and the bottom surface of the battery can 22. The application of the adhesive improves the degree of bonding between the secondary battery 2 and the resin filled on the sealing plate 23 and the bottom surface of the battery can 22 in the later-described primary mold and secondary mold. As shown in FIG. 4, a plurality of constituent elements are joined and arranged on the sealing plate 23. Therefore, as shown in FIG. 3A, the application site is specified and the adhesive 69 (shown with diagonal lines) is applied. Is applied. If the adhesive 69 is applied to the periphery of the sealing plate 23, that is, the welded portion with the battery can 22, the periphery of the rivet 25 and the upper gasket 24a, and the periphery of the discharge port 20a of the safety valve 20, the adhesive 69 will be a liquid. The effect of preventing leakage can also be obtained. That is, when a slight amount of water adheres to the welded portion, a pinhole may be generated in the welded portion due to evaporation of water during welding. In addition, the rivet 25 is sandwiched between the upper and lower gaskets 24a and 24b with the sealing plate 23 interposed therebetween.
Even when the screws are fastened to each other, fine gaps may occur due to dust adhesion, defective parts, or the like. Since such pinholes and the like may occur with a probability of about 1 / 1,000,000, it is possible to prevent liquid leakage even if a pinhole should occur, by applying the adhesive 69 to the portion that may cause such a possibility. The effect can be obtained. On the bottom surface of the battery can 22, as shown in FIG.
(Hatched line) is applied and the oval insulator 14 is attached to the central portion.

As the adhesive 69, one having a high adhesiveness with a metal and having an electrolytic solution melting resistance is preferable in consideration of prevention of liquid leakage. In the present embodiment, Cemedine S manufactured by Cemedine Co., which is a room temperature moisture-curable elastic adhesive, is used.
X720 was used. The cured adhesive 69 has good bondability with the resin filled therein, and bonds to the resin molded and filled.

Further, the secondary battery 2 to which the adhesive 69 is applied
As shown in FIGS. 4 (a) and 4 (b), a resin sheet 40 made of a porous material is adhered to the sealing plate 23 to cover the discharge port 20 a of the safety valve 20 and the sealing plug 27 is insulated. Paper 21
To adhere.

In the secondary battery 2 in which the applied adhesive 69 is hardened, as shown in FIG.
The one connecting piece 10a of the groove 10 is welded. A heat insulating sheet 16 is attached to the upper surface of the thermal fuse 10 to prevent the thermal fuse 10 from being blown out at the time of resin filling described later. The other connecting piece 10b of the thermal fuse 10 is arranged on the insulating paper 21 and is joined to one end of a negative electrode lead plate 5 described later by spot welding. Also, the thermal fuse 1
0 and the sealing plate 23 are coated with a heat conductive adhesive so that the heat of the secondary battery 2 is easily transferred to the thermal fuse 10.

As shown in FIG. 5A, the circuit board 3 is attached to the secondary battery 2 to which the thermal fuse 10 is attached by the positive electrode lead plate 4 and the negative electrode lead plate 5.
The circuit board 3 constitutes a protection circuit that protects the secondary battery 2 from overcharge, overdischarge, and overcurrent. As shown in FIG. 5B, the external connection terminal 6 and the test terminal 30 are provided on one surface of the circuit board 3.
And an electronic component 31 such as an integrated circuit component is mounted on the other surface, and positive electrode soldering lands 32 and negative electrode soldering lands 33 for connecting to the secondary battery 2 are formed on both sides. One end of the positive electrode lead plate 4 is soldered to the positive electrode solder land 32, and one end of the negative electrode lead plate 5 is soldered to the negative electrode solder land 33. The other end of the positive electrode lead plate 4 is spot-welded to the plate surface of the sealing plate 23, and the other end of the negative electrode lead plate 5 is spot-welded to the other connecting piece 10b of the thermal fuse 10. In this connection state,
Since the circuit board 3 is oriented in a direction orthogonal to the plate surface of the sealing plate 23, the positive and negative lead plates 4 and 5 are bent to form the plate of the circuit board 3 as shown in FIG. 5B. A gap is provided between the surface and the plate surface of the sealing plate 23, and shaping is performed in parallel. In this way, the circuit board 3 is connected to the secondary battery 2 to form the resin filling target 7 as shown in FIG.

The gap between the secondary battery 2 and the circuit board 3 of the resin-filled object 7 is filled and molded with resin to integrate the secondary battery 2 and the circuit board 3. The resin-filled object 7 is housed in the lower mold 36 of the primary molding die 35 configured as shown in FIG. 6, the upper mold 37 is closed by the upper mold 37, and the gate 44 provided in the upper mold 37 The melted resin is injected, and as shown in FIG. 7, the resin is filled into the gap between the secondary battery 2 and the circuit board 3 to form the primary mold body 11.
The resin injected between the secondary battery 2 and the circuit board 3 also wraps around the electronic components 31 mounted on the circuit board 3 and the lead plates 4 and 5 for the positive and negative electrodes to the circuit board 3. Engaging member 2 that is joined and joined on the sealing plate 23 of the secondary battery 2
It also wraps around the undercut portion of 6 and is joined to the sealing plate 23. In addition, a portion of the lower mold 36 that contacts the live part (for example, the external connection terminal 6) of the resin-filled object 7 is subjected to an insulation treatment such as an alumite treatment, and the secondary battery 2 is formed by the mold.
To prevent short circuit.

