JP5142479B2 - Unit cell and method of manufacturing a battery pack provided with the same - Google Patents

Description

  The present invention relates to a battery pack having a unit cell including an outer can made of an aluminum-containing material, and a method for manufacturing the battery pack.

The battery pack is used as a driving power source in an electronic device such as a mobile phone, and includes a unit cell and a protection circuit board as components. The protective circuit board is an electronic component that is interposed between the unit cell and the external device.
FIG. 6 is an exploded perspective view showing the configuration of the battery pack. The unit cell 910 is made of a metal material, and in order to ensure the insulation of the unit cell, a protective circuit board, an external extraction electrode, and the like are molded with resin on the top, and a resin body 960 is disposed on the bottom, and an outer can The outer peripheral surface of 910 is covered with an insulating sheet 950 or the like (for example, Patent Document 1).

The unit cell 910 includes a bottomed cylindrical outer can and a sealing plate that seals the opening of the outer can. The outer can is often made of a lightweight and malleable metal material such as aluminum (Al) or an Al alloy, which makes it possible to reduce the size and size of the battery pack.
JP 2003-282036 A

  However, the resin body 960 disposed on the bottom portion includes a main body portion 960a and an engaging portion 960b, and the engaging portion 960b is integrally covered with the outer can 910 by the insulating sheet 950. Thereby, the battery pack 900 becomes thicker by the thickness W of the engaging portion 960b at the bottom. Further, the height (length in the X direction) of the battery pack 900 increases by the thickness D of the main body 960a. From these points, it is considered that there is still room for improvement in the battery pack 900 with respect to the reduction in thickness and size.

 The present invention has been made in view of the above problems, and an object of the present invention is to provide a unit cell that can ensure insulation and contribute to improvement in thinness and downsizing, a battery pack including the unit cell, and a method for manufacturing the unit cell. .

For the preparation method of the unit cell, the anode relative to the outer surface of the outer can body of the bottomed tubular made of aluminum-containing material, comprising a bottom, and toward the opening side end portion from the end of the bottom side Oxidation step for performing an oxidation treatment, and after the oxidation step, an exterior can manufacturing step for preparing an exterior can by removing the opening side edge of the exterior can body, and after the exterior can manufacturing step, A sealing step of sealing the opening of the outer can with a sealing plate is performed.

Further, in the sealing step, the sealing plate is arranged so as to be in contact with the inner peripheral surface of the outer can, and a portion of the contact portion between the sealing plate and the outer can that faces the outer space is welded. desirable.
And after the said oxidation step, you may use the method of attaching | subjecting a predetermined pattern or a character to the exterior can part which performed the anodizing process by an etching or printing.

  Also, a unit cell manufacturing step of manufacturing a unit cell by the above-described unit cell manufacturing method, and a cover body disposing step of disposing a cover body so as to cover the top surface of the unit cell on which the sealing plate is arranged A protective circuit board that electrically protects the unit cell from overcharging or overdischarging in the cover body disposing step, electrically with respect to each of a positive electrode terminal and a negative electrode terminal of the unit cell. A battery pack is produced by screwing and joining to the sealing plate so as to be connected, and by connecting the positive electrode terminal and the negative electrode terminal to the protection circuit board by the tightening force of the screw joint. To do.

In the manufacturing method according to the present invention, the edge on the opening side of the outer can body that has been anodized on the bottom surface on the outer surface and the region from the bottom side end to the opening side end is provided. Removed to make an outer can. Thereby, the opening part end surface in which the film by an anodizing process does not exist at all can be easily formed in the produced exterior can. Therefore, the sealing plate and the outer can can be welded at the end face of the opening, and the welding strength is not deteriorated.

  In particular, the sealing plate is placed in contact with the inner peripheral surface of the outer can, and the alumite treatment is applied to the end of the outer can opening by welding the portion facing the outer space of the contact portion. However, the welding strength does not deteriorate. If the sealing plate and the outer can are welded by performing a welding process from a substantially vertical direction to the side wall of the outer can, the end portion of the opening of the outer can is not alumite treated so as not to deteriorate the welding strength. It is necessary to keep it. For this reason, it is necessary to separately perform a treatment for ensuring insulation against the non-alumite treatment portion in the welded outer can, but in the present invention, it is not necessary to perform the treatment, which is useful in terms of manufacturing cost. .

