JP2020173989A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

To provide a non-aqueous electrolyte secondary battery having high reliability which can suppress expansion of an exterior body and leakage of non-aqueous electrolyte even in use under a vacuum environment.SOLUTION: A non-aqueous electrolyte secondary battery includes an electrode group which has a positive electrode plate, a negative electrode plate and a separator and has first and second side surfaces, a non-aqueous electrolyte, a positive electrode current collecting lead extending from the first side surface, a negative electrode current collecting lead extending from the second side surface, an exterior packaging body which is configured by a laminate having a stainless foil and a thermal fusion resin layer, a positive electrode terminal and a negative electrode terminal. A sealant portion is formed so as to cover the peripheral surface of each terminal portion passing through the sealing portion, and is heat-sealed with the thermal fusion resin layer. The thickness of the thermal fusion resin layer is not less than 30 μm and not more and 80 μm, and when the widths of a first side and a second side are represented by W1 and the widths of the positive electrode terminal and the negative electrode terminal are represented by W2, the ratio of W2/W1 is not less than 0.32 and not more than 0.48. The non-aqueous electrolyte secondary battery is used under an external pressure of not less than 0.1 Pa and not more than 100 Pa.SELECTED DRAWING: Figure 1

Description

The present invention relates to a non-aqueous electrolyte secondary battery.

In recent years, non-aqueous electrolyte secondary batteries, for example, lithium ion secondary batteries, have become widespread because of their high energy density, and are installed as power sources for small portable devices such as mobile phones, digital cameras, and laptop computers. ing. In addition, due to consideration for environmental issues, the demand for rechargeable non-aqueous electrolyte secondary batteries is increasing. Currently, non-aqueous electrolyte secondary batteries are being developed as storage batteries for electric vehicles, residential or business facilities, and as storage batteries for artificial satellites or planetary explorers for space development.

A cylindrical can, a square can, or a laminated film is generally used for the exterior body of the non-aqueous electrolyte secondary battery. The battery whose outer body is a laminated film has advantages that it is lighter in weight, has higher heat dissipation, and can have a higher volume energy density than the battery whose outer body is a cylindrical can or a square can, and is widely used. are doing. Patent Document 1 discloses a non-aqueous electrolyte secondary battery including an exterior body formed of a laminated film having a metal layer made of aluminum or an aluminum alloy.

In such a non-aqueous electrolyte secondary battery, a group of rectangular parallelepiped electrode plates is housed in an exterior body made of a laminated film. The laminated film constituting the exterior body includes a metal layer and a heat-sealing resin layer. In the exterior body, the peripheral edges of the heat-sealed resin layer are heat-sealed to form a sealing portion, and the electrode group is sealed. The electrode group has a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and holds a non-aqueous electrolyte. A band-shaped positive electrode current collecting lead and a negative electrode current collecting lead are electrically connected to the positive electrode plate and the negative electrode plate, respectively. The positive electrode current collecting lead and the negative electrode current collecting lead are electrically connected to the positive electrode terminal and the negative electrode terminal, respectively, inside the exterior. The positive electrode terminal and the negative electrode terminal each pass through the sealing portion of the exterior body and extend to the outside.

Japanese Unexamined Patent Publication No. 2004-241381

In a conventional non-aqueous electrolyte secondary battery in which the exterior body is a laminated film, when used in a vacuum environment (in an environment where the external pressure is 0.1 Pa or more and 100 Pa or less), the exterior body expands or the sealing portion is cleaved. There was a problem that water electrolyte leaked. The expansion of the exterior body is mainly due to the gas generated from the electrode group at high temperature. In a vacuum environment, the gas generated by the difference between the internal pressure and the external pressure expands, so that the exterior body tends to expand. The expansion of the outer body causes pressure or deformation on the electrode group housed in the outer body, which causes an increase in internal resistance and an internal short circuit due to damage to the electrode group. Further, the expansion of the exterior body lowers the adhesion strength between the heat-sealed resin layers of the sealing portion, and causes leakage of the non-aqueous electrolyte due to the cleavage of the sealing portion.
The present invention solves the above problems and provides a highly reliable non-aqueous electrolyte secondary battery capable of suppressing expansion of an exterior body and leakage of non-aqueous electrolyte even when used in a vacuum environment. ..

In order to solve the above problems, the non-aqueous electrolyte secondary battery according to one embodiment has a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and faces each other. A rectangular body-shaped electrode group having a first side surface and a second side surface; a non-aqueous electrolyte held by the electrode group; a band-shaped positive electrode current collection electrically connected to a positive electrode plate and extending from the first side surface. Leads; Strip-shaped negative electrode current collecting leads that are electrically connected to the negative electrode plate and extend from the second side surface; one or two sheets provided with a stainless steel foil and a heat-sealing resin layer coated on one side of the stainless steel foil. The heat-sealed resin layers of the laminated film are arranged so as to face each other, the electrode group is housed between the heat-sealed resin layers, and the peripheral edges of the heat-sealed resin layers are heat-sealed. An exterior body that seals the electrode group by forming a sealing portion; one end is electrically connected to the positive electrode current collecting lead, and the other end passes through the sealing portion and extends to the outside. And one end is electrically connected to the negative electrode current collecting lead, and the other end is provided with a negative electrode terminal that passes through a sealing portion and extends to the outside. The sealant portion is formed so as to cover the peripheral surfaces of the positive electrode terminal and the negative electrode terminal portion that pass through the sealing portion, respectively, and is heat-sealed with the heat-sealing resin layer. The thickness of the heat-sealed resin layer is 30 μm or more and 80 μm or less. Assuming that the widths of the first side surface and the second side surface are W1 and the widths of the positive electrode terminal and the negative electrode terminal are W2, the ratio of W2 / W1 is 0.32 or more and 0.48 or less, respectively. The non-aqueous electrolyte secondary battery is used in an environment where the external pressure is 0.1 Pa or more and 100 Pa or less.

According to the present invention, it is possible to provide a highly reliable non-aqueous electrolyte secondary battery capable of suppressing expansion of the exterior body and leakage of the non-aqueous electrolyte even when used in a vacuum environment.

It is a top view which shows the electrode group provided in the non-aqueous electrolyte secondary battery which concerns on 1st Embodiment. It is an exploded perspective view which shows the electrode group provided in the non-aqueous electrolyte secondary battery which concerns on 1st Embodiment. It is a perspective view which shows the non-aqueous electrolyte secondary battery which concerns on 1st Embodiment. It is sectional drawing which follows the IV-IV line of FIG. It is an exploded perspective view which shows the non-aqueous electrolyte secondary battery which concerns on 2nd Embodiment. The spacers are shown, (a) is a perspective view seen from the first surface side, (b) is a perspective view seen from the second surface side, and (c) is a sectional view taken along the line CC of (a). Is. It is sectional drawing of a part of the battery of FIG. It is sectional drawing which shows the other form of a spacer.

