JP2016225153A - Electrochemical cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrochemical cell that can be easily downsized without reducing electric properties.SOLUTION: An electrochemical cell 1 comprises: an electrode body in which a positive electrode member and a negative electrode member are laminated via a separator; a sheath body 5 including an inclusive region including the electrode body and a marginal region around the inclusive region; and a protection circuit board 3 that is provided on a surface at one side of the sheath body 5. The protection circuit board 3 and at least a part of the marginal region that is adjacent to the protection circuit board 3 and folded to one side are integrally fixed by an adhesive tape. The marginal region in at least a portion of a region where the protection circuit board 3 is not provided, is fixed by an adhesive tape while being folded to one side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrochemical cell.

  2. Description of the Related Art Conventionally, an electrochemical cell having an electrode body in which a positive electrode member and a negative electrode member are laminated via a separator, and an exterior body that encloses the electrode body is known. As one form of such an electrochemical cell, there is a non-aqueous electrolyte secondary battery used as a power source for various devices (Patent Document 1).

  In this battery, a laminate film sheet including a resin layer and a metal foil is provided as an exterior body, and a blank area around an inclusion area of the exterior body is heat-sealed. With this configuration, the electrode body can be sealed inside the exterior body. Further, in this battery, a circuit board that is electrically connected to the positive electrode member or the negative electrode member of the electrode body is provided in a recess formed by bending a blank area.

  However, the circuit board material is usually formed of a hard material such as a ceramic sheet. Therefore, the circuit board may damage the exterior body and the surrounding components in a state where the electrochemical cell is mounted on the electronic component, and may cause deterioration of the electrical characteristics of the electrochemical cell and the electronic component on which the electrochemical cell is mounted. Therefore, a configuration is known in which the circuit board is covered with a fixing member such as a tape so that the circuit board does not damage the exterior body or surrounding components.

JP 2000-156208 A

However, the above prior art has the following problems.
When the circuit board and the folded blank area are integrally fixed with a fixing member, the blank area which is not fixed with the fixing member in the exterior body easily opens outward (so-called springback phenomenon), and the fixing member The width dimension becomes larger than that of the region fixed at. As a result, it is difficult to reduce the size of the electrochemical cell. Moreover, when an electrochemical cell is mounted, there is a possibility that surrounding parts are damaged by the exterior body that is easily opened, and electrical characteristics of the electronic parts are deteriorated.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrochemical cell that does not cause a decrease in electrical characteristics and can be easily reduced in size, in order to solve the above problems.

In order to achieve the above object, the present invention provides:
An electrode body in which a positive electrode member and a negative electrode member are laminated via a separator;
An exterior body having an inclusion area containing the electrode body and a blank area around the inclusion area;
A circuit board provided on one surface of the exterior body;
In an electrochemical cell comprising:
The circuit board and at least a part of the blank area bent to the one side adjacent to the circuit board are integrally fixed by a first fixing member,
At least a part of the blank area in an area where the circuit board is not provided is fixed by a second fixing member in a state of being bent to the one side.

  With this configuration, since the surface of the circuit board is protected by the first fixing member, there is no possibility of damaging the exterior body and surrounding components by the circuit board. Furthermore, at least part of the blank area in the area where the circuit board is not provided is fixed by the second fixing member in a state where it is bent to one side, so that even in the area where the circuit board is not provided, Since the opening of the blank area can be suppressed, the electrochemical cell can be miniaturized. Therefore, it is possible to provide an electrochemical cell that can be easily reduced in size without deteriorating electrical characteristics.

In the present invention,
The circuit board is provided on one end side of the surface on one side,
It is preferable that the second fixing member fixes the blank area on the other end side opposite to the one end.

  With this configuration, the circuit board is provided on one end side of the exterior body, and the blank area is fixed by the second fixing member on the other end side on the opposite side. It can fix with a fixing member, As a result, it is possible to reduce an electrochemical cell more suitably. Also, by providing a circuit board on one end side of the exterior body, it becomes possible to easily realize electrical connection between the surrounding components and the circuit board, and thus it is possible to provide an electrochemical cell having excellent electrical characteristics. It becomes possible.

