JP2000082495A - Solid electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain metal Li from depositing on the surface of a negative electrode and to prevent the internal short circuit of a battery by setting at least the widthwise dimension of the negative electrode of a laminated electrode body to be larger than that of the positive electrode, and forming both widthwise ends of the negative electrode into a shape which protrudes from both widthwise ends of the positive electrode. SOLUTION: When a laminated electrode body 2 is formed into a wound structure, it is shaped into a form where both widthwise ends 6a of a negative electrode 6 protrude from both widthwise ends 7a of a positive electrode 7. In this case, both the ends 6a of the negative electrode is set larger than each of both the ends 7a of the positive electrode by ΔW. The length ΔW of each of the widthwise protrude parts of the negative electrode 6 is preferably set to 0.5-2 mm. When the ΔW is less than 0.5 mm, dendrite deposition at both the ends 6a of the negative electrode increases, so that internal short circuitings increase. When the ΔW exceeds 2 mm, volume energy density is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte battery using a solid or gel polymer material as an electrolyte.

[0002]

2. Description of the Related Art In recent years, with the miniaturization, portableness, and high performance of electronic devices, it is strongly desired that secondary batteries be miniaturized and increased in capacity as power supplies for these electronic devices. I have. Conventionally, lead storage batteries, nickel cadmium batteries, and the like have been used as secondary batteries. As new secondary batteries, nickel-metal hydride batteries and lithium-ion batteries have been put to practical use.

[0003] However, these secondary batteries have a problem of liquid leakage because a liquid non-aqueous electrolyte is used. As an effective solution for the secondary battery, a so-called solid electrolyte battery using a solid or gel polymer material as an electrolyte has been proposed. As a typical solid electrolyte battery, there is a polymer lithium ion secondary battery using a gel solid electrolyte for a lithium ion battery.

In general, a polymer lithium ion secondary battery has a strip-shaped negative electrode made of a substance capable of doping and undoping lithium ions such as a carbon material, and a lithium ion such as lithium cobalt oxide or lithium nickel oxide. A laminated electrode body in which a strip-shaped positive electrode made of a composite oxide is laminated and a gel electrolyte layer is formed between the negative electrode and the positive electrode is an external output terminal connected to the laminated electrode body. The negative electrode lead and the positive electrode lead are led out to the outside and sealed in a laminate film as an exterior member.

[0005] The polymer lithium ion secondary battery has high safety without fear of liquid leakage. Further, the polymer lithium ion secondary battery does not require an outer can, can be made thinner than before, and has advantages such as flexibility. Thus, polymer lithium ion secondary batteries have attracted much attention as secondary batteries having a high operating voltage and a high energy density.

[0006]

However, in the above-mentioned conventional polymer lithium ion secondary battery, there is a problem in the charge / discharge cycle characteristics of the battery such that an internal short circuit occurs during repeated charge / discharge. This is mainly because lithium ions, which should be doped in the negative electrode, are deposited as metallic lithium on the surface of the negative electrode when the battery is charged, and grow in a dendrite shape particularly at the widthwise and longitudinal ends of the negative electrode. This is because an internal short circuit occurs when the lithium dendrite comes into contact with the positive electrode having the opposite polarity.

In a conventional polymer lithium ion secondary battery, a gel electrolyte layer is formed as a thin film between a negative electrode and a positive electrode, and a separator is not required between the negative electrode and the positive electrode. Therefore, the occurrence of the internal short circuit due to the dendrite growth causes not only a decrease in the charge / discharge cycle characteristics but also a decrease in the yield at the time of manufacturing the battery such that the function of the battery itself is not fulfilled.

Accordingly, the present invention has been proposed in view of such a conventional situation. The present invention suppresses the deposition of metallic lithium on the surface of the negative electrode and prevents internal short circuit of the battery, thereby improving reliability. It is an object of the present invention to provide a high-quality solid electrolyte battery with improved characteristics.

[0009]

A solid electrolyte battery according to the present invention, which achieves the above object, comprises a negative electrode comprising a negative electrode active material layer formed on a strip-shaped negative electrode current collector, and a negative electrode comprising a strip-shaped positive electrode current collector. And a positive electrode having a positive electrode active material layer formed thereon, and a stacked electrode body having a solid electrolyte layer formed between the negative electrode and the positive electrode. In the laminated electrode body, at least the dimension in the width direction of the negative electrode is made larger than the dimension in the width direction of the positive electrode, and both ends of the negative electrode in the width direction protrude from both ends of the positive electrode in the width direction. I have.

[0010] In the laminated electrode body, the length of at least the protruding portion in the width direction of the negative electrode is 0.5 mm.
It is preferable to set the thickness to at least 2 mm.