Hereinafter, some embodiments will be described with reference to the drawings.
The drawings may be schematically shown as compared with actual embodiments in order to clarify the description, but the drawings are merely examples and do not limit the interpretation of the present invention. In each figure, the reference numerals may be omitted for the same or similar elements arranged consecutively. Further, in the present specification and each figure, components exhibiting the same or similar functions as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and duplicate detailed description may be omitted.

[First Embodiment]
Hereinafter, the non-aqueous electrolyte secondary battery according to the first embodiment will be described in detail.
The non-aqueous electrolyte secondary battery is used in an extremely low pressure environment (hereinafter, referred to as a vacuum environment) in which the external pressure is 0.1 Pa or more and 100 Pa or less. That is, the non-aqueous electrolyte secondary battery is not particularly limited as long as it is used in the environment, but is suitably applied to, for example, a storage battery for an artificial satellite or a planetary probe for space development.

(Structure of non-aqueous electrolyte secondary battery)
Hereinafter, the non-aqueous electrolyte secondary battery according to the first embodiment will be described with reference to FIGS. 1 to 4 by taking a laminated lithium ion secondary battery as an example. FIG. 1 is a plan view showing a group of electrodes included in the non-aqueous electrolyte secondary battery (laminated lithium ion secondary battery) according to the first embodiment. FIG. 2 is an exploded perspective view showing the electrode group of FIG. FIG. 3 is a perspective view showing a laminated lithium ion secondary battery. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG.

As shown in FIG. 1, the laminated lithium ion secondary battery 1 includes a rectangular parallelepiped (for example, a rectangular parallelepiped) electrode group 3. The electrode group 3 has a first side surface F1 and a second side surface F2 facing each other. The electrode group 3 has a third side surface F3 and a fourth side surface F4 which are other side surfaces facing each other. In this specification, as shown in FIG. 1, the direction parallel to the direction along the first and second side surfaces F1 and F2 of the electrode group 3 is the X direction, and the third and fourth side surfaces of the electrode group 3 The direction parallel to the direction along F3 and F4 is defined as the Y direction, and the direction perpendicular to the X direction and the Y direction is defined as the Z direction. The first and second side surfaces F1 and F2 each have a width W1 in the X direction. For example, the electrode group 3 has a length in the Y direction longer than the width W1 in the X direction.

In the electrode group 3, for example, as shown in FIG. 2, a plurality of positive electrode plates 4, negative electrode plates 5, and separators 6 interposed between them are laminated in the Z direction so that the negative electrode plate 5 is located on the outermost layer. It is configured.
As shown in FIG. 4, the positive electrode plate 4 is composed of a positive electrode current collector 42 and positive electrode layers 41 and 41 formed on both sides of the current collector 42. The positive electrode current collector 42 is a rectangular metal foil, and is formed of, for example, an aluminum foil. The positive electrode current collector 42 has a thickness of, for example, 5 μm to 100 μm. The positive electrode layers 41 and 41 include a positive electrode active material capable of occluding and releasing lithium ions, and include, for example, a positive electrode active material, a conductive agent, and a binder. As the positive electrode active material, for example, a lithium-containing metal oxide such as LiCoO ₂ , lithium metal phosphate, or the like can be used alone or in combination. As the conductive material, for example, conductive carbon such as carbon black can be used alone or in combination. As the binder, for example, a polymer material such as polyvinylidene fluoride or styrene-butadiene rubber can be used alone or in combination.

As shown in FIG. 4, the negative electrode plate 5 located in the outermost layer is composed of a negative electrode current collector 52 and a negative electrode layer 51 formed on a surface of the current collector 52 facing the separator 6. The negative electrode plate 5 located between the positive electrode plates 4 excluding the negative electrode plate 5 located in the outermost layer is composed of a negative electrode current collector 52 and negative electrode layers 51 and 51 formed on both sides of the current collector 52. ing. The negative electrode current collector 52 is a rectangular metal foil, and is formed of, for example, a copper foil, a nickel foil, or the like. The negative electrode current collector 52 has a thickness of, for example, 5 μm to 100 μm. The negative electrode layer 51 contains a negative electrode active material capable of occluding and releasing lithium ions, and contains, for example, a negative electrode active material, a conductive agent, and a binder. As the negative electrode active material, for example, carbons such as artificial graphite and natural graphite can be used alone or in combination. As the conductive material and the binder, for example, the same ones used for the positive electrode plate can be used.

On the electrode group 3, for example, as shown in FIG. 1, two tapes 10 are attached to the back surface of the electrode group 3 so as to straddle the third side surface F3 from the front surface of the electrode group 3. Further, for example, two tapes 10 are attached to the electrode group 3 from the front surface of the electrode group 3 to the back surface across the fourth side surface F4. These tapes 10 prevent the laminated positive electrode plate 4 and the negative electrode plate 5 from being displaced.

A non-aqueous electrolyte is retained in the electrode group 3. The non-aqueous electrolyte is, for example, a non-aqueous solvent and a non-aqueous electrolyte solution containing an electrolyte. As the non-aqueous solvent, for example, aprotic organic solvents such as ethylene carbonate, propylene carbonate and dimethyl carbonate can be used alone or in combination. As the electrolyte, for example, lithium salts such as LiPF ₄ and LiBF ₄ can be used alone or in combination.

The separator 6 is formed of a microporous film that allows the electrolyte to permeate, for example, a microporous polyolefin film having a thickness of 50 μm to 200 μm.

A band-shaped positive electrode current collecting lead 43 is electrically connected to the side surface of the positive electrode plate 4 located on the first side surface F1 side of the electrode group 3. As shown in FIG. 1, the positive electrode current collector lead 43 extends in the Y direction from the central position of the positive electrode current collector 42 in the X direction. The positive electrode current collector lead 43 is integrally molded with, for example, the positive electrode current collector 42. As shown in FIG. 1, the positive electrode current collecting lead 43 has a width W3 in the X direction. The positive electrode current collecting lead 43 has a thickness of, for example, 5 μm to 100 μm.

A band-shaped negative electrode current collecting lead 53 is electrically connected to the side surface of the negative electrode plate 5 located on the second side surface F2 side of the electrode group 3. As shown in FIG. 1, the negative electrode current collector lead 53 extends in the Y direction from the central position of the negative electrode current collector 52 in the X direction. The negative electrode current collector lead 53 is integrally molded with, for example, the negative electrode current collector 52. As shown in FIG. 1, the negative electrode current collecting lead 53 has a width W3 in the X direction. The negative electrode current collector lead 53 has a thickness of, for example, 5 μm to 100 μm.

As shown in FIG. 4, a plurality of negative electrode current collecting leads 53 extending from the side surface of each negative electrode plate 5 located on the second side surface F2 side of the electrode group 3 are arranged in the stacking direction (Z direction) of the electrode group 3. Along, for example, they are focused downward, bent in the Y direction, cut so that the end faces are aligned, and joined to each other. Although not shown, a plurality of positive electrode current collecting leads 43 extending from the side surfaces of the positive electrode plates 4 located on the first side surface F1 side of the electrode group 3 are also focused, bent, and cut in the same manner as the negative electrode current collecting leads 53. It is joined.