Hereinafter, the best mode of the battery pack according to the present invention will be described with reference to the drawings.
1. Overall Configuration of Battery Pack A battery pack according to this embodiment will be described with reference to FIG. FIG. 1 is an exploded perspective view of the battery pack 1.
The battery pack 1 includes a lithium ion battery (hereinafter referred to as “unit cell”) 10, a cover body 20 provided so as to cover one end surface of the unit cell 10, and a protection circuit board 30.
(1-1) Unit cell 10
The unit cell 10 has a thin rectangular parallelepiped shape, an outer can 11 having an opening, an electrode body (not shown) that is housed inside and serves as a power generation element, and a sealing plate that seals the opening of the outer can 11. 12. The outer can 11 and the sealing plate 12 are laser welded.

  The outer can 11 has a thin three-dimensional shape with the X direction as the longitudinal direction, and has a height H (length in the X direction). The outer can 11 is formed by forming an Al portion 11b made of an aluminum (Al) alloy and an alumite coating 11a formed by oxidizing the Al alloy on the outer surface thereof, as shown in an enlarged view of a main part cutout. Further, as shown in FIG. 1, the alumite coating 11a is formed over the entire area of the bottom surface 11c of the outer can 11 and the region from the bottom surface 11c side end of the main surface 11d and side surface 11e to the end of the sealing plate 12 side. Has been. In addition, the bottom 11c side end means the end L11 of the main surface 11c and the side surface 11e and its vicinity, and the sealing plate 12 side end means the end L12 of the main surface 11c and the side 11e and its vicinity. Means part.

  The alumite coating 11a is formed by causing a chemical change (oxidation reaction) only in the surface portion of the Al portion 11b. As for the thickness of the alumite coating 11a, in order to ensure corrosion prevention and insulation, for example, about 25 to 30 μm and a maximum of 50 μm are required, but a resin plate is disposed on the bottom surface of the outer can as in the conventional embodiment. Compared with the form (see FIG. 6), the resin plate often requires a thickness of at least about 100 to 200 μm. By forming the alumite film 11a, the insulating property of the battery pack 1 can be maintained and the size can be reduced. It is clear that it contributes to realization. On the other hand, when the shape and size of the battery pack 1 are already defined by the specifications of the electronic device, the battery capacity in the unit cell 10 is increased by the thickness reduction that can realize the above-described downsizing. You can also. Thereby, the energy density of the battery pack 1 can be improved and high output can be achieved. In addition, the composition state (Al portion 11b) of the Al alloy is maintained without causing a chemical change except for the surface portion of the Al portion 11b.

  Moreover, in this embodiment, as shown in the drawing, the anodized coating 11a is formed on the main surface 11d and the side surface 11e of the outer can 11 from the bottom surface side (X direction positive direction side) to the sealing plate side (X direction negative direction side). It is formed over the entire area. Thereby, since the pressure resistance strength of the outer can 11 is also improved, the time-dependent expansion of the unit cell 10, particularly the expansion in the central region, can be suppressed by repeating charging and discharging.

Moreover, since the coloring of the alumite film 11a can be diversified depending on the conditions of the alumite treatment, it is possible to cope with the color tone of the cover body 20 and the like.
Further, a recycle mark print 13 is formed on the anodized film 11a using laser marking. The print 13 may indicate the rating and specifications of the battery pack 1. Since the printing is performed directly on the alumite coating 11a, it is not necessary to provide a separate member for displaying the printing portion, and it does not become an element that hinders thinning. The above printing may be formed not only by laser marking but also by printing using a hot stamp, silk printing, pad printing, or the like.

  Next, the sealing plate 12 is disposed on the top surface side opposite to the bottom surface side of the outer can 11. On the outer main surface of the sealing plate 12, a positive electrode and a negative electrode terminal project from the end in the Y-axis direction (not shown), and a nut portion is formed on each projecting top surface. A cover body 20 and a protection circuit board 30 which will be described later are joined through the nut portion. The sealing plate 12 is not anodized, and the unit cell 10 is in a state in which the anodized film 11a is not formed only in the region corresponding to the top surface.

