JP2000353499A - Thin battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin and lightweight battery having improved connection reliability of external terminals. SOLUTION: This thin battery is provided with a unit cell 2 constituted of a sheet-like positive electrode and a sheet-like negative electrode laminated and arranged on the principal plane of the sheet-like positive electrode via a sheet-like separator having ionic conductivity, and an exterior film 1 extending external terminals 3, 4 corresponding to the positive and negative electrodes of the unit cell 2 and liquid-tightly sealing a seal section 1a to the unit cell 2 via heat welding of heat welding resins. The external terminals 3, 4 are located in the seal section 1a of the exterior film 1, and openings 1b with a recessed cross section are provided in the extending direction of the external terminals 3, 4 so that the external terminals 3, 4 can be inserted or coupled with corresponding connecting terminals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin battery,
More specifically, the present invention relates to a thin battery in which external connection terminals are mechanically reinforced.

[0002]

2. Description of the Related Art As power sources for portable telephones, television cameras, and the like, small, lightweight, thin, large-capacity, and high-voltage power sources are required, and a positive electrode layer, a polymer electrolyte layer, and a negative electrode layer are required. A polymer lithium battery having a thickness of about 0.5 mm provided with stacked unit cells (stacks) or a stack of unit cells is also known (for example, US Patent No.
5,296,318).

FIGS. 6 and 7 show the configuration of a main part of a conventional thin battery. FIG. 6 is a perspective plan view, and FIG.
FIG. 4 is a cross-sectional view along the line AA ′. 6 and 7, 1 is an exterior film, 2 is a unit cell, 3 is one end connected to the positive electrode of the unit cell, and the other end is a positive external terminal liquid-tightly drawn out of the exterior film 1 (external connection). Terminals 4) are negative external terminals (external connection terminals), one end of which is connected to the negative electrode of the unit cell and the other end of which is led out of the exterior film 1 in a liquid-tight manner.

Here, the unit cell 2 is a sheet-shaped negative electrode.
2a, sheet-like separator carrying electrolyte on both main surfaces
The configuration is such that the sheet-shaped positive electrode 2c is stacked and arranged via the 2b. The sheet-like negative electrode 2a is composed of, for example, an active material that stores and releases lithium ions, an electrolyte-retaining polymer, and a negative electrode current collector.

[0005] The sheet-like separator 2b is a polymer-electrolyte system such as an electrolyte-retaining polymer such as a hexafluoropropylene-vinylidene fluoride copolymer.
Further, the sheet-shaped positive electrode 2c is composed of an active material such as a metal oxide containing lithium, an electrolyte-retaining polymer, and a positive electrode current collector.

More specifically, a sheet-shaped negative electrode 2a is provided on a projecting / extending portion of a negative electrode current collector (eg, copper foil, punched metal, expanded metal) with a copper foil having a thickness of about 0.05 to 0.2 mm. One end of the piece 4 is welded and connected to provide a negative external terminal (external connection terminal). Further, the sheet-shaped positive electrode 2c is
At the projecting / extending portion of the positive electrode current collector (for example, aluminum foil, punched metal, expanded metal), a thickness of 0.05
One end of an aluminum foil piece 3 of about 0.2 mm is welded and connected to provide a positive external terminal (external connection terminal).
Then, the sheet electrodes 2a and 2c and the sheet separator 2b are laminated as described above to form the unit cell 2.

Further, the exterior film 1 employs a structure in which the unit cell 2 is sealed in a liquid-tight or air-tight manner. However, the positive and negative external terminals 3 and 4 are separated from each other and are collectively liquid-tight or air-tight. While being sealed and led out, it extends outside the sealed body formed by the exterior film 1. The manufacture of such a lightweight and flexible thin battery is generally performed in the following procedure.

First, the sheet-like negative electrode 2a, sheet-like separator (polymer-electrolyte) 2b and sheet-like positive electrode 2c
Are combined in a stack to form a unit cell 2. After that, the corresponding external terminal pieces 3 and 4 are aligned and welded to the projecting / extending portions of the current collector provided in the sheet electrodes 2a and 2c of the unit cell 2 respectively.

Next, the exterior film 1 is laminated on both sides.
While arranging (bending one resin film or facing two resin films so as to wrap both main surfaces), the external terminals 3 and 4 connected to the current collector are separated and led out to the outside. Meanwhile, the opposing peripheral portions of the exterior film 1 are joined and integrated via heat fusion (thermal welding) or an adhesive layer, and are sealed in a liquid-tight or air-tight manner.