The tip of the focused positive electrode current collecting lead 43 is, for example, bonded to one end side (for example, the upper surface in FIG. 4) of the positive electrode terminal 7 by ultrasonic welding, resistance welding, or the like, and is electrically connected. The other end of the positive electrode terminal 7 passes through the sealing portion 25 of the exterior body 2 described later and extends to the outside. The positive electrode terminal 7 is a metal plate, and is formed of, for example, a rectangular aluminum plate, a stainless steel plate, or the like. The positive electrode terminal 7 has a thickness of, for example, 100 μm to 500 μm, and has a width W2 along the X direction as shown in FIG. The positive electrode terminal 7 may be nickel-plated, for example, in a portion extending to the outside thereof. The cross-sectional area of the positive electrode terminal 7 cut along the X direction is preferably 8 mm ² or more and 15 mm ² or less. By setting the cross-sectional area of the positive electrode terminal 7 to the above range, good charge / discharge characteristics can be obtained even if the battery 1 is charged / discharged at a high rate.

The tip of the focused negative electrode current collecting lead 53 is bonded to, for example, one end side (for example, the upper surface in FIG. 2) of the negative electrode terminal 8 by ultrasonic welding, resistance welding, or the like, and is electrically connected. The other end of the negative electrode terminal 8 passes through the sealing portion 25 of the exterior body 2 described later and extends to the outside. The negative electrode terminal 8 is a metal plate, and is formed of, for example, a rectangular copper plate, a nickel plate, or the like. The negative electrode terminal 8 has a thickness of, for example, 100 μm to 500 μm, and has a width W2 along the X direction as shown in FIG. The negative electrode terminal 8 may be nickel-plated, for example, in a portion extending to the outside thereof. The cross-sectional area of the negative electrode terminal 8 cut along the X direction is preferably 8 mm ² or more and 15 mm ² or less for the same reason as that of the positive electrode terminal 7.

As shown in FIG. 1, assuming that the widths of the first side surface F1 and the second side surface F2 are W1 and the widths of the terminals 7 and 8 are W2, the ratio of W2 / W1 is 0.32 or more and 0.48 or less, respectively. Is. By defining the W2 / W1 ratio to 0.32 or more and 0.48 or less, the reaction heat generated in the electrode group 3 during charging and discharging is exposed to the outside through the current collecting leads 43 and 53, respectively. It can be transmitted to 8 and heat can be dissipated efficiently. Therefore, it is possible to suppress the generation of gas from the electrode group 3 at a high temperature, suppress the expansion of the exterior body 2, and improve the reliability of the battery 1. Further, by defining the ratio of W2 / W1 to 0.32 or more and 0.48 or less, good charge / discharge characteristics can be obtained even if the battery 1 is charged / discharged at a high rate.

If the ratio of W2 / W1 is less than 0.32, efficient heat dissipation may not be possible and good discharge characteristics at a high rate may not be obtained. On the other hand, if the W2 / W1 ratio exceeds 0.48, the weight energy density of the battery 1 may decrease as the weight of each of the terminals 7 and 8 increases.

Here, it is preferable that the width W3 of each of the current collecting leads 43 and 53 and the width W2 of each of the terminals 7 and 8 are about the same. Specifically, the ratio of W2 / W3 is preferably 0.8 or more and 1.2 or less, respectively. By setting the ratio of W2 / W3 to this range, the width of each current collecting lead can be made appropriate, so that the heat dissipation of the battery 1 can be further improved, and even if the battery 1 is charged and discharged at a high rate, it is further improved. Good charge / discharge characteristics can be obtained. Further, it is possible to suppress a decrease in the weight energy density of the battery 1 as the weight of each of the current collecting leads 43 and 53 increases unnecessarily.

As shown in FIGS. 1 and 4, the sealant portion 9 is formed so as to cover the peripheral surfaces of the positive electrode terminal 7 and the negative electrode terminal 8 that pass through the sealing portion 25 of the exterior body 2 described later, respectively. The sealant portion 9 is heat-sealed with the heat-sealing resin layers 21a and 24a of the laminated films 21 and 24 described later to improve the adhesion strength of the sealing portion 25 through which the terminals 7 and 8 pass. The sealant portion 9 is formed of a thermoplastic resin, for example, polypropylene, polyethylene, or the like. The sealant portion 9 preferably has a thickness of 100 μm or more and 200 μm or less, and more preferably 100 μm or more and 150 μm or less.

The laminated lithium ion secondary battery 1 includes an exterior body 2 composed of one or two laminated films for accommodating the electrode group 3 described above. As shown in FIG. 3, the exterior body 2 is composed of, for example, two laminated films 21 and 24. On the other hand, the laminated film 21 has a bottomed rectangular hollow accommodating recess 22 and a frame-shaped flange portion 23 located on the peripheral edge of the accommodating recess 22. The other laminated film 24 has an outer diameter dimension equal to that of the laminated film 21 and is flat. The laminated films 21 and 24 have a rectangular outer shape, for example.

The laminated films 21 and 24 are provided with stainless steel foils 21b and 24b and heat-sealing resin layers 21a and 24a coated on one side of the stainless steel foils 21b and 24b, respectively, and specifically, as shown in FIG. 4, respectively. The resin-bonded layers 21a and 24a, the metal layers 21b and 24b made of stainless steel foil, and the protective layers 21c and 24c are laminated in this order from the inside to the outside. The laminated films 21 and 24 are arranged so that the heat-sealed resin layers 21a and 24a face each other, and the electrode group 3 is housed between the heat-sealed resin layers 21a and 24a. The exterior body 2 has a sealing portion 25 formed by heat-sealing the peripheral portions (flange portions 23) of the heat-sealing resin layers 21a and 24a of the two laminated films 21 and 24. The electrode group 3 is shielded from the outside air by the exterior body 2 and sealed.

The heat-sealed resin layers 21a and 24a are made of, for example, polypropylene, polyethylene, or the like. The heat-sealed resin layers 21a and 24a have a thickness of 30 μm or more and 80 μm or less. By setting the thickness of the heat-sealed resin layers 21a and 24a within this range, the adhesion strength of the sealing portion 25 is improved, and leakage of the non-aqueous electrolyte due to the cleavage of the sealing portion 25 in a vacuum environment is suppressed. Can be done. If the thickness of the heat-sealed resin layers 21a and 24a is less than 30 μm, the adhesion strength of the sealing portion 25 may be insufficient. If the thickness of the heat-sealed resin layers 21a and 24a is less than 30 μm, the heat-sealed resin layers melt and flow when the sealing portion 25 is formed, and the stainless foils 21b and 24b and the terminals 7 and 7 There is a risk of contact with 8 and an internal short circuit. On the other hand, if the thickness of the heat-sealed resin layers 21a and 24a exceeds 80 μm, heat transfer to each heat-sealed resin layer is insufficient when the sealing portion 25 is formed, and the adhesion strength of the sealing portion 25 is insufficient. May run short. The preferred thickness of the heat-sealed resin layers 21a and 24a is 30 μm or more and 50 μm or less.

