JPH10241744A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spiral electrode body, having a noncircular cross section without lowering battery performance by arranging fixing means, for winding up an electrode body on the respective side and upper or lower surfaces parallel to a winding axis of the electrode body, and drilling plural holes on the fixing means. SOLUTION: An electrode body 12, wound into a noncircular cross section, is housed in a battery vessel composed of a metallic laminate sheet. In this battery vessel, the electrode body is fixed by winding a tape, a fixing means 10, e.g. made of polypropylene, so as to cover an electrode end member on the electrode body side surface, in the order of an electrode body side surface 23 parallel to a winding axis, an upper surface 20 of the electrode body, a side surface 21 facing the side surface 23 parallel to the winding axis, a lower surface 22, and the side surface 23. Plural holes 13 are drilled on a portion, positioned on the upper surface 20 of the electrode body of the fixing means 10. Aluminum or its alloy are included as a metal for a metallic laminate sheet. Holes 13 of the fixing means 10 do not hinder the movement of an electrolyte or the gas and may be through-holes or a porous material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or lithium alloy, or a host material containing lithium ions (here, a host material refers to a material that can occlude and release lithium ions). Lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and LiC
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as 10 ₄ or LiPF ₆ is dissolved as an electrolyte.

This non-aqueous electrolyte secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held on a negative electrode current collector as a support, and a reversible electrochemical reaction with lithium ions such as a lithium-cobalt composite oxide. The positive electrode plate, which holds the positive electrode active material that reacts on the positive electrode current collector that is the support, from the separator that holds the electrolytic solution and intervenes between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes Has become.

In the case of a non-cylindrical battery, each of the positive electrode plate and the negative electrode plate is formed into a thin sheet or foil and wound spirally and non-circularly in section through a separator. The outermost circumference of the body is wrapped with tape. (See FIG. 4) The completed electrode body is housed in a battery container made of a metal such as stainless steel, nickel-plated iron, or aluminum. After the electrolyte is injected, the electrode is sealed and fixed with a lid plate. The battery is assembled.

[0005]

However, as described above, some battery containers are made of stainless steel or nickel-plated iron, and have high airtightness and excellent mechanical strength, but have a light weight. There are significant restrictions on the design and design of materials and battery containers.

In order to solve the problem, there has been proposed a method in which an electrode body is housed in a battery container formed of an aluminum laminate sheet.

However, if the conventional non-circular spiral electrode body is housed in a battery container made of an aluminum laminate sheet and the container is hermetically sealed, the winding of the electrode body is loosened and the distance between the electrodes is uneven. , Resulting in a problem of lowering the battery performance.

Therefore, the present invention comprises a spirally wound electrode body having a non-circular cross section and a metal laminate sheet (or film), which do not cause deterioration in battery performance and do not cause complications in the manufacturing process. And a non-aqueous electrolyte secondary battery using the battery container.

[0009]

Therefore, a non-aqueous electrolyte secondary battery according to the first invention is housed in a battery container in which an electrode body wound in a non-circular cross section is formed of a metal laminate sheet. Fixing means for stopping the winding of the electrode body are arranged on the side of the electrode body parallel to the winding axis and on the upper surface and / or lower surface of the electrode body, and the fixing means has a hole. .

According to a second aspect of the present invention, the fixing means is a resin tape having a through-hole formed therein, and the resin tape is parallel to a winding axis on a side surface of the electrode body and on an upper surface of the electrode body. And the lower surface is wound around the electrode body so as to be perpendicular to the winding axis.

The metal of the metal laminate sheet is, in particular, aluminum or an alloy thereof, and other examples include titanium foil. Further, the resin layer and the metal foil layer of the metal laminate sheet are not limited to one layer each, and may be two or more layers.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of a non-aqueous electrolyte secondary battery according to the present invention.

The non-aqueous electrolyte secondary battery 1 according to the present embodiment has an electrode assembly 1 comprising a positive electrode plate, a negative electrode plate, and a separator.
2 is stored in a battery container together with a non-aqueous electrolyte (not shown).