By this resin filling molding, the electronic component 31 mounted on the circuit board 3 is covered with the resin, and the insulation and moisture resistance are improved. Further, the resin is bonded to the adhesive 69 applied on the sealing plate 23, and the resin also enters the concave-convex portion and the undercut portion of the engaging member 26 to fix the resin to the secondary battery 2, The integration of the secondary battery 2 and the circuit board 3 is ensured.

After the filled resin is cured, it is taken out from the primary molding die 35, and can be taken out from the lower die 36 as an intermediate finished product 8 as shown in FIGS. 7 and 10 (b). The intermediate finished product 8 can be formed into the battery pack 1 by applying an outer coating on the periphery thereof. The exterior coating is applied by adhering the secondary mold and the winding sheet.

In the secondary molding, the intermediate finished product 8 is placed in a secondary molding die 46 as shown in FIG.
A resin is molded at a required portion of the intermediate finished product 8. The lower mold 47 of the secondary molding die 46 is formed with a recess 50 for accommodating the intermediate finished product 8, and one side wall surface of the recess 50 is for three external connection terminals that are biased inward. A protrusion 51 and a test terminal protrusion 52 are provided, and a bottom face protrusion 54 that is urged to move inward is provided on the other side wall surface facing each other.
The intermediate finished product 8 is arranged in the recess 50, and the external connection terminal projection 51, the test terminal projection 52, and the bottom surface projection 54.
The external connection terminal protrusion 51, the circuit board 3
The test terminal projections 52 are pressed into contact with the test terminals 30, and the bottom projection 54 is in the center of the insulator 14 attached to the bottom surface of the secondary battery 2. Press on the part. In the lower die 47 as well as in the primary molding die 35, an insulating treatment such as an alumite treatment is applied to a portion (external connection terminal protrusion 51, test terminal protrusion 52) that contacts the live part of the intermediate finished product 8. Thus, the short circuit of the secondary battery 2 due to the lower mold 47 is prevented.

In this state, the lower mold 47 is closed by the upper mold 48,
Resin is filled into the secondary molding die 46 from the gate 53 provided on the upper die 48. The resin is injected from the four gates 53 into the secondary molding die 46, as shown in FIGS.
As shown in (c), the external connection terminals 6 and the test terminals 30 of the intermediate finished product 8 are exposed to the outside, and the insulator 14
Of the secondary battery 2 is exposed to the outside, the primary molded body 11 and the circuit board 3 are covered, and the upper molding portion 17 fixed on the sealing plate 23 of the secondary battery 2 is formed. A lower molding portion 18 is formed by wrapping around the periphery of the upper molding portion 1 and fixed to a predetermined thickness.
The secondary molded body 12 in which the connection molding portion 19 that connects the lower molding portion 7 and the lower molding portion 18 at the side surface corner of the secondary battery is formed is molded. As shown in FIG. 11, the connection molding portion 19 is formed of resin so as to cover a 90 ° portion on one side of the arc side surface of the secondary battery 2 having a cross section of an oval shape and form a right angle cross section. It

Also in the formation of the secondary molded body 12, since the adhesive 69 is applied in advance to the bottom surface of the battery can 22, the resin is bonded to the bottom surface of the battery can 22, which is a flat surface, so that the secondary molding is performed. Resin molding is reliably performed on the intermediate finished product 8 of the body 12.

A step portion 38 is formed on the peripheral surface of the upper molding portion 17 near the secondary battery, and the side peripheral surface of the secondary battery 2 is wound around the stepped portion 38 as a sticking positioning line to form a wound sheet. 1
3 is wrapped around. After that, the operation state is inspected using the test terminal 30, and the submerged seal 9 is attached to the recessed portion around the test terminal 30 for the inspection-accepted product, and the battery pack 1 as shown in FIG. 1 is formed. .

In the battery pack 1 thus formed, the flat shoulders on one side are formed at arc corners where arcs on both sides of the secondary battery 2 appear on the surface, and the shoulders on the other side are connected. Since the molded portion 19 is formed in a rectangular corner, the external connection terminal 6 is formed in an asymmetrical position, and therefore the reverse loading to the device can be prevented. Further, the arcuate corner corresponds to the rounded shape of the corner of the device case, so that the device can be stored in the device without forming a useless space. Further, since the thickness of the battery pack 1 is obtained by only winding the winding sheet 13 around the peripheral surface of the secondary battery 2, the thickness of the secondary battery 2 is slightly increased, and the battery pack 1 is made thinner. Is being pursued.