In the laminated electrode body, the longitudinal dimension of the negative electrode is made larger than the longitudinal dimension of the positive electrode, and both ends of the negative electrode in the longitudinal direction protrude from both longitudinal ends of the positive electrode. It may be.

According to the solid electrolyte battery of the present invention configured as described above, at the time of charging, the lithium ions at the widthwise and longitudinal ends of the positive electrode are well doped to the negative electrode side, Since the amount of lithium ions doped into the negative electrode can be increased, deposition of metallic lithium on the surface of the negative electrode, particularly on the widthwise and longitudinal ends of the negative electrode, is suppressed.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. A polymer lithium ion secondary battery 1 shown as an embodiment of the present invention has a structure shown in FIG.
And a negative electrode lead 3 and a positive electrode lead 4 which are external output terminals connected to the laminated electrode body 2 as shown in FIG.
And the laminated electrode body 2 is sealed in a laminate film 5 as an exterior member.

As shown in FIG. 3, the laminated electrode body 2 is formed by laminating and winding a negative electrode 6 and a positive electrode 7, and a gel electrolyte layer 8 is formed between the negative electrode 6 and the positive electrode 7.

As shown in FIG. 4, the negative electrode 6 is formed by forming a negative electrode active material layer 10 on both surfaces of a negative electrode current collector 9. Negative electrode 6
Has a gel electrolyte layer 8 formed on a surface facing the positive electrode 7. The positive electrode 7 has a positive electrode active material layer 12 formed on both surfaces of a positive electrode current collector 11. The positive electrode 7 has a gel electrolyte layer 8 formed on a surface facing the negative electrode 6. Therefore, the negative electrode 6 and the positive electrode 7 are stacked so that the surfaces on which the gel electrolyte layers 8 are formed face each other.

In the negative electrode 6, as the negative electrode current collector 9,
For example, a metal foil such as a copper foil, a nickel foil, and a stainless steel foil can be used. These metal foils are preferably porous metal foils. By making the metal foil a porous metal foil, the adhesive strength between the current collector and the active material layer can be increased. As such a porous metal foil, in addition to a punching metal and an expanded metal, a metal foil having a large number of openings formed by an etching process can be used.

In order to form the negative electrode active material layer 10, it is preferable to use a material capable of doping / dedoping lithium as the negative electrode active material. Examples of the material that can be doped / undoped with lithium include graphite, a non-graphitizable carbon-based material, and an easily graphitized carbon-based material.
Specific examples of such carbon materials include pyrolytic carbons, cokes, graphites, glassy carbon fibers, organic polymer compound fired bodies, carbon fibers, and activated carbon. Examples of the coke include pitch coke, needle coke, petroleum coke, and the like. The fired organic polymer compound is obtained by firing a phenol resin, a furan resin or the like at an appropriate temperature and carbonizing the same. Further, as other negative electrode active materials, for example, lithium metal, lithium alloy and the like can be used. For example, a lithium alloy includes Li-Al.

In order to form the negative electrode active material layer 10,
A plurality of these negative electrode active materials may be used together.
When forming the negative electrode active material layer 10, a known conductive agent, a binder (binder), or the like may be included.

To produce the negative electrode 6, first, for example, the above-mentioned negative electrode active material and polyvinylidene fluoride as a binder are mixed, and n-methylpyrrolidone is added as a solvent to form a slurry. Next, this slurry was applied on a copper foil to be the negative electrode current collector 9 using a doctor blade, dried at a high temperature, and the solvent was removed by vaporization to remove the negative electrode 6.
Is produced. Here, the mixing ratio of the negative electrode active material, the binder, and the solvent is not limited as long as the mixture is in the form of a uniformly dispersed slurry.

In the positive electrode 7, as the positive electrode current collector 11, for example, a metal foil such as an aluminum foil, a nickel foil, and a stainless steel foil can be used. These metal foils are preferably porous metal foils. By making the metal foil a porous metal foil, the adhesive strength between the current collector and the active material layer can be increased. As such a porous metal foil, in addition to a punching metal and an expanded metal, a metal foil having a large number of openings formed by an etching process can be used.

In forming the positive electrode active material layer 12, a metal oxide, a metal sulfide, or a specific polymer material can be used as the positive electrode active material depending on the type of the intended battery. As the positive electrode active material, Li _x MO ₂ (M represents one or more transition metals, preferably Co, Ni, or Mn, x varies depending on the charge / discharge state of the battery, and 0.05 ≦ x
≦ 1.10. ) Can be used. As a transition metal constituting the lithium composite oxide, Co, Ni, Mn, or the like is preferable. Specific examples of such a lithium composite oxide include LiCoO ₂ , LiNiO ₂ , and LiNi _y Co _(1-y)
O ₂ (however, 0 <y <1), LiMn ₂ O _{4 and the} like. Further, Co may be replaced with some Al.