The metal layers 21b and 24b made of stainless steel foil give the exterior body 2 rigidity that can withstand use in a vacuum environment, preferably have a thickness of 50 μm or more and 200 μm or less, and have a thickness of 100 μm or more and 200 μm or less. Is more preferable. If the thickness of the stainless steel foil is less than 50 μm, the exterior body 2 may not be provided with rigidity capable of suppressing expansion in a vacuum environment. On the other hand, if the thickness of the stainless steel foil exceeds 500 μm, the weight energy density of the battery 1 may decrease as the weight of the exterior body 2 increases, and molding by press working or the like may become difficult. is there.

The protective layers 21c and 24c protect the metal layers 21b and 24b made of stainless steel foil, and are formed of, for example, nylon, polyethylene terephthalalate (PET), or the like. The protective layers 21c and 24c have a thickness of, for example, 5 μm or more and 50 μm or less.

As shown in FIG. 3, the sealing portion 25 has a rectangular frame shape having an average width W4. The width W4 of the sealing portion 25 preferably has a width of 10 mm or more and 20 mm or less, and more preferably 10 mm or more and 15 mm or less. If the width W4 is less than 10 mm, the adhesion strength of the sealing portion 25 may be insufficient. If the width W4 exceeds 20 mm, the weight energy density of the battery 1 may decrease as the weight of the exterior body 2 increases.

According to such a configuration, since the exterior body 2 is provided with highly rigid stainless steel foils 21b and 24b, expansion of the exterior body 2 can be suppressed even when the battery 1 is used in a vacuum environment. .. Further, by setting the W2 / W1 ratio to 0.32 or more and 0.48 or less, the heat dissipation of the battery 1 can be improved and the generation of gas from the electrode group 3 can be suppressed, so that the exterior body 2 can be expanded. It can be further suppressed. Further, the heat-sealed resin layers 21a and 24a have a specific thickness, and the sealant portion 9 covers the peripheral surfaces of the positive electrode terminal 7 and the negative electrode terminal 8 that pass through the sealing portion 25 of the exterior body 2, respectively. Since it is formed, the adhesion strength of the sealing portion 25 can be improved. Therefore, even if the battery 1 is used in a vacuum environment, the cleavage of the sealing portion 25 of the exterior body 2 can be suppressed, and the leakage of the non-aqueous electrolyte can be suppressed. As a result, it is possible to realize a highly reliable non-aqueous electrolyte secondary battery 1 in which expansion of the exterior body 2 and leakage of the non-aqueous electrolyte solution are suppressed. Further, by setting the W2 / W1 ratio to 0.32 or more and 0.48 or less, the battery 1 can obtain good charge / discharge characteristics even if the battery 1 is charged / discharged at a high rate.

In addition to the above-described configuration, various embodiments described below can be adopted as the first embodiment.
An insulating film may be further formed between the terminals 7 and 8 and the sealant portion 9 at the portion where the sealant portion 9 of the terminals 7 and 8 is formed. The insulating coating has a thickness of, for example, 10 μm or more and 50 μm or less, and is made of polypropylene, polyethylene, or the like. By forming the insulating film, when the sealing portion is formed, the flow due to melting of the sealant portion 9 and the heat-sealed resin layers 21a and 24a is prevented, and the stainless foils 21b and 24b are brought into contact with the terminals 7 and 8 respectively. Internal short circuit can be further suppressed.

The exterior body is not composed of two laminated films, but may be formed by bending one laminated film. Further, the laminated film of the exterior body is not limited to one in which one of the two laminated films has a housing recess and the other is flat, and both of the two laminated films may have a storage recess.

The non-aqueous electrolyte secondary battery is not limited to the laminated lithium ion secondary battery, and may be various batteries including an exterior body made of a laminated film. For example, the non-aqueous electrolyte secondary battery may be a wound lithium ion secondary battery in which the wound electrode group is crushed into a flat rectangular body.

(Manufacturing method of non-aqueous electrolyte secondary battery)
Hereinafter, the method for manufacturing the non-aqueous electrolyte secondary battery according to the first embodiment will be described by taking a laminated lithium ion secondary battery as an example.
A positive electrode slurry is prepared by mixing a positive electrode active material, a conductive agent, a binder, and a solvent. Next, this positive electrode slurry is applied to both sides of the positive electrode current collector. Then, after the solvent is dried and compressed, the strip-shaped positive electrode current collector lead 43 is cut so as to extend from one side of the positive electrode plate 4 which is the rectangular positive electrode current collector 42 on which the positive electrode layer 41 is formed. ..

A slurry is prepared by mixing a negative electrode active material, a binder, and a solvent. Next, this negative electrode slurry is applied to both sides of the negative electrode current collector. Then, after the solvent is dried and compressed, the strip-shaped negative electrode current collector lead 53 is cut so as to extend from one side of the negative electrode plate 5 which is the rectangular negative electrode current collector 52 on which the negative electrode layer 51 is formed. ..

Next, the positive electrode plate 4 and the negative electrode plate 5 are alternately laminated via the separator 6 to prepare the electrode group 3. The negative electrode plates 5 are located on both end faces of the electrode group 3 in the stacking direction (Z direction). At this time, the positive electrode current collecting lead 43 and the negative electrode current collecting lead 53 are laminated so as to extend in the Y direction from the first and second side surfaces F1 and F2 of the electrode group 3, respectively. In order to prevent the positive electrode plate 4 and the negative electrode plate 5 from being displaced, the tape 10 is attached to the upper surface, each side surface, and the lower surface on the third and fourth side surfaces F3 and F4 of the electrode group 3.

Next, the current collecting leads 43 and 53 extending from the electrode group 3 are focused on one side along the stacking direction (Z direction) of the electrode group 3, respectively, and are focused in the direction perpendicular to the Z direction (Y direction). ), And cut the tip so that the end faces are aligned. The ends of the focused current collector leads 43 and 53 are superposed on the upper surfaces of the terminals 7 and 8 and joined to each other by ultrasonic welding. Next, a sealant portion 9 covering the peripheral surface is formed in each of the portions of the terminals 7 and 8 that pass through the sealing portion 25.

After that, the heat-sealed resin layers 21a and 24a of the two laminated films 21 and 24 are arranged so as to face each other. Next, the two laminated films 21 and 24 were overlapped between the heat-sealed resin layers 21a and 24a so that the electrode group 3 was housed in the accommodating recess 22 of the laminated film 21. At this time, in the two laminated films 21 and 24, the portion where the sealant portion 9 of each terminal 7 and 8 is formed passes between the peripheral portions thereof, and a part of each terminal 7 and 8 is exposed to the outside. Arrange as follows. In this state, the peripheral edges of the heat-sealing resin layers 21a and 24a are heat-sealed with a heat-sealing machine on three sides including the side on which the terminals 7 and 8 of the laminated films 21 and 24 extend. At this time, the heat-sealing resin layers 21a and 24a and the sealant portion 9 are also heat-sealed.