The sealing plate 12 is joined in contact with the inner peripheral surface of the outer can 11, and the contact portion is welded. The welded part will be described later.
(1-2) Cover body 20
The cover body 20 is made of an insulating material (for example, a polyamide-based resin material), and has an end surface that is substantially the same shape as the main surface (on the YZ plane) of the sealing plate 12 as shown in FIG.

The cover body 20 is joined to the unit cell 10 by screwing using screws 43 and 44. A window portion (not shown) is provided on the end surface of the cover body 20, and external connection contacts (not shown) in the protection circuit board 30 are exposed outwardly from the respective window portions in the joined state. It is configured as follows. Screw caps 41 and 42 are fixed to the end surface where the window portion is formed at the outer edge portion in the Y-axis direction. The screw caps 41 and 42 are formed of the same insulating material as that of the cover body 20, and are provided with almost no step with respect to the end surface of the cover body 20. For the fixing, an adhesive, heat welding, ultrasonic welding, or the like can be used.
(1-3) Protection circuit board 30
The protection circuit board 30 is housed inside the cover body 20 and has a role of electrically protecting the unit cell 10 from overdischarge, overcharge, and the like. As shown in the figure, the protection circuit board 30 has a thin and substantially flat plate shape, and negative and positive connection leads 34 and 35 are respectively extended from both ends in the Y-axis direction of the board main body 30a. The connection leads 34 and 35 are provided with holes through which the screws 43 and 44 can be inserted, respectively.

On one main surface (X direction negative direction side) of the substrate main body 30a in the protection circuit substrate 30, the above-described external connection contacts are formed by laminating a metal material such as Au, Cu, or Ni in a foil shape. A plurality of electronic components 36, 37, and 38 including a heat sensitive element (for example, a PTC element or an NTC element) are mounted on the other main surface (X direction positive direction side) of the substrate body 30 a of the protection circuit board 30. ing. Note that the electronic device to be mounted is not limited to this.
2. Joining of Cover Body 20 (2-1) Joined State of Cover Body 20 As described above, the cover body 20 is joined to the unit cell 10 together with the protection circuit board 30, and the joined state will be described with reference to FIG. FIG. 2 is a partial cross-sectional view showing a state in which the cover body 20 is arranged so as to cover the top surface of the unit cell 10.

  The cover body 20 covers the protection circuit board 30 and is screwed and joined to the unit cell 10. In this joining, the sealing plate 12 is directly screwed to the positive electrode terminal 121 protruding from the main surface of the sealing plate 12, and the negative electrode terminal 122 similarly protruding is provided between the sealing plate 12 and the insulator. 123 is screwed in the inserted state. In addition, the height of each protruding terminal is the same, and the top surface is flat. Further, nut portions 121a and 122a are formed on the projecting top surface of each terminal toward the inside of the battery in the X-axis direction. In this embodiment, the two screws 43 and 44 are inserted into the holes 24 and 25 and the holes 34a and 35a and screwed into the nut portions 121a and 122a of the positive and negative bipolar terminals 121 and 122 of the unit cell 10, respectively. Let me. In this case, the positive and negative bipolar terminals 121 and 122 and the connection leads 34 and 35 can be reliably joined mechanically and electrically with a tightening force obtained by screwing the two screws 43 and 44 and the nut portions 121a and 122a. Figured.

On the other hand, since it is a connection method by screwing the screws 43 and 44, there is no need for dedicated equipment such as laser welding or ultrasonic welding. Therefore, in the manufacturing process, this embodiment has a great advantage in terms of equipment cost. In the case of insert molding or the like, the electronic elements to be mounted on the protective circuit board are limited in consideration of the molding temperature of the resin material, but this is not the case with the screw joint. Therefore, the degree of freedom of the electronic device to be used is also improved. Further, in the battery pack manufacturing process, the battery performance and the like are inspected at the final stage to detect defective products. In this embodiment, even if a defective product is detected, the screws 43 and 44 are tightened. By loosening and removing the cover body 20, partial repair such as replacement or repair of the protection circuit board 30 becomes possible.
(2-2) Covering Area of Cover Body 20 The cover body 20 covers one end surface of the unit cell 10 on which the sealing plate 12 is arranged (see FIG. 1), and its width (length in the Y direction) is an outer can. 11 (length in the Y direction) is almost the same length. In the present embodiment, since the alumite film 11a is formed on the entire bottom surface, main surface, and side surfaces (regions extending from the bottom surface to the opening) on the outer surface of the Al portion 11b, a sealing plate is disposed as shown in FIG. By simply covering only the top surface, that is, when the top surface of the outer can 11 and the cover body 20 are brought into contact with each other, the exposed portion of the Al alloy material is eliminated in the outer can 11 and the insulation of the battery pack 1 is ensured. The