In the present invention,
The electrode body has a substantially rectangular parallelepiped shape, and blank regions are formed adjacent to each other on two side surfaces facing each other, and the circuit board is provided in a recess formed by the folded blank region. It is preferable that

  With this configuration, it is possible to realize a reduction in size of the electrochemical cell while securing a space in which the circuit board is provided. Further, since the circuit board is provided in the recess, the circuit board can be protected by the bent blank area. In addition, it is easy to prevent the positional deviation of the circuit board by being provided in the recess, that is, the mounting strength of the circuit board is improved.

In the present invention,
It is preferable that the ratio of the cross-sectional area on the one end side to the cross-sectional area on the other end side is 1.30 or less.

  According to such a configuration, as compared with the conventional electrochemical cell, the springback phenomenon on the other end side can be suppressed, and the electrochemical cell can be miniaturized. Moreover, compared with the past, the volume energy density of an electrochemical cell improves and the electrochemical cell excellent in the electrical property can be provided.

In the present invention,
It is preferable that the first fixing member and the second fixing member are insulating adhesive tapes.

  According to this configuration, the circuit board can be reliably protected electrically, and the size of the electrochemical cell can be easily and reliably reduced by using the adhesive tape.

In the present invention,
For the first fixing member and the second fixing member, it is preferable that any one of a polyimide tape, a PET tape, a polyethylene tape, or a PPS film tape is used.

  According to such a configuration, it is possible to easily and reliably reduce the size of the electrochemical cell.

  Moreover, in this invention, the ratio of the adhesive force of a 1st fixing member and a 2nd fixing member is 1: 2-1: 3, It is characterized by the above-mentioned.

  According to such a configuration, by increasing the adhesive force of the second fixing member more than the adhesive force of the first fixing member, it is possible to reliably reduce the size in the width direction of the electrochemical cell in the region where the springback phenomenon is remarkable. Is possible.

  As described above, according to the present invention, it is possible to provide an electrochemical cell that is easily reduced in size without causing deterioration of electrical characteristics.

It is the schematic which shows the electrochemical cell which concerns on embodiment. It is AA 'sectional drawing which shows the top part of the electrochemical cell which concerns on embodiment. It is BB 'sectional drawing which shows the bottom part of the electrochemical cell which concerns on embodiment. It is the schematic which shows the electrochemical cell which concerns on a comparative example. It is AA 'sectional drawing which shows the top part of the electrochemical cell which concerns on a comparative example. It is BB 'sectional drawing which shows the bottom part of the electrochemical cell which concerns on a comparative example.

  With reference to FIGS. 1-3, the electrochemical cell which concerns on this embodiment is demonstrated. FIG. 1 is a schematic view showing an electrochemical cell according to the present embodiment, FIG. 2 is a cross-sectional view showing a top portion of the electrochemical cell according to the present embodiment, and FIG. 3 is an electrochemical according to the present embodiment. It is sectional drawing which shows the bottom part of a cell. In the present embodiment, a lithium ion secondary battery 1 will be described as an example of an electrochemical cell. Here, the top portion refers to the side where the protective circuit board 3 is provided in the longitudinal direction of the electrochemical cell, and the bottom portion refers to the opposite side.

(1: Overall configuration of electrochemical cell)
First, the overall configuration of the electrochemical cell according to the present embodiment will be described. Here, the description will be made using the lithium ion secondary battery 1 as an electrochemical cell. In addition, the dimension, material, etc. of each member which comprises the lithium ion secondary battery 1 are mentioned later.

The lithium ion secondary battery 1 has a substantially rectangular parallelepiped electrode body formed by superposing and winding a positive electrode member and a negative electrode member produced by applying an active material to a sheet-like current collector through a separator. ing. In addition, the dimension of the lithium secondary battery 1 in this embodiment is 19 mm in width, 32 mm in length, and 6 mm in thickness.
The outer package 5 accommodates the electrolytic solution and the above-described electrode body in the inclusion region 4 formed by folding one laminate film in two, and the three sides (folding lines around the inclusion region 4) The other three sides are sealed by heat sealing. A region around the inclusion region 4 is referred to as a blank region 6. In addition, as long as the sealing property of the inclusion region 4 can be maintained, not only the whole blank region 6 is heat-sealed, but also a configuration in which only a part is heat-sealed may be used. In this embodiment, the three sides around the inclusion region 4 are heat-sealed. However, the embodiment of the present invention is not limited to this, and all four sides including the folding line are heat-sealed. Alternatively, the outer package 5 may be formed by stacking two laminate films and heat-sealing four sides.

