JP2019110016A - Thin battery - Google Patents

Abstract

To suppress damage of an exterior package body and an electrode group in a case where a thin battery is bent.SOLUTION: The present invention relates to a thin battery 100 including an electrode group 110, a nonaqueous electrolyte and an exterior package body 120. The exterior package body includes: an inner region facing the electrode group in a view in a normal direction of one principal surface of the electrode group, and an outer peripheral region other than the inner region. The outer peripheral region includes a first region positioned in an outermost periphery of the exterior package body, a second region adjacent to the inside of the first region, and a third region adjacent to the inside of the second region. The first region and the second region form an encapsulation part. A thickness H1 of the thin battery in the first region and a thickness H2 of the thin battery in the second region satisfy a relationship of H1<H2, the third region includes a thin portion, a thickness H3 of the thin battery in the thin portion and the thickness H2 satisfy a relationship of H3<H2, and the thickness H1 and the thickness H3 satisfy a relationship of H1<H3.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a thin battery, and more particularly to improvement of the fixability of the thin battery.

  In recent years, as a power source for small-sized electronic devices such as biomedical devices, mobile phones, voice recording / reproducing devices, watches, moving picture and still picture shooting machines, liquid crystal displays, calculators, IC cards, temperature sensors, hearing aids and pressure sensitive buzzers. A thin battery is used. Such thin batteries are required to have flexibility. Therefore, the exterior of the thin battery is formed, for example, by heat-sealing two sheets including a resin layer (Patent Document 1).

JP 2011-204590 A

  In general, heat fusion is performed by sandwiching an outer peripheral region located on the outer peripheral side of two stacked sheets with a pair of heat seal bars. Therefore, as shown in FIG. 4, the outer peripheral region 222 of the exterior body 220 is disposed closer to the center in the thickness direction of the thin battery.

  The thin battery may be used by being fixed to a predetermined surface (fixed surface) of the electronic device by, for example, a double-sided tape or the like. As described above, when the outer peripheral area 222 of the outer package 220 is disposed closer to the center in the thickness direction of the thin battery, the inner area 221 other than the outer peripheral area 222 of the thin battery abuts the fixed surface while the outer peripheral area 222 is , It floats up from the fixed surface. Therefore, the fixation of the thin battery becomes insufficient. When the electronic device is bent in this state, the thin battery peels off or is damaged. Therefore, when the thin battery is bent to fix the outer peripheral region 222 to the fixed surface together with the inner region 221, loads are applied to the inner region 221 of the outer package 220 and the electrode group 210 housed in the outer package. Also in this case, the exterior body 220 and the electrode group 210 may be damaged.

  In view of the above, one aspect of the present invention is a thin battery including an electrode group, a non-aqueous electrolyte impregnated in the electrode group, and an outer package that tightly encloses the electrode group and the non-aqueous electrolyte. The exterior body includes an inner area facing the electrode group and an outer peripheral area other than the inner area when viewed in the normal direction of one main surface of the electrode group, and the outer peripheral area is A first area located at the outermost periphery of the exterior body, a second area adjacent to the inside of the first area, and a third area adjacent to the inside of the second area, the first area being The second region forms a sealing portion, and the thickness H1 of the thin battery in the first region and the thickness H2 of the thin battery in the second region satisfy the relationship of H1 <H2. The third region has a thin portion, and the thin portion of the thin battery in the thin portion And viewed H3, wherein the thickness H2, satisfy the relationship of H3 <H2, and the thickness H1, wherein the thickness H3, satisfy the relationship of H1 <H3, relates thin battery.

  According to the present invention, the thin battery can be stably fixed in the electronic device. Therefore, even when the thin battery is bent, damage to the exterior body and the electrode group is suppressed.

FIG. 1 is a plan view schematically showing a thin battery according to an embodiment of the present invention. It is a top view which shows the exterior body of the same thin battery. It is a longitudinal cross-sectional view in the XX line of the thin battery shown in FIG. It is a longitudinal cross-sectional view in a part of exterior body of the conventional thin battery.

  A thin battery (hereinafter, may simply be referred to as a battery) according to the present embodiment includes an electrode group, a non-aqueous electrolyte impregnated in the electrode group, and an outer package that tightly encloses the electrode group and the non-aqueous electrolyte. including. The exterior body includes an inner region facing the electrode group and an outer peripheral region other than the inner region when viewed in the normal direction of one main surface of the electrode group. The outer peripheral area includes a first area located at the outermost periphery of the outer package, a second area adjacent to the inside of the first area, and a third area adjacent to the inside of the second area.