Next, in a reduced pressure environment, the non-aqueous electrolytic solution is injected into the electrode group 3 from one side of the laminated films 21 and 24 that is not heat-sealed. Next, in a reduced pressure environment, the remaining one side of the exterior body 2 is heat-sealed to manufacture a laminated lithium ion secondary battery 1.
In the lithium ion secondary battery, which is an example of the non-aqueous electrolyte secondary battery 1, a degassing step is performed in which the lithium ion secondary battery is preliminarily charged and discharged before being actually used as a battery, and the gas generated there is discharged. Is preferable. When the degassing step is performed, it is possible to further suppress the expansion of the exterior body 2 due to the generation of gas when the battery 1 is used.

[Second Embodiment]
Hereinafter, the non-aqueous electrolyte secondary battery according to the second embodiment will be described with reference to FIGS. 5 to 7 by taking a laminated lithium ion secondary battery as an example. The laminated lithium ion secondary battery according to the second embodiment is the same as that of the first embodiment except that a spacer is further provided. FIG. 5 is an exploded perspective view of the non-aqueous electrolyte secondary battery (laminated lithium ion secondary battery) according to the second embodiment. 6A and 6B are views showing the spacer of FIG. 5, in which FIG. 6A is a perspective view seen from the first surface side, FIG. 6B is a perspective view seen from the second surface side, and FIG. 6C is C in FIG. It is sectional drawing along the-C line. FIG. 7 is a cross-sectional view of a part of the battery shown in FIG.

As shown in FIG. 5, the laminated lithium ion secondary battery 1 includes a spacer SP that is arranged between the outer peripheral surface of the electrode group 3 and the inner surface of the accommodating recess 22 of the laminated film 21. There is. The laminated films 21 and 24 correspond to the first and second laminated films, respectively.
As shown in FIGS. 6A to 6C, the spacer SP has a rectangular frame shape, and has an inner peripheral side surface 11 facing the outer peripheral surface of the electrode group 3 and an inner surface surface of the accommodating recess 22 of the laminated film 21. It has an outer peripheral side surface 12 facing the same. The spacer SP has a first surface 13 facing the inner bottom surface of the accommodating recess 22 of the laminated film 21, and a second surface 14 opposite to the first surface 13 and facing the laminated film 24. ing. The inner peripheral side surface 11 of the spacer SP has a shape along the outer peripheral surface of the electrode group 3, and is in contact with, for example, the outer peripheral surface of the electrode group 3. The outer peripheral side surface 12 and the first surface 13 of the spacer SP have a shape along the inner side surface of the accommodating recess 22 of the laminated film 21, and are in contact with, for example, the inner side surface. The second surface 14 of the spacer SP is, for example, in contact with the inner surface of the laminated film 24 with a portion other than the notch portion 16 described later. The spacer SP is electrically insulating and is formed of, for example, a resin made of polypropylene.

As shown in FIGS. 6A to 6C, the spacer SP has an R shape at a corner portion of the laminated film 21 facing the corner portion of the accommodating recess 22. Specifically, as shown in FIG. 6A, since the spacer SP has a rectangular frame shape, the corner portion 12a of the outer peripheral side surface 12 and the angle at which the first surface 13 of the spacer SP and the outer peripheral side surface 12 intersect. The portion 15 faces the corner portion of the accommodating recess 22 having a bottomed rectangular hollow shape and has an R shape.

Further, as shown in FIG. 7, the terminals 7 and 8 pass between the laminate film 24 and the spacer SP. The spacer SP has a notch 16 at a portion through which the terminals 7 and 8 of the second surface 14 pass. The notch 16 has two notch walls 16a facing the terminals 7 and 8. The spacer SP has an R shape at a corner portion 16b where the cutout wall 16a and the inner peripheral side surface 11 intersect. Specifically, as shown in FIG. 7, the bent portions of the positive electrode current collecting lead 43 and the negative electrode current collecting lead 53 correspond to the corner portion 16b where the cutout wall 16a and the inner peripheral side surface 11 intersect. The corners 16b are in contact with each other and form an R shape along the bent shape. The thickness T1 of the spacer SP shown in FIG. 6C corresponds to, for example, the thickness of the electrode group 3. The depth T2 of the notch 16 shown in FIG. 6C is, for example, the total thickness of the bundles of the positive electrode terminal 7 and the positive electrode current collecting lead 43, or the thickness of the bundle of the negative electrode terminal 8 and the negative electrode current collecting lead 53. Corresponds to the total of.

According to such a configuration, since the shape of the exterior body 2 is supported from the inner surface by the spacer SP, it is possible to suppress the occurrence of defects such as distortion, wrinkles, and dents of the exterior body 2. Defects such as distortion of the exterior body 2 cause leakage of the non-aqueous electrolyte solution and internal short circuit due to pressure or damage to the electrode group 3 housed in the exterior body 2. Further, according to such a configuration, since the spacer SP has an R shape at each corner portion 12a, 15, 16b, the corner portion 12a, 15, 16b is a heat-sealing resin on the inner surface of the exterior body 2. It is possible to suppress damage to the layer 21a and the current collecting leads 43 and 53. Further, according to such a configuration, since the outer peripheral surface of the electrode group 3 is supported by the spacer SP, the electrode group 3 can be protected from deformation or breakage due to an external impact or pressure, and the electrode group 3 is configured. The displacement of the positive electrode plate 4 and the negative electrode plate 5 can be suppressed. As a result, it is possible to realize a non-aqueous electrolyte secondary battery having higher reliability in which leakage of the non-aqueous electrolyte and internal short circuit are prevented.

In addition to the above-described configuration, the spacer SP of the second embodiment can adopt various forms described below.
The spacer SP may open a plurality of electrolytic solution supply ports penetrating from the outer peripheral side surface 12 toward the inner peripheral side surface 11. When the metal layers 21b and 24b of the exterior body 2 are made of highly rigid stainless steel foil, the exterior body 2 and the spacer SP are in close contact with each other in the process of injecting the non-aqueous electrolytic solution, and a gap through which the non-aqueous electrolytic solution passes is unlikely to occur. .. When the spacer SP has an electrolytic solution injection port, the non-aqueous electrolytic solution injection step can be smoothly performed. The electrolytic solution supply port can also function as a path for discharging the gas generated from the electrode group 3 to the outside in the above-mentioned degassing step. Therefore, when the spacer SP has an electrolytic solution injection port, the degassing step can be smoothly performed, and the expansion of the exterior body 2 can be further suppressed. The electrolytic solution supply port may be formed on, for example, two sides other than the two sides on which the notch 16 of the spacer SP is formed.

The spacer SP is not limited to a single member, but may be a combination of a plurality of members to form a rectangular frame. When the spacer SP is composed of a single member, it is preferable because positioning of the battery 1 at the time of assembly becomes easier as compared with the case where the spacer SP is composed of a plurality of members.