In addition, electrode tabs 2 are connected to current collectors (not shown) of the positive electrode member and the negative electrode member that constitute the electrode body, respectively, and a heat-sealed portion (terrace) at the edge facing the folding line of the outer package 5 The electrode tab 2 is led out from the (section). In addition, this terrace part can be said to be a part of the blank area in this embodiment.
Further, in the substantially rectangular parallelepiped electrode body, a blank area 6 is formed adjacent to each of two opposite side surfaces, and these two blank areas 6 are bent to the same side. At this time, in the bent state, the gap between the blank area 6 and the electrode body is made as small as possible. A protective circuit board 3 as a circuit board is provided in a recess formed by bending the two blank areas 6. The protection circuit board 3 is electrically connected to the electrode tab 2 led out from the terrace portion.

And in this embodiment, the adhesive tape which has insulation as a 1st fixing member is wound over the two folded blank area | regions 6 so that the protection circuit board 3, the terrace part, and the electrode tab 2 may be covered. Thus, the top tape portion 7 is formed. Furthermore, an adhesive tape having insulating properties as a second fixing member is wound around the bottom portion on the side opposite to the protection circuit board 3 so as to fix the same two blank areas 6 as described above. A bottom tape portion 8 is formed.
With this configuration, it is possible to suppress a spring back phenomenon that occurs when the adhesive tape is wound around the top tape portion 7. That is, the width dimension of the exterior body 5 can be suppressed, and the size reduction of the lithium ion secondary battery 1 can be achieved.
In the present embodiment, the adhesive tape is “wrapped” in both the top tape portion 7 and the bottom tape portion 8, but the embodiment of the present invention is not limited to this. Rather than wrapping the adhesive tape so as to wrap around the outer package 5, at least a part of the folded blank area 6, the surface of the protective circuit board 3, and the surface of the electrode tab 2 are adhesive in the top tape portion 7. What is necessary is just to be integrally fixed with the tape. Moreover, in the bottom tape part 8, the folded blank area | region 6 should just be fixed with the adhesive tape, respectively. In this case, the one blank area 6 and the other blank area 6 are not integrated with each other, and may be separately fixed to the surface of the exterior body 5 with an adhesive tape.

(2: Schematic configuration of electrode body)
In this embodiment, the positive electrode member has a positive electrode active material layer and a positive electrode current collector. Furthermore, the positive electrode active material layer is made of a positive electrode active material, a conductive additive, and a binder, and is formed on both surfaces of a positive electrode current collector made of pure aluminum foil.
The negative electrode member has a negative electrode active material layer and a negative electrode current collector. Furthermore, the negative electrode active material layer is made of a negative electrode active material, a conductive additive, and a binder, and is formed on both surfaces of a negative electrode current collector made of a pure copper foil.

  In addition, a separator is interposed between the positive electrode member and the negative electrode member, and the sheet-like positive electrode member, the sheet-like negative electrode member, and the separator are integrally wound in the longitudinal direction with the separator interposed therebetween. The electrode body in this embodiment is formed. The separator has a property of allowing lithium ions to pass through, and is formed by one or a combination of two or more of a resin porous film, a glass nonwoven fabric, and a resin nonwoven fabric. In this embodiment, the separator has a thickness of 20 μm. A separator that is a microporous polyethylene film is used. According to such a configuration, when lithium ions move from one of the positive electrode member and the negative electrode member to the other, charge can be accumulated (charged) or the charge can be discharged (discharged).

  The material of the positive electrode current collector is not limited to the above material, and an aluminum alloy may be used. Furthermore, the material of the positive electrode active material may be a double oxide containing lithium and a transition metal such as lithium cobaltate, lithium titanate, and lithium manganate. The method for adjusting the positive electrode active material will be described later.

  The material of the negative electrode current collector is not limited to the above material, and a copper alloy may be used. The material of the negative electrode active material may also be silicon oxide, graphite, hard carbon, lithium titanate, LiAl, or the like. The method for adjusting the negative electrode active material will be described later.