  The thickness H1 of the battery in the first region and the thickness H2 of the battery in the second region satisfy the relationship of H1 <H2. The third region is provided with a thin portion in which the thickness H3 of the thin battery satisfies the relationship H3 <H2. The thickness H1 in the first region and the thickness H3 in the thin portion of the third region satisfy the relationship of H1 <H3.

  In other words, the outer peripheral region of the outer package includes, from the outside, a third region including a thin first region, a thicker second region and a thin portion (thin portion).

  The sealed portion (sealed portion) of the outer package is formed of a thin first region and a thick second region (H1 <H2). That is, a part (second region) of the sealing portion can be used for fixing to the electronic device. Therefore, the floating part of the outer peripheral area is reduced as compared with the conventional case, and the fixing property of the battery to the fixing surface of the electronic device is improved. This suppresses damage to the outer package and the electrode group when the battery is bent.

  Furthermore, inside the thick second region, a third region (H3 <H2) having a thin portion is disposed. The battery is fixed to the electronic device by the inner region mainly facing the electrode group of the outer package and the second region. Therefore, the bending load that occurs when the battery is bent is absorbed by the particularly thin part of the third region. Thereby, the damage suppression effect of an exterior body and an electrode group is further improved.

  On the other hand, the thin portion of the third region is thicker than the first region (H1 <H3). Usually, the package is sealed by sandwiching at least a part of the outer peripheral area with a pair of heat seal bars and applying heat and pressure. At this time, if a high pressure is applied to the third region to make the thickness excessively small (for example, less than the thickness H1), a large load is likely to remain in the third region. Therefore, the third region is formed without applying an excessive load so as to satisfy H1 <H3. As a result, the load remaining in the third region is reduced, and even when the battery is bent, damage to the third region, which is easily subjected to bending load, is suppressed. It is preferable that at least a part of the thin portion of the third region is not sealed (do not form a sealing portion) in that bending load is easily absorbed. In particular, the thin portion preferably does not form a sealing portion.

  In a preferred embodiment, the thickness H2 in the second region and the thickness H4 of the thin battery in the inner region satisfy the relationship of H2 / H4> 0.5. Thus, the thin battery can be easily fixed to the fixing surface of the electronic device in the second region together with the inner region.

  The width W1 of the first region and the width W2 of the second region may satisfy the relationship of W2 / W1> 0.2. As a result, the thin battery can be more easily fixed to the fixing surface of the electronic device.

  The width W2 of the second region and the width W3 of the third region may satisfy the relationship of 0.1 <W2 / W3 <3. As a result, the effect of fixing the battery in the second region and the effect of absorbing the bending load in the third region can be easily achieved.

  In another preferable embodiment, the central surface in the thickness direction of the third region (hereinafter, referred to as a central surface of thickness) is positioned near the central surface of the thickness of the second region. As a result, the electronic device and the battery fixed to the electronic device are easily bent in the direction in which the battery is on the outer side and in the direction in which the electronic device is on the outer side. Therefore, the damage suppressing effect of the battery is further improved.

  Next, the thin battery according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a plan view schematically showing a thin battery according to the present embodiment. FIG. 2 is a plan view showing an exterior body of the thin battery. FIG. 3 is a longitudinal sectional view taken along line XX of the thin battery shown in FIG.

  The thin battery 100 includes an electrode group 110, a non-aqueous electrolyte (not shown), and an exterior body 120 for housing these. Thin battery 100 further includes a pair of electrode leads 130 connected to electrode group 110 and extending to the outside of package body 120.

The electrode group 110 may be a laminated body in which a sheet-like positive electrode and a negative electrode are stacked, or may be a wound body in which a strip-like positive electrode and a negative electrode are wound.
The sheet-like electrode group 110 includes, for example, one first electrode (positive electrode or negative electrode) and a pair of second electrodes (negative electrode or positive electrode) sandwiching the first electrode, and includes the first electrode and the second electrode. There is a separator between them. Each of the first electrode and the second electrode includes, for example, a current collector sheet and an active material layer attached to at least one surface. In this case, the first electrode may be a double-sided electrode including a current collector sheet and an active material layer attached to both surfaces thereof. On the other hand, the second electrode may be a single-sided electrode including a current collector sheet and an active material layer attached to one surface thereof. Each current collector sheet has a tab extending from one side thereof. One electrode lead 130 is connected to the tab.