  The insulation of the sealing plate 12 is ensured by the arrangement of the cover body 20. Since it is necessary to bond the sealing plate 12 to the opening of the outer can 11 after the electrode body is stored in the outer can 11, the Al alloy material is exposed without forming the alumite film 11 a in advance at the bonding portion (laser welding portion). It is necessary to let This is because the weld strength cannot be sufficiently secured when the alumite coating 11a is formed. Therefore, as shown in the enlarged view of FIG. 2, it is necessary that the alumite coating 11a is not formed on the region A necessary for welding, that is, the opening end face 11f of the outer can 11. Therefore, in the present embodiment, as described above for the outer can 11, the alumite film 11 a is formed over the entire bottom surface, main surface, and side surface, but the alumite film 11 a is not formed at all on the opening end surface 11 f. State.

The cover body 20 according to the present embodiment is set to a size that covers the top surface of the unit cell 10 where insulation is not ensured. That is, as shown in the enlarged view of FIG. 2, the position of the outer surface (Y direction side end surface) of the cover body 20 is set to substantially coincide with the position of the outer surface (Y direction side end surface) of the outer can 11. Moreover, although only the magnitude | size along the width direction (Y direction) of the armored can 11 is shown in this figure, similarly regarding the magnitude | size along the thickness direction (Z direction in FIG. 1) of the armored can 11 similarly. The cover body 20 and the outer can 11 are set to have substantially the same size. However, the length in the width direction and the thickness direction of the cover body 20 is not longer than the length of the outer can 11. Therefore, even if the cover body 20 is disposed on the top surface of the unit cell 10, the width and thickness of the battery pack 1 do not increase.
(2-3) Regarding welding according to the present embodiment The present embodiment is characterized in that the alumite coating 11a is formed on the opening side end portion of the outer surface of the outer can 11. 1 is useful in terms of reducing the thickness and thickness. Specifically, in this embodiment, as shown in the enlarged view of FIG. 2, in the opening portion of the outer can 11, the sealing plate 12 is in contact with the inner peripheral surface of the outer can 11. Welding is performed at a portion A facing the space, but if the sealing plate 12 is welded while being in contact with the opening end face 11f of the outer can 11, the welded portion is a B portion. At this time, in order not to deteriorate the welding strength in the B portion, an alumite film is not formed on the end portion 20a on the opening side on the outer surface of the outer can 11. That is, at the end 20a, the Al alloy material is exposed to the outside. Thus, when the area | region (for example, the said edge part 20a) in which the alumite film is not formed in the outer surface of the armored can 11 is provided, the said edge part 20a is shown in the cover body 20, as shown with the dashed-dotted line L1. In this case, the cover body 20 is larger than the outer can 11 by the length of d2 in the Y direction.

On the other hand, by performing welding according to the present embodiment, the portion A becomes a welded portion, and only the opening end surface 11f may be a non-alumite treatment portion, and the cover body 20 is formed so as to cover the end portion 20a. You don't have to. Therefore, the battery pack 1 in which the cover body 20 is disposed is realized to be smaller than the battery pack in which the cover body that covers the end portion 20a is disposed.
3. Method for Forming Alumite Coating 11a Therefore, a method for forming the outer can 11 provided with the alumite coating 11a will be described with reference to FIG. FIG. 3 is a perspective view showing a procedure until the outer can is anodized. This forming method includes a preliminary step performed before the anodizing process, an anodized processing step for performing the anodized process, and a cut step performed after the anodized process.
(3-1) Preliminary Step First, the preliminary step will be described with reference to FIG. Although described later, since the outer can used in this step and the outer can 11 used as a component of the unit cell 10 are different in size, the outer can in this step is referred to as the first outer can. 110.