(3: Schematic configuration of electrolyte)
As the electrolytic solution, a support salt dissolved in a non-aqueous solvent is used. In the present embodiment, LiFP ₆ as a supporting salt is 1 M / L in a non-aqueous solvent in which propylene carbonate (PC): ethylene carbonate (EC): ethyl methyl carbonate (EMC) is mixed at a volume ratio of 1: 1: 2. A dissolved electrolyte is used.

The supporting salt is not limited to the above-mentioned substances, and known substances can be used. For example, LiCH ₃ SO ₃ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ Organic acid lithium salts such as F ₅ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiN (CF ₃ SO ₃ ) ₂ , LiN (FSO ₂ ) ₂ ; LiPF ₆ , LiBF ₄ , LiB (C ₆ H _{5 4} ) Lithium salts such as inorganic acid lithium salts such as ₄ , LiCl, and LiBr can be used.

  Further, the non-aqueous solvent is not limited to the above-mentioned substances, but includes aliphatic monocarboxylic acid esters such as ethyl formate, propyl formate and ethyl butyrate, and chains such as dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. A cyclic carbonate such as a carbonate, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate (BC), and vinylene carbonate (VC) can be used.

(4: Schematic configuration of exterior body)
The exterior body 5 is formed by folding and laminating sheet-like laminate films. The laminate film has a metal layer, a heat-welded resin layer provided on the inner surface of the metal layer, and a protective layer provided on the outer surface of the metal layer. In this embodiment, as the exterior body 5, a 70 to 100 μm thick aluminum laminate film in which a nylon layer as a protective layer, an aluminum foil as a metal layer, and a polypropylene layer as a heat-sealing resin layer are sequentially laminated is used. .

  The material of the metal layer, the heat-welded resin layer, and the protective layer is not limited to the above materials, and a metal material other than aluminum may be used as the metal layer as long as it has a property of blocking moisture. . Moreover, you may use thermoplastic resins, such as polyethylene, an ionomer, and ethylene-methacrylate copolymer resin, as a heat welding resin layer. Moreover, you may use polyester resins, such as a polyethylene terephthalate, as a protective layer.

  The exterior body 5 is formed by overlapping sheets so that the heat-sealing resin layers are in contact with each other. In addition, a convex inclusion region (electrode storage portion) 4 for storing the electrode body in advance and a surrounding blank region 6 are formed in the exterior body 5 in advance.

(5: Schematic configuration of electrode tab)
The electrode tab 2 is connected to the current collector of the positive electrode member and the current collector of the negative electrode member by welding. For the electrode tab 2 connected to the positive electrode current collector, for example, pure aluminum or aluminum alloy can be used. Moreover, pure nickel and nickel alloy can be used for the electrode tab 2 connected to a negative electrode collector, for example.

  The electrode tab 2 may be provided with a tab film in advance. By disposing the tab film in a portion that is heat-sealed with the exterior body 5 in the blank area 6, the sealing performance of the exterior body 5 can be improved. The tab film is formed using a thermoplastic resin such as polyethylene, polypropylene, ionomer, and ethylene-methacrylate copolymer resin, similarly to the heat-welded resin layer of the outer package 5.

(6: Schematic configuration of adhesive tape)
In this embodiment, the adhesive tape which has insulation is used as a 1st fixing member and a 2nd fixing member. Examples of the adhesive tape used for the top tape portion 7 and the bottom tape portion 8 include a polyimide tape, a PET tape, a polyethylene tape, and a PPS film tape. By forming an adhesive layer on one side of these tapes, it functions as an adhesive tape. In addition, although a well-known adhesive can be applied as an adhesive, it is preferable to use a silicone type adhesive in view of adhesive strength and environmental characteristics.

  In the present embodiment, a polyimide tape having an adhesive strength of about 4 (N (gf) / 25 mm) and an elongation rate of 50% is used as the insulating tape used for the top tape portion 7. Further, in the bottom tape portion 8, a PPS film tape having an adhesive strength of about 8 (N (gf) / 25mm) and an elongation rate of 40% is used as the insulating tape. In addition, the PPS film tape in the bottom tape part 8 is 6 mm in width. Thereby, the dimension of 20% or more with respect to the longitudinal dimension of the lithium ion secondary battery 1 can be suppressed in the bottom tape portion 8, and the adhesive tape in the bottom tape portion 8 is prevented from being peeled off, and the spring back phenomenon in the bottom portion. Can be suitably suppressed.