In order to form the positive electrode active material layer 12,
A plurality of these positive electrode active materials may be used together.
In forming the positive electrode active material layer 12, a known conductive agent or binder (binder) may be included.

To manufacture the positive electrode 7, for example, the above-described positive electrode active material, a carbon material as a conductive material, polyvinylidene fluoride as a binder, and n as a solvent are mixed.
-Add methylpyrrolidone to make a slurry. next,
This slurry was used for the positive electrode current collector 1 using a doctor blade.
The positive electrode 7 is produced by applying the composition on an aluminum foil to be dried and drying at a high temperature to evaporate and remove the solvent. Here, the mixing ratio of the positive electrode active material, the conductive material, the binder, and the solvent is not limited as long as the mixture is in a uniformly dispersed slurry state.

In order to form the gel electrolyte layer 8, a single or a mixture of two or more solvents such as propylene carbonate, ethylene carbonate, γ-butyl lactone, dimethyl carbonate, and diethyl carbonate are used as the electrolyte. Can be.

The electrolyte contained in the above-mentioned electrolytic solution includes:
For example, LiCl, LiBr, LiClO ₄ , LiP
F ₆ , LiBF ₄ , LiAsF ₆ , LiB (C ₆ H ₅ ) ₄ , L
Lithium salts such as i (CH ₃ SO ₃ ) and LiCF ₃ SO ₃ can be used.

As the polymer material for gelling the electrolyte, for example, polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or the like can be used.

The method for forming the gel electrolyte layer 8 includes a method in which a gel electrolyte previously formed into a thin film is disposed on the negative electrode 6 and the positive electrode 7 and a method in which the surface of the negative electrode 6 and the positive electrode 7 are in a liquid state. There is a method in which a gel electrolyte is provided and formed into a thin film. The thickness of the gel electrolyte layer 8 is 15 μm or more and 60 μm or more.
m or less. The reason why the film thickness is set to 15 μm or more is that an internal short circuit increases when the film thickness is less than 15 μm. The reason why the film thickness is set to 60 μm or less is that if the film thickness is more than 60 μm, the volume energy density becomes disadvantageous in density.

As shown in FIG. 5, when the laminated electrode body 2 is wound, as shown in FIG. 5, both ends 6a of the negative electrode 6 in the width direction protrude from both ends 7a of the positive electrode 7 in the width direction. Have been. In the laminated electrode assembly 2, FIG.
As shown in the figure, when the winding structure is adopted, the innermost winding portion 6b of the negative electrode 6 is located further inside the innermost winding portion 7b of the positive electrode 7, and the innermost winding portion of the negative electrode 6 is formed. The peripheral end 6c on the side of the turning part 6b
Are formed to protrude from a peripheral end portion 7c of the positive electrode 7 on the innermost peripheral winding portion 7b side. When the laminated electrode body 2 has a wound structure, the outermost winding part 7 d of the positive electrode 7 is formed.
The outermost winding part 6d of the negative electrode 6 is located on the outer periphery of the negative electrode 6 further. It has a protruding shape.

Here, as shown in FIG.
Are defined as W ₁ and L _{1 in} the width direction and the length direction, respectively. Similarly, the dimensions of the positive electrode 7 in the width direction and the longitudinal direction are W ₂ and L ₂ , respectively.

In this case, in the laminated electrode body 2, both ends 6 a of the negative electrode 6 in the width direction are larger than both ends 7 a of the positive electrode 7 in the width direction by ΔW. Therefore, ΔW can be obtained as ((W ₁ −W ₂ ) / 2).

Further, in the laminated electrode body 2, the length L ₁ of the negative electrode 6 in the longitudinal direction is larger than the length L ₂ of the positive electrode 7 in the longitudinal direction by (l + m + n). Therefore,
(L + m + n) can be obtained as (L ₁ −L ₂ ). 1 indicates that the innermost winding part 6b of the negative electrode 6 is located further inside the innermost winding part 7b of the positive electrode 7,
Is the length required for the outermost winding part 6d of the negative electrode 6 to be located further outside the outermost winding part 7d. Also,
m and n are the lengths required for the negative electrode 6 to protrude from the positive electrode 7 in the longitudinal direction.

Therefore, when the laminated electrode body 2 has a wound structure as shown in FIG. 5, both ends 6a of the negative electrode 6 in the width direction are ΔW smaller than both ends 7a of the positive electrode 7 in the width direction. Will protrude one by one.