  The configuration of the sheet-like electrode group 110 is not limited to this, and for example, two or more first electrodes and three or more second electrodes may be provided. In this case, the first electrode and the second electrode are alternately stacked. The simplest structure of such an electrode group 110 is that two first electrodes, one second electrode interposed between the two first electrodes, and one outside each of the two first electrodes. And second electrodes arranged one by one. Such thin batteries not only have small thickness but also have high capacity. In this case, the first electrode may be a double-sided electrode as described above. One second electrode interposed between the two first electrodes may also be a double-sided electrode. On the other hand, the second electrodes arranged respectively on the outermost side may be single-sided electrodes as described above.

  In FIG. 1, the electrode group 110 and the exterior body 120 are generally rectangular, but the shapes of the electrode group 110 and the exterior body 120 are not limited thereto. The shape of the electrode other than the tab is not particularly limited, and may be rectangular (including square), trapezoidal, parallelogram, substantially elliptical having a straight portion in part, substantially rectangular with at least one of the corners of the rectangle rounded A trapezoid, a substantially parallelogram, etc. are mentioned. In particular, the electrode excluding the tab is preferably shaped to have a straight portion from which the tab protrudes. From the viewpoint of productivity, the electrode excluding the tab is preferably rectangular or substantially rectangular. When the electrode is rectangular or substantially rectangular, the ratio of the length of the long side to the short side is, for example, long side: short side = 1: 1 to 8: 1. Usually, the direction along the long side is the direction in which the tab extends.

  The shape of the exterior body 120 is, for example, a rectangle (including a square), a trapezoid, a parallelogram, a semicircle, a semiellipse, a rectangle with an arc tip at the tip, a substantially rectangle with at least one round corner, a substantially trapezoid, a substantially trapezoid It may be a parallelogram.

  The exterior body 120 includes an inner region 121 facing the electrode group 110 and an outer peripheral region 122 other than the inner region 121 when viewed in the normal direction of one main surface of the electrode group 110. The outer peripheral area 122 includes a first area 122a located at the outermost periphery of the exterior body 120, a second area 122b adjacent to the inside of the first area 122a, and a third area 122c adjacent to the inside of the second area 122b. Equipped with The first region 122a and the second region 122b form a sealing portion. That is, the exterior body is sealed by the first area 122a and the second area 122b.

  The battery thickness H1 in the first region 122a and the battery thickness H2 in the second region 122b satisfy the relationship of H1 <H2. As a result, the second region 122 b can be used for fixing to the electronic device, so the fixability of the battery is improved. The ratio (H1 / H2) of the thickness H1 to the thickness H2 is not particularly limited as long as it is less than 1. H1 / H2 may be, for example, 0.1 or more and less than 1, or 0.2 or more and 0.8 or less. The thicknesses H1 and H2 are the shortest distance between the main surfaces in each region, and are the average distances of any three places.

  The third region 122c includes a thin portion 122ca in which the thin battery thickness H3 satisfies the relationship H3 <H2. The thin portion 122 ca of the third region 122 c between the inner region 121 and the second region 122 b is usually difficult to be fixed to the fixing surface of the electronic device. Thus, the bending load generated when the battery is bent is collected and absorbed in the particularly thin portion 122 ca of the third region 122 c. Thereby, damage to the exterior body 120 and the electrode group 110 is suppressed. The ratio of thickness H3 to thickness H2 (H3 / H2) is not particularly limited as long as it is less than 1. H3 / H2 may be, for example, 0.1 or more and less than 1, or 0.2 or more and 0.8 or less. The thickness H3 is the shortest distance between the main surfaces of the thin portion 122ca, and is the average distance of any three places. The thickness of the thin battery in the third region 122 c other than the thin portion 122 ca may be equal to or less than the thickness (H 4) of the thin battery 100 in the inner region 121.

  The thickness H1 and the thickness H3 satisfy the relationship of H1 <H3. In this case, since the residual load on the third region 122c is small as described above, even when the battery 100 is bent, damage to the third region 122c that is easily subjected to a bending load is easily suppressed. The ratio (H1 / H3) of the thickness H1 to the thickness H3 is not particularly limited as long as it is less than 1. H1 / H3 may be, for example, 0.1 or more and less than 1, or 0.2 or more and 0.8 or less.