[0010] Here, as the exterior film, an aluminum foil is used as an inner layer in order to prevent the penetration and penetration of moisture, and a heat-sealing or bonding surface is formed on a heat-sealing resin layer (by using a modifying group such as maleic anhydride as a modifying group). A multilayer film formed of a resin layer included therein is preferable. Note that a predetermined amount of electrolyte is injected into the unit cell 2 before the joining / integration process, that is, before the whole is liquid-tightly or air-tightly sealed.

[0011]

However, in the case of the thin battery having the above structure, there are the following disadvantages. In other words, in making the thin battery of the above configuration thinner and lighter, the thickness of the outer film is made as thin as possible,
4 also performs liquid-tight or air-tight sealing, but there is a problem that the external terminals 3 and 4 extending outside the exterior film 1 are liable to be bent or deformed in a handling process or the like.

Here, the deformability of the external terminals 3 and 4 protruding and arranged from the exterior sealing body may not only cause a contact (short circuit) between the external terminals 3 and 4 but also, for example, a secondary It is difficult to make the contact terminals contact with the external terminals 3 and 4 with high accuracy in the charge and discharge process and the tester process in the battery manufacturing process. To raise. On the other hand, the external terminals 3 and 4 protrude from the exterior sealing body,
This means that miniaturization of the thin battery is hindered. That is, the efficiency of the volume energy density is reduced.

The problem that the external terminals 3 and 4 are easily deformed is that when the thin battery is mounted on the device and the protective element is attached to the external terminals 3 and 4 by welding or the like, the external terminals 3 and 4 are not easily deformed. , 4 and the external terminals 3,
Fourth part Mechanical strength is a concern.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a thin battery having a reduced size and weight, and improved connection reliability of external terminals.

[0015]

According to a first aspect of the present invention, there is provided a unit comprising a sheet-like positive electrode, and a sheet-like negative electrode laminated and arranged on a main surface of the sheet-like positive electrode via a sheet-like separator having ion conductivity. A thin film having a cell and an external film extending external terminals corresponding to the positive and negative electrodes of the unit cell, and a sealing portion for sealing the unit cell in a liquid-tight manner by heat-sealing the heat-fusible resins. Type battery,
The thin battery according to claim 1, wherein the external terminals are in a sealing portion formed by an exterior film, and the extending direction of the external terminals is open in a concave cross-section so that the external terminals can be fitted or engaged with the corresponding connection terminals. It is.

According to a second aspect of the present invention, in the thin battery according to the first aspect, the exterior film is a multilayer type having a metal foil as an inner layer.

That is, according to the first and second aspects of the present invention, in the configuration of a thin battery in which unit cells are sealed with an exterior film, a fusion-sealing area in which extending external terminals are concave in cross section of the exterior film. The main point is that the external terminal is exposed in the concave-shaped cross-sectional area in the fusion-sealing / fixing area, and the external terminal is configured to be connected to the corresponding connection terminal. And

In the first and second aspects of the present invention, the current collector of the sheet-shaped positive electrode is, for example, aluminum foil, aluminum mesh, aluminum expanded metal, aluminum punched metal, titanium, a titanium alloy, or the like. Then, the positive electrode active material is applied to the entire surface of the current collector except for the terminal portion. To form the terminal portion, an aluminum foil piece or the like is welded as an external terminal.

On the other hand, the sheet-shaped negative electrode is made of, for example, copper foil, copper expanded metal, copper punch metal, nickel,
Nickel alloy, stainless steel, etc. are used as the current collector.
Then, the negative electrode active material is applied to the entire surface of both sides of the current collector except for the terminal portion. In addition, a copper foil piece or the like is welded as an external terminal to the current collector forming the terminal portion.

In the first and second aspects of the present invention, the positive electrode active material on which the sheet-shaped positive electrode is adhered and supported is a lithium-containing metal oxide that absorbs and releases lithium ions, such as a lithium-manganese composite oxide and a lithium-containing cobalt oxide. , Lithium-containing nickel cobalt oxide, lithium-containing amorphous vanadium pentoxide, manganese dioxide, chalcogen compounds, and the like.

The negative electrode active material that the sheet-shaped negative electrode adheres and carries is one that absorbs and releases lithium ions, and examples thereof include fired products of bisphenol resin, polyacrylonitrile, and cellulose, and fired products of coke and pitch. These may take the form containing natural or artificial graphite, carbon black, acetylene black, Ketjen black, nickel powder, nickel powder and the like.