8 (a) to 8 (d) are cross-sectional views showing another form of the spacer SP. 8 (a) to 8 (d) are cross-sectional views of the spacer SP at positions corresponding to FIG. 6 (c). As shown in FIG. 8A, the spacer SP further forms an R shape on the corner portion 17 where the surface facing the inner bottom surface of the laminated film 21 (that is, the first surface 13) and the inner peripheral side surface 11 intersect. Can have. This R shape is provided, for example, over the entire circumference of the corner portion 17 of the spacer SP having a rectangular frame shape. According to such a configuration, it is possible to further suppress the spacer SP from damaging the heat-sealed resin layer 21a on the inner surface of the exterior body 2.

As shown in FIG. 8B, the spacer SP is provided at a corner portion 18 where the surface of the surface facing the laminated film 24 (that is, the second surface 14) excluding the notch wall 16a and the inner peripheral side surface 11 intersect. Further, it may have an R shape. This R shape is provided, for example, over the entire circumference of the corner portion 18 of the spacer SP having a rectangular frame shape. According to such a configuration, it is possible to further suppress the spacer SP from damaging the heat-sealed resin layer 24a on the inner surface of the exterior body 2.

As shown in FIG. 8C, the spacer SP is provided at a corner portion 19 where the surface of the surface facing the laminated film 24 (that is, the second surface 14) excluding the notch wall 16a and the outer peripheral side surface 12 intersect. Can have a shape. This R shape is provided, for example, over the entire circumference of the corner portion 19 of the spacer SP having a rectangular frame shape. According to such a configuration, it is possible to further suppress the spacer SP from damaging the heat-sealed resin layer 24a on the inner surface of the exterior body 2.

As shown in FIG. 8 (d), the spacer SP may have an inclination in which the outer peripheral side surface 20 expands toward the peripheral edge side from the first surface 13 side to the second surface 14 side. At this time, the side wall of the accommodating recess 22 of the laminated film 21 of the exterior body 2 may have an inclination along the outer peripheral side surface 20 of the spacer SP. Generally, the accommodating recess 22 of the laminated film 21 is formed by a method such as press drawing or punching. When the metal layer 21b of the exterior body 2 is made of a highly rigid stainless steel foil, if the accommodating recess 22 is deeply formed, the side wall of the accommodating recess 22 may be widened to have an inclined shape. Therefore, according to such a configuration, even when the side wall of the accommodating recess 22 has the inclination, the shape of the accommodating recess 22 can be supported from the inner surface by the outer peripheral side surface 20 of the spacer SP, so that the recess of the exterior body 2 is recessed. It is possible to suppress defects such as.

The various configurations described in the first and second embodiments can be used in combination as appropriate. For example, in the exterior body of the second embodiment, both laminated films may have accommodating recesses. In that case, it is preferable to arrange the spacer SP having the above structure between the outer peripheral surface of the electrode group and each accommodating recess so that the second surfaces face each other.

(Examples and comparative examples)
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
Prototype batteries according to Examples 1 to 4 and Comparative Examples 1 and 2 were produced by the following methods. The method for manufacturing the prototype battery, which is not particularly described, is the same as the method for manufacturing the non-aqueous electrolyte secondary battery described in the first embodiment.

[Preparation of prototype battery according to Example 1]
[Preparation of positive electrode plate]
Lithium cobalt oxide (LiXCoO ₂ , 0 <X ≦ 1) 94% by weight, which is a positive electrode active material, and polyvinylidene fluoride (PVDF), which is a binder (manufactured by Kureha Co., Ltd., KF # 1120 (trade name)) ) 3% by weight, 3% by weight of a mixture of carbon black (manufactured by Imeris Graphite & Carbon Co., Ltd., super P (registered trademark)) and acetylene black, which is a conductive material, and N-methyl- as a solvent. A positive electrode slurry was prepared by dispersing in 2-pyrrolidone (NMP). Next, this positive electrode slurry was applied to both sides of an aluminum foil (thickness 15 μm) as a positive electrode current collector. Then, the solvent is dried and compressed to a thickness of 122 μm by press working, and then a region having a width of 114.5 mm and a length of 117.0 mm is a positive electrode plate which is a positive electrode current collector on which a positive electrode layer is formed. A positive electrode current collector lead having a width of 40 mm (width W3) and a length of 15.5 mm was cut so as to extend from one side.

[Manufacturing of negative electrode plate]
Artificial graphite (manufactured by Hitachi Chemical Co., Ltd., MAGD-20 (trade name)) 97.5% by weight, which is a negative electrode active material, styrene-butadiene rubber (SBR) which is a binder (manufactured by Nippon Zeon Corporation, BM400B (trade name)) )) 1.5% by weight and 1.0% by weight of carboxymethyl cellulose (CMC) (manufactured by Nippon Paper Co., Ltd., MAC350HC (trade name)) as a thickener are dispersed in water as a solvent to prepare a negative electrode slurry. did. Next, this negative electrode slurry was applied to both sides of a copper foil (thickness 8 μm) as a negative electrode current collector. Then, the solvent is dried, compressed to a thickness of 121 μm by press working, and then the region having a width of 120.5 mm and a length of 121.0 mm is a negative electrode plate which is a negative electrode current collector on which a negative electrode layer is formed. The negative electrode current collector lead having a width of 40 mm (width W3) and a length of 12.0 mm was cut so as to extend from one side.

[Preparation of electrode group]
According to the method for producing a non-aqueous electrolyte secondary battery described in the first embodiment, the 20 positive electrode plates and 21 negative electrode plates produced were alternately laminated via a separator to prepare an electrode group. The electrode group was laminated so that the positive electrode current collecting lead extends from the first side surface and the negative electrode current collecting lead extends from the second side surface. A microporous polyolefin film having a thickness of 25 μm was used as the separator. The electrode group has a rectangular parallelepiped shape, has first and second side surfaces facing each other, and has a width W1 of the first and second side surfaces of 125 mm. The electrode group was fixed with polyimide tape across the upper surface, the third or fourth side surface, and the lower surface in order to prevent the positive electrode plate and the negative electrode plate from slipping and to prevent an internal short circuit.

As the positive electrode terminal, an aluminum plate having a width W2 of 40 mm and a thickness of 0.2 mm was used. The cross-sectional area of the positive electrode terminal cut in the X direction was 8 mm ² . A part extending to the outside from the exterior body of the positive electrode terminal is nickel-plated with a thickness of 0.1 mm on the upper surface and has a thickness of 0.3 mm. As the negative electrode terminal, a copper plate having a width W2 of 40 mm and a thickness of 0.2 mm was used. The cross-sectional area of the negative electrode terminal cut in the X direction was 8 mm ² . A part extending to the outside from the exterior body of the positive electrode terminal is nickel-plated with a thickness of 0.1 mm on the upper surface and has a thickness of 0.3 mm. The ratio of W2 / W1 in the prepared electrode group was 0.32. Moreover, in the prepared electrode group, the ratio of W2 / W3 was 1. Next, the sealant portion was formed so as to cover the peripheral surfaces of the positive electrode terminal and the negative electrode terminal portion passing through the sealing portion, respectively. The sealant portion was formed of a polypropylene layer having a thickness of 100 μm.