The positive electrode plate has a current collector in which a lithium-cobalt composite oxide is held as an active material. The current collector was obtained by laminating an aluminum foil having a thickness of 4 μm on both sides of a PET film having a thickness of 6 μm and bonding the aluminum foil with an adhesive. The positive electrode plate was prepared by mixing 8 parts of polyvinylidene fluoride as a binder and 5 parts of acetylene black as a conductive agent together with 87 parts of an active material, appropriately adding N-methylpyrrolidone to prepare a paste, and then collecting the paste. It was manufactured by applying and drying both sides of an electric conductor material.

The current collector of the negative electrode plate is a PET having a thickness of 12 μm.
After sputtering copper on both surfaces of the film, the film was obtained by electroplating copper having a thickness of 1 μm.

The negative electrode plate is prepared by mixing 86 parts of graphite (graphite) as a host substance and 14 parts of polyvinylidene fluoride as a binder to prepare a paste on both surfaces of the current collector, and applying and drying the mixture. It was made by doing.

The separator is a polyethylene microporous membrane. The electrolyte was ethylene carbonate: diethyl carbonate = 1: 1 containing 1 mol / l of LiPF _6.
(Volume ratio).

The respective dimensions are such that the positive electrode plate has a thickness of 180 μm.
m, width 29 mm, separator thickness 25 μm, width 33
mm, the negative electrode plate has a thickness of 170 μm and a width of 31 mm. Lead terminals are welded to the positive electrode plate and the negative electrode plate, respectively, and superposed in order. So that it is parallel to the winding axis of
It was spirally wound around it to form an electrode body having a non-circular cross section.
Then, the end portion of the electrode is wound around a length corresponding to the electrode width (the length of the electrode body parallel to the winding axis) with a tape for stopping winding made of polyethylene (here, an adhesive is applied on one side). The electrode body 2 was stuck and fixed to the side wall of the electrode body parallel to the axis. (See FIG. 4) Then, the aluminum laminate film was housed in a battery container 6 formed into a bag shape. Next, the lead terminal was fixed and hermetically sealed, and the electrolyte was sufficiently wetted on each electrode and the separator, and vacuum injection was performed in such an amount that no free electrolyte was present outside the electrode group.

Next, sealing welding is performed to achieve a design capacity of 800 m.
Five batteries (A) of Ah (specification of the conventional battery) were manufactured.

However, the amount of the electrolyte was 4 ml.

As shown in FIG. 2, the airtight battery container 6 has a 12 μm PET film as a surface protective layer 15 on the outermost layer, and a 9 μm aluminum foil as a barrier layer 16 thereunder with a urethane adhesive. Glued. further,
An acid-modified LDP having a thickness of 100 μm
It is made of a laminated film having E (low density polyethylene).

The lead terminals 5 and 5 'are connected from 50 to 1
50 μm acid-modified LDP as an adhesive layer 18 with a metal conductor of 00 μm copper, aluminum, nickel, etc.
E and 70 μm on the outside as an electrolyte barrier layer 19
(A Kuraray ethylene-vinyl alcohol copolymer resin layer is provided. Here, aluminum is used for the positive electrode and copper is used for the negative electrode. However, the structure of the battery container 6 and the leads 5 and 5 ′ Needless to say, drawing out from the battery container is not limited to these.

Next, five comparative batteries (B) were produced in the same manner as described above. However, the polypropylene winding tape 10 is provided with the electrode body side surface 23 parallel to the winding axis, the upper surface 20 of the electrode body, the side surface 21 opposite (opposite to) the electrode body side surface 23 parallel to the winding axis, the lower surface 22 and the side surface. In the order of 23,
The difference is that the electrode body 2 is fixed by being wound so as to cover the electrode terminal portion on the side surface of the electrode body. (See FIG. 3) Next, the battery (C) according to the present invention in the same manner as the comparative battery
Were produced. However, a difference is that a plurality of holes 13 are formed in a portion of the propylene-made winding tape 10 serving as a fixing means, which is located on the upper surface 20 of the electrode body 2.