Further, the electrolyte which is impregnated and supported by the separator interposed between the above-mentioned sheet-like positive electrode and negative electrode to form an ion conductor is, for example, ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, etc. Lithium perchlorate, lithium hexafluorophosphate, lithium borotetrafluoride, lithium arsenide hexafluoride, lithium trifluoromethanesulfonate, etc. in a nonaqueous solvent such as diethyl carbonate, methyl ethyl carbonate, etc. Dissolved to an extent. Here, examples of the electrolyte-holding polymer-electrolyte system that functions as a separator include polymers such as hexafluoropropylene-vinylidene fluoride copolymer.

In the first and second aspects of the present invention, the exterior film for integrally sealing the unit cell (battery element portion) comprises:
Although not particularly limited, the following multilayer type is preferable. That is, the heat-fusible resin layer is used as the surface to be bonded (the surface to be sealed),
Multi-layer thickness with metal foil inside for moisture proof etc.
A film of about 0.05 to 0.2 mm is preferred.

More specifically, for example, a 10-mm-thick polypropylene resin modified with an acid such as maleic anhydride is used.
~ 150μm heat fusible resin layer, polyethylene terephthalate resin film about 5 ~ 20μm thick, thickness 5 ~
80μm thin aluminum foil and thickness 5-20μ
m is obtained by sequentially laminating and integrating polyethylene terephthalate resin films of about m. Here, instead of the acid-modified polypropylene resin, an ionomer resin,
A urethane resin film, a polyimide resin film, a polystyrene resin film may be used instead of the polyethylene terephthalate resin film, and a copper foil, a nickel foil, or the like may be used instead of the aluminum foil.

It is desirable that the opening (notch) having a concave cross section of the extension region of the external terminal be stepped at a corresponding portion or a side including the portion prior to the sealing of the unit cell. Here, in the heat-sealing / sealing area by the exterior film, the external terminals that extend are fused and sealed, while the opening having a concave cross section that exposes the front end side is the standard / dimension of the thin battery. Although it depends on such factors, it is set so as to at least perform a required function as an external terminal.

In the above-mentioned multilayer film, the polyethylene terephthalate resin film contributes to the reinforcing property of the unit cell in the multilayer outer layer film itself. Here, the thickness of the heat-fusible resin layer is set in consideration of the state of the joining / sealing region surface, specifically, flatness and unevenness difference, where the opposing surfaces are fused together. The liquid-tight or airtight sealing with the exterior film is easily performed by heat-sealing the edges of the exterior film positioned and arranged on both sides of the unit cell by heating, beam irradiation, or the like.

According to the first aspect of the present invention, the external terminals extending from the unit cell are not only sealed and fixed by the exterior film, but also exposed to the region where the distal end of the external terminal is opened in a concave cross section. Has adopted a structure. That is, as a whole, while securing the same size and shape, the external terminal is exposed to the opening of the exterior film in a form that can be fitted or engaged with the corresponding connection terminal to perform a connection function with the outside. It is configured as follows. In this way, the external terminals are mechanically reinforced by fusing and sealing at both ends, eliminating the risk of deformation such as bending and the possibility of short-circuiting. Can be contacted. In addition, there is no fear of damage or occurrence in handling operation due to the external terminal portion.

According to the second aspect of the present invention, the exterior film is formed into a multilayer having excellent moisture-proof properties, so that the outer film can be more effectively used.
The above action is promoted.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described below with reference to FIGS.

Preparation of Sheet-Shaped Positive Electrode Lath metal having a width of 40 mm, a length of 70 mm, a thickness of 40 to 60 μm, and a protrusion having a width of 10 mm and a length of 10 mm as a lead portion was used as a positive electrode current collector. A sheet-shaped positive electrode was produced by such means. That is, lithium-containing cobalt oxide (LiCoO ₂ ) 56% by weight, carbon black 5% by weight, vinylidene fluoride-hexafluoropropylene copolymer (VdF-HFP) powder 17% by weight, and dibutyl phthalate (DBP) 22% by weight Was mixed in acetone to prepare a positive electrode paste. Next, this positive electrode paste was applied to the surface of the polyethylene terephthalate resin film so as to have a thickness of 100 μm, and was carried on the porous current collector to produce a sheet-shaped positive electrode.

Preparation of sheet-like negative electrode Copper having a width of 44 mm, a length of 74 mm, a thickness of 40 to 60 μm, and a lead having a protrusion of 10 mm in width and 10 mm in length was used as a negative electrode current collector. A sheet-shaped negative electrode was produced by means.
58% by weight of mesofused pitch-based carbon fiber, 17% by weight of vinylidene fluoride-hexafluoropropylene copolymer powder, and 25% by weight of dibutyl phthalate were mixed in Ascenton to prepare a paste for a negative electrode. Next, this negative electrode paste was applied on the surface of the polyethylene terephthalate resin film so as to have a thickness of 100 μm, and was carried on the current collector to produce a sheet-shaped negative electrode.