  Note that the insulating tape of the bottom tape portion 8 has a higher adhesive strength than the insulating tape used for the top tape portion 7. Accordingly, it is possible to effectively suppress the spread of the bottom portion that is more easily spread by the springback phenomenon. The ratio of the adhesive strength may be 1: 1, but is preferably 1: 1.5 to 1: 5, and more preferably 1: 2 to 1: 3. The adhesive strength can be set to a desired strength by appropriately selecting the application amount or type of the adhesive. Moreover, the structure which suppresses a springback phenomenon by using the adhesive tape with the same adhesive force and making the width | variety of the bottom tape part 8 larger than the width | variety of the top tape part 7 may be sufficient.

  According to the earnest study of the inventors, by spreading the adhesive tape on the bottom tape portion 8 with an adhesive force 2 to 3 times the adhesive strength of the top tape portion 7, the spread of the bottom tape portion 8 can be more reliably suppressed. The point that can be done is known. Although the adhesive strength of the adhesive tape decreases with time, the adhesive tape is determined in the bottom tape portion 8 under the normal use environment of the lithium ion secondary battery 1 by previously determining the relationship of the adhesive strength as described above. There is no fear of peeling off, and the durability and safety of the product can be improved.

  In addition, as the insulating tape of the bottom tape portion 8, a tape having a lower elongation than the insulating tape used for the top tape portion 7 is used. Thereby, it is possible to further suppress the spread of the bottom tape portion 8 that is more easily spread than the top tape portion 7.

(7: About manufacturing method of electrochemical cell)
The adjustment conditions and procedure of the negative electrode mixture formed on the negative electrode member were as follows.
First, an aqueous solution of lithium hydroxide (LiOH. (H ₂ O) n) is added to an aqueous solution obtained by adding a powder of a cross-linked polyacrylic acid resin having a carboxyl group content of 50 to 70% to purified water as a binder. Was used to neutralize so that the pH was approximately 7.

Next, the conductive assistant was added to the previous binder and dispersed. At this time, carbon black was used as a conductive aid, and graphite as a negative electrode active material was further added and dispersed to prepare a negative electrode mixture slurry.
Next, the negative electrode mixture slurry is uniformly applied to both sides of the copper foil as a negative electrode current collector and dried, followed by compression molding with a roll press to produce a negative electrode sheet (sheet-like negative electrode member). did.

On the other hand, the adjustment conditions and procedure of the positive electrode mixture formed on the positive electrode member were as follows.
First, lithium manganese composite oxide as a positive electrode active material, graphite as a conductive material, and polyvinylidene fluoride as a binder are mixed (mass ratio 85: 5: 10) and dispersed in N-methyl-2-pyrrolidone as a solvent. A positive electrode mixture slurry was prepared.
Next, this positive electrode mixture slurry was applied to an aluminum foil, dried, and then compression molded by a roll press to produce a positive electrode sheet (sheet-like positive electrode member).

  Next, after cutting out the positive electrode sheet and the negative electrode sheet prepared by the above-described method and attaching the electrode tab 2 as the positive electrode terminal and the negative electrode terminal to each, the above-described separator is placed on the positive electrode sheet and the negative electrode sheet. The electrode body was produced by being sandwiched between and wound in the longitudinal direction a predetermined number of times.

  Next, the electrode tab 2 was taken out of the exterior body 5, and the electrode body was loaded into an aluminum laminate film that was folded and formed into a substantially bag shape. The laminate film is preliminarily formed with an electrode storage portion (including region 4) for storing an electrode body. Furthermore, sealing was performed by injecting the above-described electrolyte solution and thermally fusing the blank area 6 of the aluminum laminate film after defoaming. In the aluminum laminate film, an edge located opposite to the folded side and two edges perpendicular to the folded side are heat-sealed.