  The third region 122c may be a part of the sealing portion, or may not form the sealing portion. It is preferable that at least a part of the thin portion 122 ca of the third region 122 c does not form a sealing portion in that bending load is easily absorbed. In particular, it is preferable that the entire thin portion 122 ca does not form a sealing portion.

  The thickness H2 in the second region 122b and the thickness H4 of the thin battery 100 in the inner region 121 may satisfy the relationship of H2 / H4> 0.5. As a result, the battery is further easily fixed to the fixing surface of the electronic device in the second region 122 b together with the inner region 121. H2 / H4 may be, for example, more than 0.5 and less than 1.6, and may be 0.6 or more and 1.4 or less. The thickness H4 is the shortest distance between the main surfaces in the inner region 121, and is the average distance between any three points.

  The thickness H4 of the battery 100 is not particularly limited. In consideration of the flexibility, the thickness H4 may be 3 mm or less, further 2 mm or less, particularly 1.5 mm or less. The lower limit of the thickness H4 may be, for example, 50 μm.

  The width W1 of the first area 122a and the width W2 of the second area 122b may satisfy the relationship of W2 / W1> 0.2. Thereby, the battery 100 can be more easily fixed to the fixing surface of the electronic device. W2 / W1 may be, for example, 0.25 or more, or 0.3 or more. W2 / W1 may be, for example, 1.5 or less, and may be 1.0 or less.

  The width W2 of the second region 122b and the width W3 of the third region 122c may satisfy the relationship of 0.1 <W2 / W3 <3. As a result, the effect that the second region 122 b fixes the battery 100 and the effect that the third region 122 c absorbs a bending load can easily be compatible. W2 / W3 may be, for example, 0.2 or more and 2.0 or less, and may be 0.3 or more and 1.0 or less. The width of the thin portion 122 ca of the third region 122 c is not particularly limited.

  The width of each region and the thin portion is obtained by a cross section of the package 120 perpendicularly intersecting the outer edge of the package 120 and cut in the thickness direction of the package 120 (hereinafter referred to as the X direction). When the outer edge of the outer package 120 is a straight line, the X direction is a direction perpendicular to the outer edge of the outer package 120 and cutting the outer package 120 in the thickness direction. When the outer edge of the exterior body 120 includes a curve, the X direction is a direction perpendicular to the tangent of the curve and cutting the exterior body 120 in the thickness direction.

The boundary of each area can be determined, for example, as follows.
First, one of the cut pieces obtained by dividing the battery 100 into two in the X direction is placed on a gantry having a horizontal surface. At this time, while bringing the whole of one main surface of the inner region 121 of the cut piece into contact with the horizontal surface, the outer peripheral region 122 is supported so as not to bend. With the spacer interposed between the inner region 121 and the horizontal surface, the whole of one main surface of the inner region 121 may be in contact with the horizontal surface via the spacer. In this state, take a picture of the cross section. For this cross-sectional photograph, a tangent to the main surface of the frame opposite to the one facing the horizontal surface is drawn from the outer edge of the exterior body 120 toward the inner region, and the inclination relative to the horizontal surface is plotted on a graph.

  In this graph, the first point at which the tangent line starts to slope is the boundary between the first area 122a and the second area 122b. Beyond the first point, the slope increases and then gradually becomes gradual. As you go further, the slope is reversed this time. The inverted slope of the tangent becomes gradually gradual. The slope of the tangent then reverses slightly again, or becomes nearly zero. The point (second point) at which the slope changes is the boundary between the second area 122 b and the third area 122 c. The boundary between the third region 122c and the inner region 121 is an intersection point of a straight line extending in a direction perpendicular to the horizontal plane passing through the end of the electrode group 110 and the exterior body 120.

  Beyond the second point, the slightly inclined (or horizontal) tangent line begins to tilt gradually and gradually beyond a certain area. This is for sandwiching the electrode group 110. The area from the second point to when this tangent line starts to tilt greatly is the thin portion 122 ca of the third area 122 c.