Preparation of Solid Polymer Electrolyte Material 33.3% by weight of silica (SiO ₂ ) powder, 22.2% by weight of vinylidene fluoride-hexafluoropropylene copolymer powder,
And 44.5% by weight of dibutyl phthalate were mixed in Ascenton to prepare a paste. Next, apply this paste to the polyethylene terephthalate resin film
m to obtain a lithium ion conductive polymer electrolyte (solid polymer electrolyte material).

Preparation of Non-Aqueous Electrolyte LiPF ₆ (electrolyte) is dissolved at a ratio of 1 mol / l in a mixed solvent (non-aqueous solvent) of ethylene carbonate and dimethyl carbonate at a volume ratio of 2: 1 to prepare a non-aqueous electrolytic solution. did.

The nonaqueous electrolyte prepared as described above was impregnated and held in the seed-shaped positive electrode, sheet-shaped negative electrode, and solid polymer electrolyte material prepared as described above. Prior to the impregnation of the nonaqueous electrolyte, the sheet-shaped positive electrode, the sheet-shaped negative electrode, and the solid polymer electrolyte material were immersed in methanol to elute and remove the dibutyl phthalate component to form a porous structure.

Next, on both main surface sides of the sheet negative electrode,
A sheet-like positive electrode was positioned and laminated via a solid polymer electrolyte material to produce a unit cell. Then, a 0.1 mm thick piece of aluminum foil, 0.1 mm thick, forming an external terminal is placed on the projecting (extending) part of the current collector that forms the terminal part of the unit cell.
The copper foil pieces of mm are mechanically and electrically joined by welding or the like.

On the other hand, an acid-modified polypropylene resin film having a thickness of about 50 μm, a polyethylene terephthalate resin film having a thickness of about 15 μm,
The external terminals are attached to the acid-modified polypropylene resin film surface of a multi-layer exterior film with a thickness of 0.1 mm and an external dimension of 190 x 65 mm, which is formed by laminating and integrating an aluminum foil of approximately μm and a polyethylene terephthalate resin film of approximately 15 μm in thickness. The unit cell (battery element portion) from which the battery extends was positioned and arranged, and was bent (turned back) at the center in the long side direction. Note that the exterior film for covering and sealing the unit cell had cut off a part of the acid-modified polypropylene resin film layer at the both ends in the length direction (the direction in which the external terminals extend).

Next, the tip of the extended external terminal was left, and the inside of the side and the other opening were sealed by heat fusion to a width of 10 mm. In other words, the side where the external terminal is extended by the seal bar whose temperature is adjusted to 210 ° C,
Hold both edges in the width direction of the exterior film with the unit cell inside, pressurize at 20-13 kgf / cm ² for 7-5 seconds,
The periphery of the opening is heat-sealed to have a thickness of 0.8 mm and a length of 95 mm.
A thin battery with a width of 65 mm and a width of 65 mm was manufactured.

Next, after performing the constant current / constant voltage charging and the constant current / constant voltage discharging on the manufactured thin battery, a part of the fusion-sealed area is opened, and degassing is performed in a reduced pressure chamber. After that, the inside of the opening is again sandwiched with a seal bar temperature-controlled to 210 ° C., pressurized at 13 kgf / cm ² for 5 seconds, heat-sealed to a width of 5 mm, and sealed. A battery was manufactured.

FIG. 1 is a perspective plan view of the main structure of the thin battery manufactured as described above, FIG. 2 is a cross-sectional view taken along the line BB 'of FIG. 1, and FIG. The cross-section is shown along the 'line. 1 to 3, reference numeral 1 denotes an outer layer film, 2 denotes a unit cell, 3 denotes a positive electrode external terminal (terminal for external connection), and 4 denotes a negative electrode external terminal (terminal for external connection). Here, both external terminals 3 and 4 extending from the unit cell 2 are in the fusion / sealing region 1a of the exterior film 1. That is, the unit cell 2 side is sealed and fixed by the fusion / sealing portion 1a of the exterior film 1, and the front end side is exposed to the fusion / sealing portion of the exterior film 1 having an opening 1b having a concave cross section.

According to the fusion / sealing structure of the lead-out portions of the external terminals 3, 4, the external terminals 3, 4 connected to the unit cell 2 and led out are entirely fused to the exterior film 1.・ Because it is inside the sealing portion 1a, it is protected against the force from the outside, while it is exposed to the opening 1b having a concave cross-section formed in the sealing film 1a. Electrical connection is made by fitting or engaging with the terminal.