The first outer can 110 is made of an Al alloy material and has a height H1 and a width W1, and the height H1 is larger than the height H of the unit cell as shown in FIG.
As shown in FIG. 3B, the plurality of first outer cans 110 are supported by a flat plate 210 and a support member 220 having a pair of extending portions that extend along a surface direction perpendicular to the main surface direction of the flat plate 210. Are installed in a jig 200 combined with The first outer can 110 is fixed by its inner surface being in contact with the support member 220, and is erected in a direction perpendicular to the main surface direction of the flat plate 210. The support member 220 extends with a length W2 along the width direction (Y direction) of the first outer can 110 in a standing state. The size of W2 is slightly larger than the width W1 of the first outer can 110, but is approximately the same size. When the first outer can 110 is standing, the support member 220 is slightly closed in the Y direction, and the first outer can 110 is supported by receiving the elastic force of the support member 220 expanding in the Y direction. The inner space of the first outer can 110 is sealed with a flat plate 210.

Next, the plurality of first outer cans 110 fixed to the jig 200 as described above are accommodated in the alumite treatment tank 300 into which the alumite treatment liquid 310 is injected as shown in FIG. The alumite treatment liquid 310 uses dilute sulfuric acid as an electrolyte. At this time, the entire outer surface of each first outer can 110 is immersed in the alumite treatment liquid 310.
(3-2) Anodized treatment step After the preliminary step, the anodized treatment is performed on the first outer can 110 immersed in the anodized treatment liquid 310. The alumite treatment is an anodic oxidation treatment in which Al or an Al alloy is used as an anode in an electrolytic solution to oxidize the surface to form an oxide film on the surface of the Al or Al alloy. In addition, the schematic schematic diagram of the alumite process which concerns on this embodiment is shown in FIG.

  A state in which the support member 220 is electrically connected in advance using the support member 220 as an anode and carbon current is applied to the negative electrode using carbon 320 is applied. Thereby, the 1st exterior can 110 which contacts support member 220 also functions as an anode, and electrolysis advances in electrolyte solution. An aluminum oxide film (alumite film) 11a is formed on the outer surface of the first outer can 110 functioning as an anode, and hydrogen is generated from the negative electrode. The material used for the negative electrode is not limited to carbon, and any material that contributes to the formation of an aluminum oxide film on the surface of the first outer can 110 using lead or the like is applicable. Moreover, the alumite film 11a with high quality performance can be formed by performing a preliminary process such as buffing and hairline, and a cleaning process such as degreasing and etching before the above process.

  The color of the alumite film 11a formed by the above method can be changed depending on the combination of the Al alloy, the type of the electrolytic solution, and the current waveform, and the electrolytic process is performed using an aqueous solution of Ni, Sn, Cu, Ag, or the like. Thus, another film can be formed on the alumite film 11a, and further coloring is possible. Therefore, the color tone of the first outer can 110 can be changed as appropriate according to the color tone of the cover 20 used when forming the battery pack 1 and the electronic device to which the battery pack 1 is mounted. It leads to improvement.

In addition to the alumite treatment, a hard alumite coating can be formed by alumite treatment such as performing alumite treatment at a temperature lower than the normal temperature to increase the current density. The hard anodized film is effective because it has higher durability than a normal anodized film.
(3-3) Cut step After the alumite treatment step, the anodized film 11a is formed, and the edge portion of the first outer can 111 having the height H1 is cut to a predetermined height H. For convenience of explanation, the first outer can after the alumite treatment is referred to as a second outer can 111, and the second outer can after being cut is referred to as a third outer can 11. This step will be described with reference to FIG. FIG. 5 is a perspective view showing a procedure for forming the third outer can 11.

  As shown to Fig.5 (a), the 2nd exterior can 111 after the alumite process step has the alumite film 11a formed in all the main surfaces, a side surface, and a bottom face. On the other hand, the opening end face 11g and the inner surface of the second outer can 111 are sealed in the inner space of the first outer can 110 by the contact between the first outer can 110 and the flat plate 210 in the anodizing step. An alumite film is not formed. However, as described above, since the alumite treatment is performed only with a simple jig, the alumite treatment liquid may enter between the flat plate 210 and the end face of the opening. In particular, in the manufacturing process of the unit cell, it is preferable from the viewpoint of manufacturing cost that the opening end face 11g of each second outer can 111 is inspected for the presence of the alumite coating and further the alumite coating is removed individually. There is no.