  It is preferable that the central plane of the thickness of the third region 122c be located closer to the central plane of the thickness of the second region 122b. Thereby, the electronic device and the battery fixed to this project the third region 122c with the battery 100 inside, even in the direction in which the third region 122c protrudes with the battery 100 outside (upper in FIG. 3) It becomes easy to be bent also in the direction (lower part in FIG. 3) to be made. Thus, the damage suppressing effect of the battery 100 is further improved.

  For example, in FIG. 3, the central plane of the thickness of the third region 122c is a straight line coinciding with one main surface of the third region 122c or a horizontal straight line (first straight line c) that contacts the main surface on the outermost side; A straight line coinciding with the other main surface of the third region 122c or a horizontal straight line (second straight line c) that is outermost on the main surface and a straight line (central line c, none of which is shown) at the center Indicated. The center plane (center line b) of the thickness of the second region 122b can be determined similarly by defining the first straight line b and the second straight line b. Being positioned closer to the central surface of the second region 122b means that the central surface (central line c) of the thickness of the third region 122c is closer to the central line b than the first straight line b (or the second straight line b). Say

  The exterior body 120 only needs to have the first region 122a, the second region 122b, and the third region 122c that satisfy the above relationship, and it is not necessary to satisfy the above relationship in all of the outer peripheral region 122. When the exterior body 120 is rectangular as in the illustrated example, for example, one side of the four sides forming the outer peripheral region 122 may satisfy the above-described relationship. In particular, it is preferable that the longest side includes the first region 122a, the second region 122b, and the third region 122c that satisfy the above relationship. Furthermore, it is preferable that all the four sides of the outer peripheral area 122 satisfy the above relationship. This is because the fixation and the bending resistance of the battery are particularly enhanced.

  Next, the materials of the electrodes, leads, separators, non-aqueous electrolytes, outer package materials, etc. constituting the electrode group will be described by taking a lithium ion battery as an example, but it is not limited thereto. explain.

(Negative electrode)
The negative electrode has a negative electrode current collector sheet and a negative electrode active material layer. A metal film, metal foil or the like is used for the negative electrode current collector sheet. The material of the negative electrode current collector sheet is preferably at least one selected from the group consisting of copper, nickel, titanium and alloys thereof and stainless steel. The thickness of the negative electrode current collector sheet is, for example, 5 to 30 μm.

  The negative electrode active material layer contains a negative electrode active material, and optionally contains a binder and a conductive agent. The negative electrode active material layer may be a deposited film formed by a vapor phase method (for example, vapor deposition). Examples of the negative electrode active material include lithium metal, a metal or alloy that electrochemically reacts with lithium, a carbon material (eg, graphite), a silicon alloy, a silicon oxide, and the like. The thickness of the negative electrode active material layer is, for example, 1 to 300 μm.

(Positive electrode)
The positive electrode has a positive electrode current collector sheet and a positive electrode active material layer. A metal film, metal foil, etc. are used for a positive electrode collector sheet. The material of the positive electrode current collector sheet is preferably at least one selected from the group consisting of, for example, silver, nickel, palladium, gold, platinum, aluminum and alloys thereof and stainless steel. The thickness of the positive electrode current collector sheet is, for example, 1 to 30 μm.

The positive electrode active material layer contains a positive electrode active material and a binder, and optionally contains a conductive agent. The positive electrode active material is not particularly limited, but when the thin battery is a secondary battery, a lithium-containing composite oxide such as LiCoO ₂ or LiNiO ₂ is used. When the thin battery is a primary battery, manganese dioxide is used. Carbon fluoride (graphite fluoride), lithium-containing composite oxide, and the like can be used. The thickness of the positive electrode active material layer is, for example, 1 to 300 μm.

  Graphite, carbon black or the like is used as the conductive agent to be contained in the active material layer. The amount of the conductive agent is, for example, 0 to 20 parts by mass per 100 parts by mass of the active material. As a binder to be contained in the active material layer, fluorocarbon resin, acrylic resin, rubber particles and the like are used. The amount of the binder is, for example, 0.5 to 15 parts by mass per 100 parts by mass of the active material.

(Lead)
The negative electrode lead and the positive electrode lead are respectively connected to the negative electrode current collector sheet or the positive electrode current collector sheet by welding or the like. As a negative electrode lead, a copper lead, a copper alloy lead, a nickel lead or the like is preferably used. As the positive electrode lead, a nickel lead, an aluminum lead or the like is preferably used.