As shown in FIG. 3, when the laminated electrode body 2 has a laminated structure, the peripheral end portion 6c of the negative electrode 6 on the innermost peripheral winding portion 6b side has a distance of m from that of the positive electrode 7. , And the peripheral end 6e of the negative electrode 6 on the outermost winding part 6d side protrudes by n from that of the positive electrode 7. If the length L _{1 of} the negative electrode 6 in the longitudinal direction is larger than the length L ₂ of the positive electrode 7 by l, the peripheral end of the negative electrode 6 on the side of the innermost winding portion 6b Part 6c
In addition, the peripheral end portion 6e on the outermost peripheral winding portion 6d side does not protrude from that of the positive electrode 7, and is wound so as to coincide with each other.

In the laminated electrode assembly 2, in order for the innermost winding portion 6 b of the negative electrode 6 to be located inside the innermost winding portion 7 b of the positive electrode 7, the negative electrode 7 is located inside the negative electrode 7 from the positive electrode 7 side. In the case of winding toward the side 6, the innermost winding part 6b of the negative electrode 6 protrudes by m from that of the positive electrode, and the outermost winding part 6d of the negative electrode 6 is (n + 1) with respect to that of the positive electrode 7. It is wound only after protruding. Conversely, when winding from the negative electrode 6 side to the positive electrode 7 side with the positive electrode 7 inside, the negative electrode 6
The innermost winding part 6b is (m + l ₁ ) with respect to that of the positive electrode.
The outermost winding portion 6d of the negative electrode 6 protrudes only (n + l ₂ ) from that of the positive electrode 7 and is wound. Here, l ₁ is a length required for the outermost winding part 6a of the negative electrode 6 to be located further inside the innermost winding part 7b of the positive electrode 7. Further, l ₂ is a length required for the outermost winding part 6 d of the negative electrode 6 to be located further outer circumference of the outermost winding part 7 d of the positive electrode 7.

In such a laminated electrode body 2, at least the length ΔW of the protruding portion in the width direction of the negative electrode 6.
Is preferably 0.5 mm or more and 2 mm or less.

The length ΔW of the protruding portion is 0.5 mm
The reason for this is that if it is less than the above, dendrite deposition at both end portions 6a in the width direction of the negative electrode 6 increases, and internal short circuit increases. The reason why the length ΔW of the protruding portion is set to 2 mm or less is that the volume energy density decreases when the protruding portion is increased. Since the battery using the gel electrolyte has a thicker electrolyte layer than the battery using the non-aqueous electrolyte, the battery has a larger volume than the battery using the non-aqueous electrolyte, and the volume energy This is because the density decreases. For example, when actually used in mobile phones, etc., at least 200
A volume energy density of Wh / l is required. Therefore, when a gel electrolyte is used, the length of the protruding portion is preferably within 2 mm to satisfy a volume energy density of 200 Wh / l.

In such a laminated electrode body 2, the length m of the protruding portion at the peripheral end portion 6c of the negative electrode 6 on the innermost peripheral winding portion 6b side, and the outermost peripheral winding portion 6d of the negative electrode 6
It is preferable that the length n of the protruding portion at the peripheral end portion 6e on the side is also 0.5 mm or more and 2 mm or less for the above-described reason.

As shown in FIG. 3, in the laminated electrode body 2, for example, when such a winding structure is adopted, the negative electrode active material on the inner peripheral side in the innermost peripheral winding portion 6 b of the negative electrode 6 Tier 1
0a, and the negative electrode active material layer 10b on the outer peripheral side in the outermost peripheral winding portion 6d of the negative electrode 6 need not always be formed. The mixture of the above-described negative electrode active material and the like may not be applied to the portion of the non-contact surface with the positive electrode 7 having the opposite polarity when the negative electrode 6 is manufactured.

As shown in FIG. 7, for example, the negative electrode lead wire 3 is led out from one end 6a in the width direction of the negative electrode 6 to a peripheral end 6c on the innermost winding portion 6b side of the negative electrode 6. It is attached so that. Further, the positive electrode lead wire 4 is attached, for example, to the peripheral end portion 7c of the positive electrode 7 on the innermost winding portion 7b side.
Is attached so as to be led out from one end 7a in the width direction of the first member. The negative electrode lead 3 and the positive electrode lead 4 include
A metal material such as aluminum, copper, nickel, and stainless steel can be used. For example, the metal material is processed into a thin plate or a mesh shape, and is attached to the negative electrode 6 and the positive electrode 7 using a method such as resistance welding or ultrasonic welding. .