[Exterior body]
Two laminated films as shown in FIG. 3 were prepared. One laminated film has a bottomed hollow rectangular parallelepiped housing recess and a rectangular frame-shaped collar surrounding the housing recess. The other laminated film has a rectangular flat plate shape. The laminated film consists of a heat-sealing resin layer made of polypropylene (thickness 50 μm), a metal layer made of stainless steel foil (thickness 100 μm), and a protective layer made of PET (thickness 12 μm) in this order from the inside. It has a structure laminated to the outside.

[Assembly of prototype battery]
A prototype battery was assembled using the prepared electrode group and the laminated film according to the method for manufacturing a non-aqueous electrolyte secondary battery described in the first embodiment.
The sealing portions of the two laminated films constituting the exterior body were formed by using a heat sealing machine. First, the peripheral edges of the heat-sealing resin layers were heat-sealed with a heat-sealing machine on three sides including the side where each terminal of the two laminated films extended. At this time, the heat-sealed resin layer and the sealant portion were also heat-sealed. The two sides of the sealing portion extending from each terminal were sandwiched between flat heads having a temperature of 170 ° C., and a pressure of 0.45 MPa was applied and held for 12 seconds for heat fusion. The other side of the sealing portion was sandwiched between flat heads having a temperature of 230 ° C., and a pressure of 0.45 MPa was applied and held for 12 seconds for heat fusion. Then, the battery was vacuum-dried at 70 ° C. and a vacuum degree of −99 kPa for 12 hours.

Next, 65 g of a non-aqueous electrolytic solution was injected at room temperature from one side of the exterior body that had not been heat-sealed under a dew point environment of −70 ° C. to −60 ° C. at room temperature. The non-aqueous electrolyte solution is a mixed solvent in which ethylene carbonate (EC), methyl ethyl carbonate (MEC), and dimethyl carbonate (DMC) are mixed at a volume ratio of 2: 5: 3, and LiPF as an electrolyte. _{The one in which 6} was dissolved at a ratio of 1.3 mol / L was used.

Next, the remaining one side of the sealing portion was temporarily sealed under a reduced pressure environment under the conditions of a vacuum degree of 98%, a heat fusion time of 4.5 seconds, and a cooling time of 4.0 seconds. Next, a degassing step was performed in which the temporarily sealed prototype battery was charged and discharged, the temporarily sealed was released, the generated gas was discharged, and the temporarily sealed was repeated. Next, the remaining one side of the sealing portion was sandwiched between flat heads having a temperature of 230 ° C. with a heat sealing machine, and a pressure of 0.45 MPa was applied and held for 12 seconds to finally seal the exterior body. The prototype battery according to Example 1 had a battery weight of 350 g and a theoretical capacity of 10 Ah. The average width W4 of the sealing portion of the produced prototype battery was 10 mm.

[Making a prototype battery according to Example 2]
It was produced in the same manner as the prototype battery according to Example 1 except that the width W2 of each terminal was 50 mm and the ratio of W2 / W1 was 0.40.

[Making a prototype battery according to Example 3]
Similar to the prototype battery according to Example 1, except that the width W2 of each terminal is 60 mm, the ratio of W2 / W1 is 0.48, and the thickness of the heat-sealed resin layer of each laminated film is 80 μm. Made in.

[Making a prototype battery according to Example 4]
It was produced in the same manner as the prototype battery according to Example 3 except that the thickness of the heat-sealed resin layer of each laminated film was 30 μm.

[Production of prototype battery according to Comparative Example 1]
Prototype according to Example 1 except that the width W2 of the positive electrode terminal and the negative electrode terminal is 30 mm, the ratio of W2 / W1 is 0.24, and the thickness of the heat-sealed resin layer of each laminated film is 15 μm. It was made in the same way as a battery.

[Production of prototype battery according to Comparative Example 2]
It was produced in the same manner as the prototype battery according to Comparative Example 1 except that an aluminum foil was used instead of the stainless steel foil for the metal layer of each laminated film.

<Evaluation 1: Discharge capacity test>
The discharge capacity of each of the prototype batteries of Examples 1 to 4 and Comparative Examples 1 and 2 was measured at 25 ° C. in a vacuum environment (11 Pa to 13 Pa). In addition, the discharge capacity of each of the prototype batteries of Comparative Examples 1 and 2 was measured at 25 ° C. even in an atmospheric pressure (1013 hPa) environment.

Since the theoretical capacity of each prototype battery is 10 Ah, the current of 10 A for discharging the theoretical capacity in 1 hour is 1 ItA. For each prototype battery, the discharge capacity when discharged at 0.2 ItA and the discharge capacity when discharged at 10 ItA were measured, and the discharge capacity ratio was calculated by the following equation (1). The calculation results are shown in Table 1 below.
Discharge capacity ratio [%] = (Discharge capacity at 10 ItA / Discharge capacity at 0.2 ItA) x 100 ... (1)
In Comparative Examples 1 and 2 in which the thickness of the heat-sealed resin layer was 15 μm, when the heat-sealed resin layer was placed in a vacuum environment, the exterior body expanded and could not withstand the measurement. Therefore, Table 1 shows the atmospheric pressure environment. Only the calculation results in are shown.

<Evaluation 2: Adhesion strength test of sealing part>
For each of the prototype batteries of Examples 1 to 4 and Comparative Examples 1 and 2, a sample obtained by cutting a portion through which the positive electrode terminal of the sealing portion passes into a width of 10 mm along the X direction and a length of 30 mm along the Y direction was obtained. I prepared it. Then, in accordance with JIS K6854-2, a 180 ° peel test was performed with a tensile tester (SHIMPO FGS-100VC (trade name) manufactured by Nidec-Shimpo Co., Ltd.). As a result, each sample was peeled off between the heat-sealed resin layer of the laminated film and the sealant portion. The adhesion strength was evaluated in three stages (a: 0.6 N / mm or more, b: 0.3 N / mm or more and less than 0.6 N / mm, c: less than 0.3 N / mm). The evaluation results are shown in Table 1 below.

From the results shown in Table 1, Examples 1 to 1 in which the ratio of W2 / W1 is 0.32 or more and 0.48 or less, the metal layer is a stainless foil, and the thickness of the heat-sealed resin layer is 30 μm or more and 80 μm or less. In No. 4, it can be seen that a good discharge capacity ratio of 85% to 95% can be obtained, and a good adhesion strength of the sealing portion can be obtained.