(Separator)
As the separator, a resin microporous membrane or non-woven fabric is preferably used. As a material (resin) of a separator, polyolefin (polyethylene, a polypropylene etc.), polyamide, a polyamide imide etc. are preferable. The thickness of the separator is, for example, 8 to 30 μm.

(Non-aqueous electrolyte)
When the thin battery is a lithium ion battery, a mixture of a lithium salt and a non-aqueous solvent in which the lithium salt is dissolved is preferable as the non-aqueous electrolyte. Examples of lithium salts include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , and imido salts. As the non-aqueous solvent, cyclic carbonates such as propylene carbonate, ethylene carbonate and butylene carbonate, linear carbonates such as diethyl carbonate, ethyl methyl carbonate and dimethyl carbonate, cyclic carboxylic acid esters such as γ-butyrolactone and γ-valerolactone Etc.

(Exterior body)
The exterior body is formed of, for example, a laminate film having a barrier layer against water vapor and a resin layer formed on both sides thereof.
The material used for the barrier layer is not particularly limited, but it is preferable to use a metal layer, a ceramic layer or the like. For example, metal materials such as aluminum, titanium, nickel, iron, platinum, gold, and silver, and ceramic materials such as silicon oxide, magnesium oxide, and aluminum oxide are preferable. The thickness of the barrier layer is, for example, 0.01 to 50 μm.

  The material of the resin layer disposed on the inner surface side of the outer package is a polyester such as polyethylene and polypropylene such as polyethylene and polypropylene, a polyester such as polyethylene terephthalate and polybutylene terephthalate from the viewpoints of heat welding easiness, electrolytic resistance and chemical resistance. And polyamide, polyurethane, polyethylene-vinyl acetate copolymer (EVA) and the like. The thickness of the resin layer on the inner surface side is, for example, 10 to 100 μm.

  The resin layer disposed on the outer surface side of the outer package is preferably a polyamide such as 6,6-nylon, a polyolefin, a polyester or the like from the viewpoints of strength, impact resistance and chemical resistance. The thickness of the resin layer on the outer surface side is, for example, 5 to 100 μm.

The battery 100 is manufactured, for example, as follows.
First, the electrode group 110 to which each electrode lead 130 is connected is prepared (first step).
Separately, a bag-like exterior body 120 partially opened is prepared (second step).
Next, the electrode group 110 is accommodated in the outer package 120 so that the end of each electrode lead 130 is drawn out from the opening of the outer package 120, and the non-aqueous electrolyte is impregnated into the electrode group 110 under reduced pressure (third step) ).
Finally, the opening of the package 120 is sealed with the leads interposed (fourth step).

  In the second step, heat and pressure are applied excluding a part of the outer peripheral region in a state in which the material of one package is folded or in a state in which the materials of two packages are laminated. , Sealing step (first sealing step) is included. Further, the fourth step includes a step (second sealing step) of applying heat and pressure to a part of the open outer peripheral region of the exterior body 120 for sealing.

  In at least one of the first sealing step and the second sealing step, the outer peripheral region 122 is sealed using a pair of sealing molds having one step. The shape of the step portion is not particularly limited, and may be appropriately set according to the desired shape of the outer peripheral region 122.

  In the sealing step, the area where the mold spacing is smaller when the molds face each other corresponds to the outer edge of the exterior body 120, and the area where the mold spacing is larger corresponds to the inner side of the exterior body 120. . When the material of the exterior body 120 is a laminate film as described above, the resin layer on the inner surface side and / or the outer surface side disposed at a position corresponding to the outer edge of the exterior body 120 is the exterior body by heat and pressure. It flows to the area inside 120. Thereby, a thin first region 122a is formed, and a thicker second region 122b is formed. That is, in this case, the second region 122 b includes a thick resin layer formed of the flowing resin. On the other hand, no pressure is applied to the area further inside of the package 120 (the area further inside than the area where the thick resin layer is formed). As a result, the area (third area 122c) located inside the second area 122b is difficult to seal, and is thinner than the second area 122b and thicker than the first area 122a. For example, the third region 122 c has a thickness equal to the thickness of two sheets of the exterior body 120.

  When the material of the exterior body 120 does not have the above resin layer or has a thin resin layer, after a separate seal member including the material of the resin layer is disposed near the outer edge of the exterior body 120, It may be sealed. As a result, the thin first region 122a, the thicker second region 122b, and the relatively thin third region 122c are formed as described above.