In the laminated electrode body 2, both ends 6 a of the negative electrode 6 in the width direction protrude from both ends 7 a of the positive electrode 7 in the width direction. Also,
In the laminated electrode body 2, the gel electrolyte layer 8 is formed as a thin film without disposing a separator between the negative electrode 6 and the positive electrode 7. For this reason, in the laminated electrode body 2, when a lead wire is attached to the electrode, an internal short circuit occurs due to the contact of the lead wire with the electrode of the opposite polarity or the end face of the current collector, as compared with the related art. The problem that it is easy to do it arises.
The occurrence of the internal short circuit causes a significant decrease in the yield during the manufacture of the battery.

Therefore, the negative electrode lead wire 3 and the positive electrode lead wire 4 are provided with an insulating tape 13 made of an insulator at positions corresponding to one end 6a of the negative electrode 6 in the width direction and one end 7a of the positive electrode 7 in the width direction. Is wound. The insulating tape 13 only needs to have an insulating property that does not react with an electrolytic solution or the like, and examples thereof include polyimide and the like. In addition, the negative electrode lead wire 3 and the positive electrode lead wire 4 have a configuration in which the insulating tape 13 is wound. However, the present invention is not limited to such a configuration. For example, an insulating coating made of an insulator is formed on these leads. A configuration may be adopted.

As described above, in the laminated electrode body 2, the insulation between the negative electrode lead wire 3 and the end surface of the positive electrode 7 or the positive electrode current collector 11, and the end surface of the positive electrode lead wire 4 and the negative electrode 6 or the negative electrode current collector 9 , And the defect rate at the time of battery production can be reduced.

In the laminated electrode body 2, the negative electrode lead wire 3 is attached to the peripheral end 6 c of the negative electrode 6 on the innermost winding part 6 b side, and the positive electrode lead wire 4 is attached to the innermost peripheral winding of the positive electrode 7. Although the configuration is such that it is attached to the peripheral end 7c on the turning side 7a, the configuration is not limited to this. In the laminated electrode body 2, the negative electrode lead wire 3 may be attached to the peripheral end 6 e of the negative electrode 6 on the outermost winding part 6 d side, and / or the positive electrode lead wire 4 may be attached to the outermost peripheral winding of the positive electrode 7. Turning part 7d
It may be configured to be attached to the peripheral end 7e on the side.

Further, in the laminated electrode body 2, the negative electrode lead wire 3 and the positive electrode lead wire 4 are attached so as to be led out from the same direction. However, the present invention is not limited to such a structure, and the lead wires are drawn out from different directions. It is good also as a structure attached so that it may be performed.

As shown in FIG. 1, the laminate film 5 is formed of, for example, three layers in which polyethylene terephthalate, aluminum foil, and polyethylene are laminated in this order. The laminated film 5 is formed in a substantially bag shape, for example, by laminating films with the polyethylene side as the inner surface. After storing the laminated electrode body 2, the laminated film 5 is hermetically sealed by heat-sealing a sealing portion 5a serving as a storage port.

According to the polymer lithium ion secondary battery 1 of the present invention configured as described above, the width and length dimensions of the negative electrode 6 are made larger than the width and length dimensions of the positive electrode 7. And the widthwise and longitudinal ends of the negative electrode 6 (in this case,
Both end portions 6a in the width direction, peripheral end portions 6 on the innermost winding portion 6b side
c, the circumferential end 6e on the outermost winding portion 6d side is the widthwise and longitudinal end portion of the positive electrode 7 (in this case, both ends 7a in the width direction and the circumferential end on the innermost winding portion 7b side). Portion 7c, the outer edge 7e) of the outermost winding portion 7d side, the lithium ion at the widthwise and longitudinal ends of the positive electrode 7 during charging is good toward the negative electrode 6 side during charging. And the amount of lithium ions doped into the negative electrode 6 can be increased.
In particular, it is possible to suppress the deposition of metallic lithium at the widthwise and longitudinal ends of the negative electrode 6. Therefore, in the polymer lithium ion secondary battery 1, an internal short circuit can be prevented from occurring, and the charge / discharge cycle characteristics of the battery can be greatly improved, and the defective rate at the time of manufacturing the battery can be reduced.

The polymer lithium ion secondary battery 1
In the above, the laminated electrode body 2 has a wound structure, but is not limited to such a configuration. As shown in FIG. 8, the polymer lithium ion secondary battery 1 may be configured to have the stacked electrode body 14 in a folded structure.

The laminated electrode body 14 is formed, for example, of the negative electrode current collector 1.
5, a negative electrode 17 having a negative electrode active material layer 16 formed on one surface.
And a positive electrode 20 in which a positive electrode active material layer 19 is formed on one surface of a positive electrode current collector 18 is laminated and folded with the negative electrode active material layer 16 side and the positive electrode active material layer 19 side facing each other. A gel electrolyte layer 21 is formed between 17 and the positive electrode 20.

The polymer lithium ion secondary battery 1
In this case, as shown in FIG. 9, a configuration having a stacked electrode body 22 having a stacked structure may be adopted.