  Next, two sides perpendicular to the folded side of the heat-bonded blank area 6 were bent in the direction of the inner envelope area 4, and a bent portion was formed at the boundary between the inner envelope area 4 and the blank area 6. At this time, bending was performed at about 90 degrees. Note that the bending angle may be different between the top portion and the bottom portion. That is, in consideration of the spring back phenomenon at the bottom portion, the bending angle at the top portion may be larger than the bending angle at the bottom portion.

  Next, the protective circuit board 3 was connected to the electrode tab 2 led out from the exterior body 5 by resistance welding. Thereafter, an insulating tape was applied so as to cover the protection circuit board 3, the electrode tab 2 was bent in the direction of the inclusion region 4, and the protection circuit board 3 was placed on the terrace portion.

  Next, an insulating tape is wound around the protection circuit board 3, the terrace portion, and the electrode tab 2 to form a top tape portion 7. Thereafter, an insulating tape was applied to the folded one blank area 6 and the other blank area 6 opposite to the bent blank area 6 so as to cross the top tape portion 7.

(8: Comparison result with comparative example)
Next, a comparison result between the lithium ion secondary battery 1 according to the present embodiment and the lithium ion secondary battery 11 according to the comparative example will be described. 4 to 6 schematically show a lithium ion secondary battery 11 according to a comparative example.
FIG. 4 is a schematic diagram showing a lithium ion secondary battery 11 according to a comparative example. FIG. 5 is a cross-sectional view taken along the line AA ′ of FIG. 6 is a cross-sectional view taken along the line BB ′ of FIG.

  The production of the electrode body and the formation of the top tape portion 17 are the same as in this embodiment. The lithium ion secondary battery 11 according to the comparative example is different from the lithium ion secondary battery 1 according to the present embodiment in that the bottom tape portion 8 in the present embodiment is not formed.

  First, the lithium ion secondary battery 1 according to this embodiment and the lithium ion secondary battery 11 according to the comparative example are respectively stored for 24 hours, and the dimensions of the lithium ion secondary battery thereafter are shown in FIGS. The various dimensions of the top part and the bottom part shown in FIG. 6 were measured.

  First, the top portion maximum widths L11 and L31 are the maximum dimensions from one blank area 6 to the other blank area 6 in the state where the insulating tape is applied, as shown in FIGS. That is, the distance between the leading edge of one blank area 6 and the leading edge of the other blank area 6. Further, the top portion minimum widths L <b> 12 and L <b> 32 are intervals between the folding position of one blank area 6 and the folding position of the other blank area 6. Moreover, the top part heights H1 and H3 are the maximum heights of the electrochemical cells at the measurement points of the top part maximum widths L11 and L31.

  The bottom portion maximum widths L21 and L41 are the maximum dimensions from one blank area 6 to the other blank area 6 in the state where the insulating tape is applied, as shown in FIGS. That is, the distance between the leading edge of one blank area 6 and the leading edge of the other blank area 6. The bottom portion minimum widths L <b> 22 and L <b> 42 are intervals between the folding position of one blank area 6 and the folding position of the other blank area 6. Moreover, bottom part height H2, H4 is the maximum height of the electrochemical cell in the measurement location of bottom part maximum width L21, L41. Thereafter, the capacity of each battery was measured. Furthermore, the volume energy density was calculated.

  Table 1 shows the results of the lithium ion secondary battery 1 according to this embodiment. Table 2 shows the results of the lithium ion secondary battery 11 according to the comparative example.

  Table 1 and Table 2 show the battery dimensions, top cross-sectional area, bottom cross-sectional area, ratio of bottom cross-sectional area to top cross-sectional area (bottom cross-sectional area / top cross-sectional area), capacity, and volume energy density. showed that. The top cross-sectional area here refers to the cross-sectional area at the upper end of the inclusion region 4, and the bottom cross-sectional area refers to the cross-sectional area at the lower end of the electrochemical cell 1 (the region where the springback phenomenon is most prominent). Point to.

  As shown in Table 1 and Table 2, when the average values of the top portion maximum widths L11 and L31 are compared, only about 0.3 mm is generated, whereas the average values of the bottom portion maximum widths L21 and L41 are as follows. There is a difference of 1 mm or more.