  According to the method of sandwiching the outer edge of the exterior body 120 from both sides with a mold having a step, since a plurality of regions having different thicknesses can be simultaneously formed, productivity is high. Battery 100 may be manufactured by cup molding in which a part of the exterior body is molded in a cup shape in advance. Gold having a stepped portion in that productivity is high and it is easy to position the central surface of the thickness of the third region 122c near the central surface of the thickness of the second region 122b in the thickness direction of the battery 100 The method of sandwiching the outer edge of the exterior body 120 from both sides with a mold is more suitable.

  The heating temperature and pressure in each sealing step are not particularly limited, and may be appropriately set according to the material of the exterior body 120. For example, the heating temperature in each sealing step may be 120 to 200 ° C., and the pressure may be 0.1 to 10 MPa.

  The thin battery according to the present embodiment is fixed to, for example, a flexible electronic device driven by power supply from the thin battery, and is used by being integrated. As an electronic device integrated with a thin battery, for example, a biomedical device or wearable portable terminal, a mobile phone, a voice recording and reproducing device, a wrist watch, a moving image and still image shooting device, a liquid crystal display, a calculator, an IC card , Temperature sensors, hearing aids, pressure sensitive buzzers, etc. Examples of the bioadhesive device include a biological information measurement device, an iontophoretic transdermal drug delivery device, and the like.

Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.
Example 1
The thin battery which has a pair of negative electrodes and the positive electrode pinched | interposed into these was produced with the following procedures.
(1) Preparation of Negative Electrode An electrolytic copper foil having a thickness of 8 μm was prepared as a negative electrode current collector sheet. The negative electrode mixture slurry was applied to one surface of the electrodeposited copper foil, dried, and rolled to form a negative electrode active material layer, whereby a negative electrode sheet was obtained. The negative electrode mixture slurry is prepared by mixing 100 parts by mass of graphite as a negative electrode active material, 8 parts by mass of polyvinylidene fluoride (PVdF) as a binder, and an appropriate amount of N-methyl-2-pyrrolidone (NMP). Prepared. The thickness (per one surface) of the negative electrode active material layer was 54 μm. A 47.5 mm × 18 mm negative electrode having a 5 mm × 5 mm negative electrode tab was cut out from the negative electrode sheet, and the active material layer was peeled off from the negative electrode tab to expose the copper foil. Thereafter, a copper negative electrode lead was ultrasonically welded to the tip portion of the negative electrode tab of one negative electrode.

(2) Production of Positive Electrode An aluminum foil having a thickness of 15 μm was prepared as a positive electrode current collector sheet. The positive electrode mixture slurry was applied to both surfaces of the aluminum foil, dried, and rolled to form a positive electrode active material layer, whereby a positive electrode sheet was obtained. The positive electrode mixture slurry is prepared by mixing 100 parts by mass of lithium cobaltate as a positive electrode active material, 1.2 parts by mass of acetylene black as a conductive agent, 1.2 parts by mass of PVdF as a binder, and an appropriate amount of NMP. Prepared. The thickness (per one side) of the positive electrode active material layer was 37 μm. A 45 mm × 16 mm positive electrode having a 5 mm × 5 mm tab was cut out from the positive electrode sheet, and the active material layer was peeled off from the positive electrode tab to expose the aluminum foil. Thereafter, the positive electrode lead made of aluminum was ultrasonically welded to the front end portion of the positive electrode tab.

(3) Preparation of Nonaqueous Electrolyte LiPF ₆ was dissolved in a mixed solvent containing ethylene carbonate (EC) and diethyl carbonate (DEC) as main components to prepare a non-aqueous electrolyte.

(4) Preparation of Electrode Group A positive electrode was disposed between a pair of negative electrodes via a separator so that the negative electrode active material layer and the positive electrode active material layer face each other, to form an electrode group. For the separator, a 49 mm × 18 mm size microporous polyethylene film (15 μm in thickness) was used.

(5) Preparation of Outer Body and Assembly of Battery A laminate film material (73 μm in thickness) in which a barrier layer of aluminum foil intervenes between two polyethylene layers (30 μm in thickness) was used as a material of the outer body. The laminate film material was cut into a 29 mm × 120 mm rectangle and folded in half at the center in the longitudinal direction.