The laminated electrode body 22 is made of, for example, the negative electrode current collector 2.
3, a negative electrode 25 having a negative electrode active material layer 24 formed on both surfaces.
And a plurality of positive electrodes 28 each having a positive electrode active material layer 27 formed on both surfaces of a positive electrode current collector 26 are stacked in order, and a gel electrolyte layer 29 is interposed between the stacked negative electrode 25 and positive electrode 28. Be formed.

In the laminated electrode body 22, the negative electrode lead wires 30 attached to the individual negative electrodes 25 are connected to the external output negative terminal 31 and the positive electrode leads 30 attached to the individual positive electrodes 28, respectively. Line 32
Are connected to a positive terminal 33 for external output. The laminated electrode body 22 is enclosed in a laminate film (not shown) while leading the negative electrode terminal 31 and the positive electrode terminal 33 to the outside.

In the case where the laminated electrode body 22 has such a stacked structure, the laminated electrode body 2
It is not always necessary to form the negative electrode active material layer 24a on the upper surface and the negative electrode active material layer 24b on the lower surface. When the negative electrode 25 is manufactured, a mixture of the above-described negative electrode active material and the like may not be applied to a portion that is not a contact surface with the positive electrode 7 having the opposite polarity.

[0053]

EXAMPLES Hereinafter, examples in which a nonaqueous electrolyte secondary battery according to the present invention is actually manufactured will be described. Further, a comparative example manufactured for comparison with these examples will be described.

Example 1 In Example 1, in order to produce a negative electrode, first, 91% by weight of graphite and 9% by weight of polyvinylidene fluoride were mixed, and n-methylpyrrolidone was added to the mixture in an amount of 1: 1.
Add 1 times the amount to make a slurry. Next, the slurry was uniformly applied to one side of a copper foil using a doctor blade, dried at a high temperature, and n-methylpyrrolidone was vaporized and removed to prepare a negative electrode coated foil. Next, the negative electrode-coated foil was compression-molded by applying an appropriate pressure using a roller press machine, and cut into a length of 370 mm and a width of 51 mm to produce a strip-shaped negative electrode.

To produce a positive electrode, first, LiCoO ₂
, 91% by weight of graphite, 3% by weight of polyvinylidene fluoride, and 0.6 times the amount of n-methylpyrrolidone based on the mixture to form a slurry. Next, the slurry was uniformly applied to one side of an aluminum foil using a doctor blade, and then dried at a high temperature.
-Methylpyrrolidone was vaporized and removed to prepare a positive electrode coating foil. Next, the positive electrode coating foil was compression-molded by applying an appropriate pressure using a roller press, and the length of the foil was adjusted to 30 mm.
It was cut to 0 mm and 50 mm in width to produce a belt-shaped positive electrode.

A negative electrode lead wire made of mesh copper was spot-welded to the negative electrode, and a positive electrode lead wire made of mesh aluminum was spot-welded to the positive electrode, and these were used as external output terminals.

To form the gel electrolyte layer, first, 7.2% by weight of polyvinylidene fluoride, 13.3% by weight of ethylene carbonate, and 4.13% by weight of propylene carbonate.
8% by weight, 13.9% by weight of γ-butyl lactone, 57.1% by weight of dimethyl carbonate, and 3.7% by weight of LiPF ₆ were mixed. Dimethyl carbonate is used as a solvent for dissolving polyvinylidene fluoride. Next, this mixed solvent is applied in a liquid state to the electrode surface using a doctor blade, dried in a constant temperature bath at 70 ° C. for 3 minutes, and dimethyl carbonate is vaporized and removed, whereby the gel electrolyte layer is formed into a thin film. Molded.

The negative electrode and the positive electrode produced as described above were
The interval is set to 50 μm, and the width and longitudinal dimensions of the negative electrode are made larger than those of the positive electrode 7 in the width direction and the longitudinal direction. The laminate was wound and wound so as to have a shape protruding from the end in the longitudinal direction, thereby producing a laminated electrode body.

In this case, both ends of the negative electrode in the width direction protrude by 0.5 mm from both ends of the positive electrode in the width direction. In addition, both ends of the negative electrode in the longitudinal direction protrude by 0.5 mm from both ends of the positive electrode in the longitudinal direction. In addition, the size of the laminated electrode body is 36 mm × 51 mm × 5 mm.

The laminated electrode assembly thus manufactured was put out to a thickness of 1 while leading the negative electrode lead and the positive electrode lead to the outside.
It was sealed in a laminate film of 50 μm to produce a polymer lithium ion secondary battery.

Example 2 In Example 2, a polymer lithium ion secondary battery was produced in the same manner as in Example 1, except that the negative electrode was cut into a length of 370 mm and a width of 52 mm.