  Further, when the average value of the ratio of the cross-sectional areas of the present embodiment and the comparative example is compared, the present embodiment is 1.28 while the comparative example is 1.34. Thus, in the present embodiment, it can be seen that by having the bottom tape portion 8, it is possible to reliably suppress the spread of the blank region 6 due to the temporal change in the bottom portion. As a result, when the average value of the volume energy density is compared, in this embodiment, the volume energy density can be improved by about 4% compared to the comparative example. Therefore, it is possible to achieve an improvement in electrical characteristics while achieving a reduction in size.

  Thus, according to the lithium ion secondary battery 1 which concerns on this embodiment, it becomes possible to implement | achieve size reduction, without reducing an electrical property. In the above comparison results, the ratio of the bottom cross-sectional area to the top cross-sectional area of the lithium ion secondary battery 1 was 1.28. However, in the present invention, if this ratio is 1.30 or less, Compared to the prior art, it has been found that it is possible to achieve miniaturization without degrading the electrical characteristics (1.3434 in the comparative example). In addition, the lithium ion secondary battery 1 can protect the R portion having a thin bottom portion by performing cup molding.

(9: Other embodiments)
In the above embodiment, a lithium ion secondary battery has been described as an example of an electrochemical cell, but the present invention can also be applied to other lithium ion secondary batteries, electric double layer capacitors, primary batteries, and the like. It is.

  Moreover, in the said embodiment, although the adhesive tape was respectively wound in the top tape part 7 and the bottom tape part 8, embodiment of this invention is not restricted to this. That is, the above-described effects can be obtained if the adhesive tape is attached to at least a part of the target area without being wound.

  In the said embodiment, although the protective circuit board 3 is provided in the one end part side of the longitudinal direction of the exterior body 5, embodiment of this invention is not restricted to this. That is, it is also possible to provide the protective circuit board 3 in a region other than the end portion of the exterior body 5 (for example, the central portion). Moreover, in the top tape part 7 and the bottom tape part 8, the adhesive tape is affixed on each of the margin areas 6, but the adhesive tape is affixed or wound around the entire area of the folded margin area 6. There may be.

1, 11 ... Lithium ion secondary battery (electrochemical cell)
2, 12 ... Electrode tab 3, 13 ... Protective circuit board 4, 14 ... Inclusion area 5, 15 ... Exterior body 6, 16 ... Blank area 7, 17 ... Top tape part 8 ... Bottom tape part 9, 19 ... Bending corner part L11, L31 ... Top part maximum width L12, L32 ... Top part minimum width H1, H3 ... Top part height L21, L41 ... Bottom part maximum width L22, L42 ... Bottom part minimum width H2, H4 ... Bottom part height

Claims (7)

An electrode body in which a positive electrode member and a negative electrode member are laminated via a separator;
An exterior body having an inclusion area containing the electrode body and a blank area around the inclusion area;
A circuit board provided on one surface of the exterior body;
In an electrochemical cell comprising:
The circuit board and at least a part of the blank area bent to the one side adjacent to the circuit board are integrally fixed by a first fixing member,
An electrochemical cell characterized in that at least a part of the blank region in a region where the circuit board is not provided is fixed by a second fixing member in a state of being bent to the one side. The circuit board is provided on one end side of the surface on the one side,
The electrochemical cell according to claim 1, wherein the second fixing member fixes the blank area on the other end side opposite to the one end.   The electrode body has a substantially rectangular parallelepiped shape, and the blank area adjacent to two side surfaces facing each other is bent to the one side, and the circuit board is a recess formed by the bent blank area. The electrochemical cell according to claim 1, wherein the electrochemical cell is provided inside.   The electrochemical cell according to claim 2 or 3, wherein a ratio of a cross-sectional area at the one end side to a cross-sectional area at the other end side is 1.30 or less.   5. The electrochemical cell according to claim 1, wherein the first fixing member and the second fixing member are insulating adhesive tapes. 6.   The polyimide film, PET tape, polyethylene tape, or PPS film tape is used for the first fixing member and the second fixing member, respectively. The electrochemical cell according to 1.   The electrochemical cell according to claim 5 or 6, wherein the ratio of the adhesive force between the first fixing member and the second fixing member is 1: 2 to 1: 3.

Images