On the other hand, in Comparative Examples 1 and 2 in which the thickness of the heat-sealed resin layer is 15 μm as described above, the adhesion strength is less than 0.6 N / mm. Therefore, when placed in a vacuum environment, the exterior body It swelled and could not be used. In Comparative Examples 1 and 2 in which the ratio of W2 / W1 was 0.24, the discharge capacity ratio in the atmospheric pressure environment was 75%, and the discharge capacity at a high rate decreased.

<Evaluation 3: Overcharge test>
100 of each of the prototype batteries of Examples 1 to 4 and Comparative Examples 1 and 2 were overcharged, and the maximum temperature at the center of each prototype battery was measured to confirm the presence or absence of a battery abnormality. Each of the prototype batteries of Examples 1 to 4 and Comparative Examples 1 and 2 was subjected to an overcharge test at 25 ° C. in a vacuum environment (11 Pa to 13 Pa).
As the charging / discharging conditions, constant current charging was performed at 10 A (1 ItA) up to 4.92 V, which is 120% of the upper limit voltage of 4.1 V of each prototype battery. When the temperature of each prototype battery is overcharged to 4.92V, a thermocouple is installed in the central portion in the X and Y directions on the accommodating recess of the exterior body with the electrode group viewed in a plan view. Was measured.

The maximum temperature at the center of each prototype battery was calculated as the average value of the maximum temperatures at the time of overcharging of 100 prototype batteries. In addition, the presence or absence of battery abnormality was visually evaluated by checking whether the exterior body was expanded, the sealing portion of the exterior body was cleaved, or the non-aqueous electrolyte solution was leaked. The battery abnormality rate was calculated by the following equation (2) from the presence or absence of battery abnormality in each of the 100 prototype batteries. The calculation results are shown in Table 2 below.
Battery abnormality rate (%) = (number of prototype batteries with abnormalities / total number of prototype batteries) x 100 ... (2)

From the results shown in Table 2, in Examples 1 to 4 in which the ratio of W2 / W1 is 0.32 or more and 0.48 or less, the temperature of the central portion of the prototype battery is 40 ° C. or less and becomes high even if overcharged. In addition, no battery abnormality such as expansion or opening of the exterior body occurred. This result is because the ratio of W2 / W1 is in the range of 0.32 or more and 0.48 or less, so that the heat generated in the electrode group is appropriately released to the outside through each terminal. Further, since the exterior body is provided with stainless steel foil, the rigidity of the exterior body is improved, and the battery abnormality of the expansion of the exterior body can be suppressed.

On the other hand, in Comparative Examples 1 and 2 in which the ratio of W2 / W1 is 0.32 or more and 0.48 or less, when overcharged, the temperature of the central portion of the prototype battery becomes a high temperature of 60 ° C., and gas is generated. A battery abnormality occurred in which the exterior body expanded and the non-aqueous electrolyte oozes out.

From the results of Examples and Comparative Examples, it was shown that the non-aqueous electrolyte secondary battery according to the present embodiment can be used in a vacuum environment, has good discharge characteristics, and has high reliability.

Although some embodiments have been specifically described, these are merely examples, and the present invention is not limited to these embodiments and examples, and various aspects based on the technical idea of the present invention are used. Can be changed.

1 ... Non-aqueous electrolyte secondary battery, 2 ... Exterior body, 21,24 ... Laminated film, 22 ... Containing recess, 23 ... Flange, 25 ... Sealing part, 3 ... Electrode group, 4 ... Positive electrode plate, 41 ... Positive electrode Layer, 42 ... positive electrode current collector, 43 ... positive electrode current collector lead, 5 ... negative electrode plate, 51 ... negative electrode layer, 52 ... negative electrode current collector, 53 ... negative electrode current collector lead, 6 ... separator, 7 ... positive electrode terminal, 8 ... Negative electrode terminal, 9 ... Sealant part, 10 ... Tape, SP ... Spacer, 11 ... Inner peripheral side surface, 12 ... Outer peripheral side surface, 12a ... Corner part, 13 ... First surface, 14 ... Second surface, 15 ... Corner part, 16 ... notch, 16a ... notch wall, 16b, 17, 18, 19 ... corner

Claims (6)

A rectangular body-shaped electrode group having a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate, and having a first side surface and a second side surface facing each other;
Non-aqueous electrolyte retained in the electrode group;
A strip-shaped positive electrode current collecting lead that is electrically connected to the positive electrode plate and extends from the first side surface;
A strip-shaped negative electrode current collecting lead that is electrically connected to the negative electrode plate and extends from the second side surface;
It is composed of one or two laminated films including a stainless steel foil and a heat-sealed resin layer coated on one side of the stainless steel foil, and the heat-sealed resin layers of the laminated film are arranged so as to face each other. An exterior body in which the electrode group is housed between the heat-sealed resin layers, the peripheral edges of the heat-sealed resin layer are heat-sealed to form a sealing portion, and the electrode group is sealed.
One end is electrically connected to the positive electrode current collector lead, the other end is a positive electrode terminal that passes through the sealing portion and extends to the outside; and one end is electrically connected to the negative electrode current collector lead, and the other Negative electrode terminal whose end extends out through the sealing portion;
A non-aqueous electrolyte secondary battery equipped with
The sealant portion is formed so as to cover the peripheral surfaces of the positive electrode terminal and the negative electrode terminal portion that pass through the sealing portion, respectively, and is heat-sealed with the heat-sealing resin layer.
Assuming that the thickness of the heat-sealed resin layer is 30 μm or more and 80 μm or less, the widths of the first side surface and the second side surface are W1, and the widths of the positive electrode terminal and the negative electrode terminal are W2, W2 The ratio of / W1 is 0.32 or more and 0.48 or less, respectively.
A non-aqueous electrolyte secondary battery used in an environment where the external pressure is 0.1 Pa or more and 100 Pa or less. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the stainless foil is 50 μm or more and 200 μm or less. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the average width of the sealing portion is 10 mm or more and 20 mm or less. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 3, further comprising a rectangular frame-shaped spacer arranged between the outer peripheral surface of the electrode group and the exterior body. The two laminated films are a first laminated film and a second laminated film.
The first laminated film has a bottomed rectangular hollow-shaped accommodating recess in which the electrode group is accommodating, and a frame-shaped flange portion located at the periphery of the accommodating recess, and the second laminated film has the second laminated film. It is a flat plate having the same outer diameter as the laminated film of 1.
The spacer has an R shape at a corner portion of the first laminated film facing the corner portion of the accommodating recess.
The positive electrode terminal and the negative electrode terminal pass between the second laminated film and the spacer, and the spacer has the positive electrode terminal and the negative electrode terminal on the surface facing the second laminated film. The fourth aspect of claim 4, wherein each of the passage portions has a notch, and the notch wall facing the positive electrode terminal and the negative electrode terminal of the notch and the corner portion where the inner peripheral side surface intersects each have an R shape. Non-aqueous electrolyte secondary battery. The non-one according to any one of claims 1 to 5, wherein the positive electrode active material used for the positive electrode plate and the negative electrode active material used for the negative electrode plate are composed of a material capable of occluding and releasing lithium ions. Water electrolyte secondary battery.

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