In this case, both ends in the width direction of the negative electrode protrude by 1.0 mm from both ends in the width direction of the positive electrode.

Example 3 In Example 3, a polymer lithium ion secondary battery was produced in the same manner as in Example 1, except that the negative electrode was cut into a length of 370 mm and a width of 53 mm.

In this case, both ends of the negative electrode in the width direction protrude by 1.5 mm from both ends of the positive electrode in the width direction.

Example 4 In Example 4, a polymer lithium ion secondary battery was produced in the same manner as in Example 1, except that the negative electrode was cut into a length of 370 mm and a width of 54 mm.

In this case, both ends in the width direction of the negative electrode protrude by 2.0 mm from both ends in the width direction of the positive electrode.

Comparative Example 1 In Comparative Example 1, a polymer lithium ion secondary battery was manufactured in the same manner as in Example 1 except that the negative electrode was cut into a length of 370 mm and a width of 50 mm.

In this case, both ends in the width direction of the negative electrode do not protrude from both ends in the width direction of the positive electrode, and have a shape which matches each other.

Comparative Example 2 In Comparative Example 2, a polymer lithium ion secondary battery was produced in the same manner as in Example 1, except that the negative electrode was cut into a length of 370 mm and a width of 55 mm.

In this case, both ends in the width direction of the negative electrode protrude by 2.5 mm from both ends in the width direction of the positive electrode.

Comparative Example 3 In Comparative Example 3, a polymer lithium ion secondary battery was produced in the same manner as in Example 1 except that the negative electrode was cut into a length of 370 mm and a width of 56 mm.

In this case, both ends of the negative electrode in the width direction protrude from the both ends of the positive electrode in the width direction by 3.0 mm.

Characteristics Evaluation Test Twenty polymer lithium ion secondary batteries of Example 2 and Comparative Example 1 produced as described above were each produced, and the current was 190 mA and the upper limit voltage was 4.2 V.
Charge, followed by a discharge cut-off voltage of 3.0 with a load of 16Ω.
Perform 30 charge / discharge cycles to discharge to V,
After charging under the above conditions again, the battery was left at room temperature for 10 days. As a result, a secondary battery whose circuit voltage was reduced to 3.9 V or less was measured as an internal short-circuit product, and the yield was determined from the number of occurrences of the internal short-circuit product.

The charging and discharging of the polymer lithium ion secondary batteries of Example 2 and Comparative Example 1 were repeated, and the discharge capacity of each cycle was measured. From this discharge capacity for each cycle, the capacity retention ratio with respect to the discharge capacity in the second cycle was determined.

The results of these evaluations are shown in Table 1 and FIG.

[0076]

[Table 1]

As shown in Table 1, since the number of the internal short-circuited products of Example 1 was smaller than that of the internal short-circuited products of Comparative Example 1, the yield at the time of manufacturing the battery was greatly reduced. It turns out that it improved. Also, as shown in FIG.
Since the decrease in the capacity retention rate of Example 2 is more gradual than the decrease in the capacity retention rate of Comparative Example 1, it can be seen that the charge / discharge cycle characteristics have been significantly improved.

From the above, at least the conventional case in which the widthwise and longitudinal ends of the negative electrode do not protrude from the widthwise and longitudinal ends of the positive electrode and are identical to each other is considered. It can be seen that in the case where both ends in the width direction of the negative electrode are formed to protrude from both ends in the width direction of the positive electrode, deposition of metallic lithium at the end of the negative electrode is suppressed, and occurrence of an internal short circuit can be prevented. Therefore, in order to prevent the occurrence of an internal short circuit, it is preferable that the length of at least these protruding portions be 0.5 mm or more.

Next, the volume energy densities of the polymer lithium ion secondary batteries of Examples 1 to 4 and Comparative Examples 1 to 3 were measured.

FIG. 11 shows the evaluation results.

As is apparent from FIG. 11, in Examples 1 to 4 and Comparative Examples 1 to 3, the volume energy density decreases as the length of the protruding portion increases. . Therefore, in order to satisfy the volume energy density of 200 Wh / l as described above, it is preferable that at least the length of the protruding portion is 2 mm or less.

From the above, at least the length of the protruding portion in the width direction of the negative electrode is 0.5 mm or more and 2 mm or more.
It has become clear that the following is preferred.