  Next, the electrode group was sandwiched by the folded laminate film material, and each lead of the electrode group was led out from the opposite side of the fold. Subsequently, the three sides except the side opposite to the fold are pressed with a sealing die having a step to form an envelope-like exterior body in a state of accommodating the electrode group, and One area, a second area and a third area were formed.

  A non-aqueous electrolyte was injected from the opening of the envelope-like outer package 120, and the opening was pressed and sealed with a sealing mold of the same type as described above under a reduced pressure of -650 mmHg. Thereafter, the thin battery was aged at 45 ° C. to impregnate the whole electrode assembly with the non-aqueous electrolyte. Finally, the battery was pressed at 25 ° C. for 30 seconds under a pressure of 0.25 MPa to produce a battery A1 having a thickness of 0.4 mm. The first region, the second region, and the third region were also formed on the other side of the exterior body.

[Evaluation]
(Fixation of thin battery)
A pair of expandable fixing members are horizontally disposed to face each other, and the battery A1 in a discharged state is attached and fixed to each fixing member. Then, after reducing the distance between both ends of the fixing member so that the curvature radius of the battery is R30 mm under an environment of 25 ° C., both ends of the fixing member were returned again, and the battery was returned to a flat state. This bending operation was repeated until the thin battery peeled from the fixing member. Table 1 shows the number of bending when the thin battery is peeled off.

(Damage of thin battery)
After the thin battery was peeled off from the fixing member, it was visually confirmed whether or not the outer package has a crack. The results are shown in Table 1 together.

<< Examples 2-5, comparative example 1 >>
Batteries A2 to A5 and B1 were produced and evaluated in the same manner as in Example 1 except that the thicknesses and widths of the first region, the second region, and the third region were as shown in Table 1. The results are shown in Table 1. In Example 2, the thickness (per one side) of the positive electrode active material layer was 67 μm, and the thickness (per one side) of the negative electrode active material layer was 97 μm.

Comparative Example 2
A battery B2 was produced and evaluated in the same manner as in Example 1 except that a mold having no step was used. The results are shown in Table 1.

  As shown in Table 1, in the batteries A1 to A5, the number of bendings until peeling was large and damage to the outer package did not occur, whereas in the batteries B1 and B2, the number of bendings was small, and the outer package Damage was also occurring.

  The thin battery of the present invention is suitable, for example, for use in a small electronic device such as a biomedical device or a wearable portable terminal.

100: Thin battery 110: Electrode group 120: Case 121: inner region 122: outer region 122a: first region 122b: second region 122c: third region
122ca: Thin portion 130: Electrode lead 210: Electrode group 220: Case 221: Inner region 222: Outer peripheral region

Claims (7)

An electrode group,
A non-aqueous electrolyte impregnated in the electrode group;
It is a thin battery containing the said electrode group and the exterior body which carries out airtight accommodation of the said non-aqueous electrolyte, Comprising:
The exterior body includes an inner region facing the electrode group and an outer peripheral region other than the inner region when viewed in the normal direction of one main surface of the electrode group.
The outer circumferential area is
A first region located at the outermost periphery of the exterior body,
A second area adjacent to the inside of the first area;
And a third area adjacent to the inside of the second area,
The first region and the second region form a sealing portion,
The thickness H1 of the thin battery in the first region and the thickness H2 of the thin battery in the second region satisfy the relationship of H1 <H2;
The third region has a thin portion,
The thickness H3 of the thin battery and the H2 in the thin portion satisfy the relationship of H3 <H2,
The thin battery, wherein the thickness H1 and the thickness H3 satisfy the relationship of H1 <H3.   The thin battery according to claim 1, wherein the thickness H2 and the thickness H4 of the thin battery in the inner region satisfy the relationship of H2 / H4> 0.5.   The thin battery according to claim 1 or 2, wherein the width W1 of the first region and the width W2 of the second region satisfy the relationship of W2 / W1> 0.2.   The thin battery according to any one of claims 1 to 3, wherein the width W2 of the second region and the width W3 of the third region satisfy the relationship of 0.1 <W2 / W3 <3.   The thin battery according to any one of claims 1 to 4, wherein at least a part of the thin portion of the third region does not form the sealing portion.   The thin battery according to any one of claims 1 to 5, wherein a surface of a center in the thickness direction of the third region is positioned near a surface of a center in the thickness direction of the second region. The thin battery according to any one of claims 1 to 6, wherein a thickness H4 of the thin battery in the inner region is 2 mm or less.

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