The unit cell 2 has a configuration in which a sheet-like positive electrode 2c is laminated and arranged on both main surfaces of a sheet-like negative electrode 2a via a sheet-like separator 2b that supports an electrolytic solution.

In the case of the thin battery (polymer lithium secondary battery) having the above structure, the external terminals 3 and 4 which are liable to be deformed or the like are formed.
Is fixed and held by the fusion / sealing portion of the exterior film. That is, the external terminals 3 and 4 are exposed at the cross-section opening formed at the outer end side of the sealing portion so that the distal end portions thereof can be connected to the corresponding connection terminals, and function to connect to the outside. The external terminals 3 and 4 are entirely protected by the exterior film 1.
Because it is reinforced, bending deformation, breakage and damage are eliminated, and the high-quality polymer lithium secondary battery functions as a city hand.

FIGS. 4 and 5 are cross-sectional views showing the main components of a thin battery according to another different embodiment. That is, FIG. 4 shows a case in which a part of the acid-modified polypropylene resin film layer of the exterior film 1 from which the external terminals 3 and 4 are led out is cut off in advance, and the edge of the fusion / sealing portion 1a is formed into a band shape and a cross section. It has a concave opening.

FIG. 5 shows an example of a structure in which the arrangement and lead-out of the external terminals 3 and 4 are offset. That is, basically, FIG.
3 is the same fusion-sealing structure as that shown in FIG. 3, but depending on the use environment or use conditions of the thin battery, the arrangement and derivation of the external terminals 3 and 4 may be restricted, The external terminals 3 and 4 are examples in which the external terminals 3 and 4 can be arranged and derived asymmetrically with respect to the center line in the width direction of the thin battery. And in the case of these modifications, the same operation and effect as described above can be obtained.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. For example, in the configuration of the unit cell, the sheet-shaped positive electrode, the solid polymer electrolyte material (separator sheet), and the sheet-shaped negative electrode may have other material combinations, shapes, dimensions, and the like, and the outer film may have a different shape. However, the present invention is not limited to the multilayer exterior film.

[0046]

According to the first and second aspects of the present invention, the unit cell and the external terminal are hermetically sealed, the bending and the like of the external terminal are eliminated, and a reliable electric connection can be formed. Thin battery is provided. In other words, it is possible to easily perform the required electrical work by attaching / detaching / attaching to / from the equipment, and at the same time, it is highly reliable, thin and lightweight, which eliminates contact between external terminals (occurrence of short circuit) and damage to external terminals. A battery is provided.

[Brief description of the drawings]

FIG. 1 is a perspective plan view showing a main configuration of a thin battery according to a first embodiment.

FIG. 2 is a sectional view taken along the line BB 'of FIG.

FIG. 3 is a sectional view taken along the line CC ′ of FIG. 1;

FIG. 4 is a sectional view showing a configuration of a main part of a thin battery according to a second embodiment.

FIG. 5 is a cross-sectional view showing a main configuration of a thin battery according to a third embodiment.

FIG. 6 is a perspective plan view showing a configuration of a main part of a conventional thin battery.

FIG. 7 is a sectional view taken along line AA ′ of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exterior film 1a ... Fusion / sealing part 1b ... Concave concave opening part of fusion / sealing part 2 ... Unit cell 2a ... Sheet negative electrode 2b ... Separator 2c ... Sheet positive electrode 3 , 4 ... external terminal (external connection terminal)

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 5H011 AA01 AA04 AA06 AA17 CC02 CC06 CC10 DD13 EE04 FF04 GG09 HH02 JJ25 5H022 AA09 BB12 CC03 CC14 CC27 EE03 EE04 5H024 AA02 AA12 BB14 CC04 CC16 CC19 DD01 FF03 DD19 FFFF DD19 GG01 5H029 AJ03 AJ11 AJ15 AK02 AK03 AL06 AL07 AM03 AM04 AM05 AM07 AM16 BJ04 BJ12 CJ05 DJ02 DJ05 EJ01 EJ12

Claims (2)

[Claims] 1. A unit cell comprising a sheet-like positive electrode, a sheet-like negative electrode laminated and arranged on a main surface of the sheet-like positive electrode via a sheet-like separator having ion conductivity, and positive and negative electrodes of the unit cell An external film corresponding to the external terminal, and an external film that seals the unit cell in a liquid-tight manner by heat-sealing the heat-fusible resin between the sealing portions, and the external terminal, A thin battery, wherein the battery is located in a sealing portion formed by an exterior film, and the extension direction of the external terminal is open in a concave cross section so that the external terminal can be fitted or engaged with the corresponding connection terminal. 2. The thin battery according to claim 1, wherein the exterior film is a multilayer type having a metal foil as an inner layer.