As the adhesive for the tape, a material obtained by dissolving polyvinylidene fluoride (PVdF) in an NMP solvent was used. Although the adhesive is applied to the entire surface on one side, it is sufficient that the electrode body 2 can be prevented from being wound.

[Test and Results] As a result of measuring the injection time, A was 30 to 35 seconds, B was 90 seconds or more, and C according to the present invention was 25 to 30 seconds, which was inferior to the conventional battery. There was no result.

Next, these batteries A, B and C are left for several hours, and are charged at a constant current of 0.5 C for 3 hours to a constant current and a constant voltage up to 4.1 V to be fully charged, and discharged to 2.75 V. A cycle characteristic test was performed under the condition that the test was performed. FIG. 3 shows the result at this time.

Each value indicates the average value of each battery.

In the conventional battery A, the discharge capacity was lower than that of the batteries B and C, and it could be seen that the number of cycles was increased. A disassembly survey to find out the cause revealed that the winding was loose and gaps were formed between the plates.

Next, when B and C were compared, it was shown that C was superior to B in both discharge capacity and cycle characteristics. As a cause of this, since the electrolytic solution penetrates from the gap between the positive electrode plate on the upper or lower surface of the electrode body and the separator and the negative electrode plate, the battery B in which the gap is closed by the tape as the fixing means is better. It is probable that the electrolyte solution could not penetrate sufficiently and uniformly.

The fixing means in the present invention is not limited to the above-described resin tape, but may be, for example, a resin U-shaped clip for holding the electrode body, and is not limited to this. Examples of the material of the resin tape include polyethylene, polypropylene, polyphenylene sulfide, polyimide, and the like.As the adhesive, an acrylic acid-based or rubber-based conventionally known material can be used, as long as it has an electrolytic solution resistance. .

The fixing means may be provided with a hole so as not to hinder the movement of the electrolyte or gas, and may be a through hole,
It may be a porous material. In particular, it suffices that at least a hole is provided in the electrode end face on the side where the electrolyte is injected.

Further, the non-circular shape is not limited to the shape shown in FIG. 4, but may be, for example, a shape in which opposed straight portions are depressed inward, an elliptical shape, or limited to these. Not even a thing.

[0033]

According to the present invention, a spiral electrode body having a non-circular cross section and a metal laminate sheet (or film) which do not cause a decrease in battery performance and do not cause complication in a manufacturing process are provided. A non-aqueous electrolyte secondary battery using a battery container as a component can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a nonaqueous electrolyte secondary battery according to one embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional explanatory view of a lead terminal of the nonaqueous electrolyte secondary battery according to one embodiment of the present invention.

FIG. 3 is an explanatory diagram of an electrode body according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram of an electrode body.

FIG. 5 is a diagram showing the results of a cycle characteristic test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-aqueous electrolyte secondary battery 5 Positive electrode lead terminal 5 'Negative electrode lead terminal 6 Battery container 10 Fixing means 12 Electrode body 13 Hole 15 Surface protective layer 16 Barrier layer 17 Thermal fusion layer 18 Adhesive layer 19 Electrolyte barrier layer

Claims (2)

[Claims] 1. A non-aqueous electrolyte secondary battery in which an electrode body wound in a non-circular cross section is housed in a battery container made of a metal laminate sheet, wherein the fixing means for stopping the winding of the electrode body is an electrode. A nonaqueous electrolyte secondary battery which is arranged on a side surface of an electrode body parallel to a body winding axis and on an upper surface and / or a lower surface of the electrode body, wherein the fixing means has a hole. 2. The fixing means is a resin tape having a through hole formed therein, and the resin tape is parallel to a winding axis on a side surface of the electrode body and perpendicular to the winding axis on an upper surface and a lower surface of the electrode body. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is wound around an electrode body.