With respect to the battery pack 1 manufactured as described above, a free drop test in which a drop height of 1.5 m was dropped onto concrete for 2 cycles on each of 6 sides, and a drop height of 1.0 m was dropped onto an iron plate 50 times. Conduct a random drop test to see the electrical characteristics by dropping the product 200 times to see the mechanical performance, and further apply a heat shock test in which a temperature change of -40 to 80 ° C is applied multiple times, and a vibration test in which vibration in three directions is applied. A terminal strength test for applying a load to the external connection terminal was performed. After the test, the battery pack 1 was attached to the device, and it was verified whether or not there was any abnormality in attachment, whether it worked normally, or whether there was deformation or looseness. As a result, no damage was observed even after each test, demonstrating that the structure is robust.

Further, the influence on the secondary battery 2 by the filling and molding of the resin having a temperature exceeding 200 ° C. or the damage of the thermal fuse 10 arranged at the resin filling portion was verified, but no abnormality occurred. .

Further, in order to verify the state when the completed battery pack 1 is disassembled, an attempt is made to disassemble the battery pack, but the disassembly is extremely difficult as compared with a structure using a general pack case. When the primary mold body 11 is destroyed, the engaging members 26 provided at both ends of the sealing plate 23 are destroyed, and the positive and negative lead plates 4 and 5 and the connecting portions present in the filled and molded product are not removed. It was destroyed and put in a state where it can be easily determined that it was disassembled.

The accuracy of the finished external dimensions is such that the size of each part falls within an error range of ± 0.1 to 0.2 mm, and the size from the bottom surface to the external connection terminal 6 where accuracy is particularly required is within the same error. Yes, it was confirmed that the connection with the equipment would not be hindered.

Further, when the device loaded with the battery pack 1 having the above-mentioned structure is left on a heater and exposed to a high temperature condition such as heating, the secondary battery 2 has an internal pressure due to gas generation due to the high temperature. It rises abnormally. When the increase in the internal pressure exceeds the operating pressure of the safety valve 20, the thin plate portion is broken and the internal pressure is externally discharged from the discharge port 20a to prevent the secondary battery 2 from bursting. The discharge port 20a is covered with a porous resin sheet 40, and the outer surface of the discharge port 20a is covered with the primary molded body 11a.
Since the gas containing the ejected electrolytic solution passes through the resin sheet 40 and both ends thereof are exposed to the outside, the coating of the winding sheet 13 is pushed open from the end surface covered with the winding sheet 13. It is released to the outside. At this time, most of the liquid component of the electrolytic solution is stopped in the resin sheet 40 and only the gas component is released to the outside, so that the resin sheet 40 has an effect of suppressing leakage of the electrolytic solution.

[0035]

As described above, according to the present invention, when a secondary battery and a circuit board are integrated by resin molding to form a battery pack, an adhesive is applied to a portion to be filled with resin. Since the filled resin can be securely engaged with the secondary battery, it is robust enough to withstand a shock such as dropping as a battery power source suitable for small portable electronic devices, It is possible to provide a battery pack having a structure that prevents the battery pack from being used. In addition, liquid leakage can be prevented even if a pinhole or the like should occur at the welding site due to the application of the adhesive.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external appearance of a battery pack according to an embodiment.

2A is a plan view and FIG. 2B is a cross-sectional view showing a configuration of a secondary battery according to an embodiment.

FIG. 3 is a plan view showing (a) an application state of an adhesive to a sealing plate of a secondary battery, and (b) a bottom view showing an application state of an adhesive to a bottom surface.

4A is a plan view and FIG. 4B is a sectional view showing the arrangement of members on a secondary battery.

FIG. 5 is a perspective view showing how the circuit board is attached to the secondary battery.

FIG. 6 is a perspective view showing a configuration of a primary molding die.

FIG. 7 is a sectional view showing a state in which a primary mold body is formed.

FIG. 8 is a perspective view showing a configuration of a secondary molding die.

FIG. 9 is a sectional view showing a state in which a secondary mold body is formed.

FIG. 10 is a perspective view sequentially showing the formation state at each stage of the manufacturing process.

FIG. 11 is a cross-sectional view showing a state in which a connection molding portion is molded into a secondary battery.

[Explanation of symbols]

1 battery pack 2 Secondary battery 3 circuit board 11 Primary mold body 12 Secondary mold body 69 adhesive

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Kataoka             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Koichi Toriyama             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H040 AA14 AA34 AS13 AY08 DD08                       JJ03

Claims (4)

[Claims] 1. A battery pack in which a circuit board is integrated with a secondary battery formed by sealing a metal battery can containing a power generating element with a metal sealing plate by resin filling molding. A battery pack, characterized in that, prior to molding, at least the required parts of the sealing plate and the battery can are coated with an adhesive having a good metal bonding property. 2. The battery pack according to claim 1, wherein the adhesive has a property of high resistance to dissolution in an electrolytic solution. 3. The battery according to claim 1, wherein the adhesive is mainly applied to a joint portion of the sealing plate with the battery can and a joint portion with a battery constituent element formed on the sealing plate. pack. 4. The battery pack according to claim 1, wherein the adhesive is applied to the bottom surface of the battery can.