  Accordingly, as shown in FIG. 5B, the opening edge portion 111a of the second outer can 111 is cut and removed uniformly with respect to each second outer can 111, and the third outer can 11 that becomes a remaining portion is removed. Is used as a component of the unit cell 10. An alumite film is not formed on the opening end face 11f of the third outer can 11 and the welding strength is not deteriorated. The above cutting is performed such that the third outer can 11 has a predetermined height H and the opening end face is in the same plane direction (YZ plane) as the bottom surface of the third outer can 111.

  By performing this step, there is no need to perform a masking step or the like in advance so that the end face of the opening of the outer can 11 and the vicinity thereof are not anodized, and the step of removing the anodized film formed on the end face of the opening There is no need to do. Unlike the method of the present embodiment, for example, an outer can body having a predetermined height H is prepared in advance, an alumite film is formed so as to include the opening end face of the outer can body, and then the opening Even if only the alumite film formed on the end face is removed by polishing or the like, it is difficult to completely remove it. In such a case, the end face of the opening becomes rough due to the remaining alumite coating, resulting in deterioration of the welding strength of the sealing plate. In particular, in the situation where many unit cells 11 are manufactured, the accuracy of the polishing removal differs for each manufactured unit cell 11, which may hinder the yield improvement in the unit cell or pack battery manufacturing process. Even if peeling is performed using chemical means instead of physical means such as polishing, it is not easy to execute chemical means only on the end face portion of the opening. Further, in the case of polishing removal or the like, it is also conceivable that the surface direction of the formed opening end face does not coincide with the surface direction perpendicular to the height direction of the outer can 11.

  On the other hand, in this embodiment, since cutting and removal are performed, it is easy to make the alumite film completely absent from the end face of the opening, and the height adjustment of the manufactured outer can 11 is easy. It becomes. In particular, in the case of the unit cell 10 according to the manufacturing method of the present embodiment, the outer can 11 that can secure a strong welding strength with the sealing plate can be produced by a simple method as described above. Moreover, compared with performing the removal process, such as grinding | polishing separately, with respect to the outer can 11 after the alumite treatment step, the above-mentioned outer can 11 can be obtained simply by including a cutting process, so that the manufacturing cost can be reduced. It has a great advantage in terms.

In addition, printing is directly performed on the portion where the alumite coating 11a is formed, and the specifications and ratings of the battery are displayed. As the printing process, printing using a hot stamp, pad printing, laser marking, or the like can be applied as long as the alumite coating 11a can be directly printed. Note that the printing process is not only performed on the third outer can 11, but if the printing is performed on a portion excluding the opening edge portion 111 a to be cut, the second outer packaging before the cutting step is performed. You can go to the can.
4). Manufacture of the battery pack 1 The electrode body is housed inside the third outer can 11 manufactured through the above steps, and the opening of the third outer can 11 is sealed by the sealing plate 12 to form the unit cell 10. Then, the battery pack 1 is manufactured through a step of covering the sealing portion with the cover body 20.

  When the unit cell 10 is formed, the alumite coating 11a is already formed on the outer surface of the third outer can 11 to ensure insulation. Therefore, it is not necessary to attach a covering material such as an insulating sheet separately from the outer can 11, which contributes to reducing the thickness and size of the battery pack 1. In particular, in the manufacturing process of the battery pack 1, it is not easy to attach another member after forming the outer can. That is, in order to keep the appearance quality good, it may go through a complicated manufacturing process, and it is possible to use a simple method as in the present embodiment and further to eliminate the attaching process such as the insulating sheet. It is also preferable from the viewpoint of manufacturing cost.

After the unit cell 1 is formed, the cover body 20 is screwed and joined to the unit cell 10. The joining can be carried out relatively easily by positive and negative terminals of the unit cell 10, the protection control circuit 30, and the cover body 20 by a tightening force by screwing, and can be performed relatively easily. It is not what you need. Therefore, it is preferable in terms of time and cost in the manufacturing process of the battery pack 1. In addition, the performance inspection of the battery pack 1 is performed after the battery pack 1 is manufactured. If a portion covered by the cover body 20 by the inspection, for example, a defective portion is found in the protection circuit board 30, The cover body 20 can be easily detached from the unit cell 10 by weakening the tightening force. Therefore, if the cover body 20 is formed by molding a resin, it is impossible to use the entire battery pack 1 due to a partial failure. If there is, it is possible to eliminate the above-mentioned failure only by repairing or replacing the protection circuit board 30 or the like.
(Other matters)
All the outer cans according to the present embodiment have a surface shape in which the main surface and the side surface intersect perpendicularly from the bottom surface. However, the corner portion formed by the main surface, the side surface, and the bottom surface is an R-processed corner portion. It does not matter. At this time, the end portion of the side wall that is alumite-treated in the outer can includes the R-processed portion and is in the vicinity thereof. The same applies to the case where the outer can opening side is rounded.