[0083]

As described in detail above, according to the solid electrolyte battery of the present invention, at least the dimension in the width direction of the negative electrode is made larger than the dimension in the width direction of the positive electrode, and the width in the width direction of the negative electrode is reduced. Since both ends are shaped to protrude from both ends in the width direction of the positive electrode, lithium ions at the ends in the width direction and the longitudinal direction of the positive electrode during charging will be well doped to the negative electrode side, Since the amount of lithium ions doped into the anode can be increased, the deposition of metallic lithium on the surface of the negative electrode, particularly on the width and longitudinal ends of the negative electrode, is suppressed, and the occurrence of an internal short circuit in the battery is prevented. Can be. Therefore, according to the solid electrolyte battery of the present invention, the charge / discharge cycle characteristics of the battery can be significantly improved, and the defect rate during battery fabrication can be reduced, and a high quality solid electrolyte battery with improved reliability Can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a configuration of a polymer lithium ion secondary battery shown as an embodiment of the present invention.

FIG. 2 is a perspective view showing a laminated electrode body of the polymer lithium ion secondary battery.

FIG. 3 is a cross-sectional view illustrating a laminated electrode body of the polymer lithium ion secondary battery.

FIG. 4 is an enlarged cross-sectional view of a main part illustrating a laminated electrode body of the polymer lithium ion secondary battery.

FIG. 5 is a diagram illustrating a laminated electrode body of the polymer lithium ion secondary battery viewed from the direction A in FIG. 3;

FIG. 6 is a plan view illustrating a configuration of a laminated electrode body in the polymer lithium ion secondary battery.

FIG. 7 is a plan view illustrating a lead wire connected to the laminated electrode body of the polymer lithium ion secondary battery.

FIG. 8 is a cross-sectional view illustrating a folded structure of the laminated electrode body in the polymer lithium ion secondary battery.

FIG. 9 is a cross-sectional view illustrating a stacked structure of a stacked electrode body in the polymer lithium ion secondary battery.

FIG. 10 is a characteristic diagram showing the relationship between the number of charge / discharge cycles and the capacity retention ratio in Example 2 and Comparative Example 1.

FIG. 11 is a characteristic diagram showing the relationship between the length of the protruding portion and the volume energy density in Examples 1 to 4 and Comparative Examples 1 to 3.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery, 2 laminated electrode body, 3 negative electrode lead wire, 4 positive electrode lead wire, 5 laminated film, 6 negative electrode, 6a
b Innermost winding part of negative electrode, 6c Peripheral end of innermost winding part side of negative electrode, 6d Outermost peripheral part of negative electrode, 6e Peripheral end part of outermost winding part of negative electrode, 7 positive electrode 7a, both ends in the width direction of the positive electrode, 7b the innermost winding part of the positive electrode, 7c the peripheral end part on the innermost winding part side of the positive electrode, 7d the outermost winding part of the positive electrode,
7e Peripheral end on the outermost winding part side of positive electrode, 8 Gel electrolyte layer, 13 Insulating tape

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masashi Shibuya 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Satoshi Goto 7-35, Kita-Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation F-term (reference) 5H014 AA01 BB01 BB04 BB05 BB06 BB08 CC01 CC07 EE02 EE05 EE07 EE10 HH06 5H022 AA09 AA18 BB01 BB11 BB25 CC11 CC19 5H029 AJ05 AJ05 AK03 AL01 AM01 AL02 AM06 AM16 BJ04 BJ06 BJ12 BJ14 BJ15 CJ02 CJ03 CJ04 CJ05 CJ06 CJ07 CJ08 CJ12 CJ22 EJ01 EJ03 EJ12 HJ04

Claims (4)

[Claims] 1. A negative electrode having a negative electrode active material layer formed on a strip-shaped negative electrode current collector and a positive electrode having a positive electrode active material layer formed on a strip-shaped positive electrode current collector are laminated. And a solid electrolyte layer having a solid electrolyte layer formed between the positive electrode and the positive electrode. In the solid electrolyte battery, at least the width of the negative electrode is greater than the width of the positive electrode. A solid electrolyte battery characterized in that it is made large and both ends in the width direction of the negative electrode protrude from both ends in the width direction of the positive electrode. 2. In the laminated electrode body, the length of the protruding portion in the width direction of the negative electrode is at least 0.5.
2. The solid electrolyte battery according to claim 1, wherein the thickness is not less than 2 mm and not more than 2 mm. 3. In the laminated electrode body, the longitudinal dimension of the negative electrode is made larger than the longitudinal dimension of the positive electrode, and both ends of the negative electrode in the longitudinal direction are both longitudinal ends of the positive electrode. 2. The solid electrolyte battery according to claim 1, wherein the solid electrolyte battery protrudes from a portion. 4. In the laminated electrode body, a lead wire is attached to each of the negative electrode and the positive electrode, and an insulating material is provided at a position corresponding to a widthwise end of the lead wire on the negative electrode and the positive electrode. 2. The fixed electrolyte battery according to claim 1, further comprising means.