  The third outer can 11 according to this embodiment is alumite-treated only on the outer surface thereof, but the inner surface may be alumite-treated. However, in that case, it is necessary that an alumite film is not formed on the inner surface of the third outer can 11 that contacts the sealing plate 12. Further, when the sealing by welding or the like is performed with a certain strength, the sealing plate 12 may be subjected to an alumite treatment. If there is no fear of affecting the electrode body or the like, alumite treatment may be performed even after the outer can 11 is sealed with the sealing plate 12.

In the present embodiment, the opening edge of the second outer can is cut and removed. For example, a method of scraping the edge or a method of peeling using a chemical means is used. However, since the same effect can be obtained, it is applicable.
In this embodiment, a lithium ion battery is used, but other sealed secondary batteries may be used. In addition, the outer can has an anodized coating over the entire bottom surface, main surface, and side surface. For example, an anodized coating is formed as an inspection portion for conducting a current inspection near the center of the battery pack. Even if a fine region that is not formed is formed, it is only necessary that the alumite film is formed on the entire outer surface of the outer can. Also, the material of the outer can 11 is applicable as long as it is made of a material containing Al. Moreover, if the contact part with a sealing board is remove | excluded, the said alumite film may be formed in the inner surface of an exterior can.

  The present invention is particularly useful for the production of a battery pack that can be reduced in thickness and weight, and can stably distribute power over a long period of time.

It is an expansion | deployment perspective view of the battery pack which concerns on embodiment. It is sectional drawing of the top part area | region of the battery pack which concerns on embodiment. It is a process perspective view before the alumite process of the exterior can which concerns on embodiment. It is a schematic diagram of the alumite process which concerns on embodiment. It is a process perspective view for producing the armored can provided with the alumite film used for the pack battery concerning an embodiment. It is an expansion | deployment perspective view of the battery pack which concerns on the conventional form.

Explanation of symbols

1 pack battery
DESCRIPTION OF SYMBOLS 10 Unit cell 11 Exterior can 11a Anodized coating 11b Exterior can body 12 Sealing plate 13 Print processing part 20 Cover body

Claims (4)

An oxidation step for anodizing the outer surface of the bottomed cylindrical outer can body made of the aluminum-containing material, including the bottom surface and from the bottom side end to the opening side end,
After the oxidation step, an outer can manufacturing step for preparing an outer can by removing the opening side edge of the outer can body, and
After the said exterior can preparation step, the sealing step which seals the opening part of the said exterior can with a sealing board is performed. The manufacturing method of the unit cell characterized by the above-mentioned. In the sealing step,
Disposing the sealing plate so as to contact the inner circumferential surface of the outer can, among the contact portions between the outer can and the sealing plate, to claim 1, characterized in that welding the portion facing the external space The manufacturing method of the unit cell of description. The method for manufacturing a unit cell according to claim 2 , wherein after the oxidation step, a predetermined pattern or character is applied by etching or printing to the outer can portion subjected to the anodizing treatment. A unit cell manufacturing step of manufacturing a unit cell by the unit cell manufacturing method according to any one of claims 1 to 3 , and a cover body is disposed so as to cover a top surface of the unit cell on which the sealing plate is disposed. A cover body disposing step to be installed,
In the cover body arranging step,
A protective circuit board that electrically protects the unit cell from overcharge or overdischarge is screwed to the sealing plate so as to be electrically connected to each of the positive electrode terminal and the negative electrode terminal of the unit cell. Joined,
Each of the positive electrode terminal and the negative electrode terminal is connected to the protection circuit board by the tightening force of the screw joint. A method of manufacturing a battery pack, comprising:

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