JPH0567457A - Nonaqueous high capacity secondary battery - Google Patents

Abstract

PURPOSE:To make high capacity by using stainless steel for can material and specifying the range of the external diameter ratio of the top part and the bottom part of a can. CONSTITUTION:A battery can is made of stainless steel, preferably an austenitic- type one and further preferably 304-and 305-type and among them 305-type is most preferable. The thickness of the side of the can is 0.21-0.30mm in the case of a cylindrical type and 0.30-0.40mm in the case of a long ring type and in the case that the length of the can in 50mm or more, the thickness of the can's side is needed to be uniform. The ratio of the top part of the can to the diameter of the bottom part of the can is set to be within 0.995-1.00, preferably 0.997-1.00. As a result, the battery is made high in capacity.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-aqueous secondary battery. More specifically, the present invention relates to a non-aqueous high capacity secondary battery.

[0002]

2. Description of the Related Art Rechargeable batteries such as lead storage batteries and nickel-cadmium batteries have been used as secondary batteries, but in recent years, mobile communication devices, notebook computers, palmtop computers, integrated video cameras, portable CD players. ,
In order to reduce the size and weight of electronic devices such as headphone stereos and cordless phones, there is a demand for higher capacity secondary batteries as power sources for these electronic devices.

A non-aqueous secondary battery using a carbonaceous material capable of doping and dedoping lithium ions (see, for example, JP-A-62-62).
-90863 gazette) is remarkably superior to a secondary battery using a lithium metal or an alloy thereof for a negative electrode in terms of safety, and it is noted that a high energy density can be obtained.

The non-aqueous secondary battery has a voltage of 1.2 V as compared with a nickel-cadmium battery as a secondary battery or a nickel-hydrogen storage alloy battery currently on the market.
Light weight and high capacity, and average voltage is 3.5-3.6V
Since it is high, there is also an advantage that it is only necessary to connect a series of 2 to 3 to a power supply which requires a series connection of 5 to 8 1.2V cells. However, in order to apply to these power sources, if it is matched with the diameter of a conventional battery, a cylindrical can having a long body or an elliptical can having the same minor diameter is used.

Further, over-discharge (state in which voltage becomes close to 0 V)
Even if it becomes, stainless steel cans are used to prevent corrosion of the cans, but when the transfer molding is performed as it is in the conventional case, the diameter of the upper end of the can is reduced if the body is long and the thickness of the can side is made thin to increase the capacity. As a result of being smaller than the diameter of the bottom of the can, there is a disadvantage that the expected high capacity cannot be achieved in correspondence with the reduction in wall thickness.

[0006]

An object of the present invention is to increase the capacity of a non-aqueous secondary battery using a carbonaceous material that can be doped and dedoped with lithium ions.

[0007]

That is, the present invention provides a non-aqueous secondary battery using, as a negative electrode active material, a carbonaceous material that can be doped with lithium ions and dedoped.
A cylindrical or elliptical non-aqueous high material, characterized in that the battery can material is stainless steel, and the ratio of the can outer diameter to the can bottom outer diameter is in the range of 1.00 to 0.995. It is a secondary battery with a capacity.

A detailed description will be given below. The positive electrode active material of the non-aqueous secondary battery of the present invention may be any one that can dedoped and doped with lithium ions. For example, lithium cobalt oxide: Li _X Co _Y M _Z O ₂ (wherein M represents at least one metal selected from Al, In and Sn, and X, Y and Z are each 0 <X ≦.
1.1, 0.5 <Y ≦ 1, Z ≦ 0.1. ) Li _X CoO ₂ (0 <X ≦ 1), Li _X Co _Y Ni _Z O ₂ (0 <X ≦ 1, Y + Z = 1)

Lithium nickel oxides such as Li _X NiO ₂ (0 <X ≦ 1), lithium manganese oxides such as Li _X MnO ₂ , Li _X Mn ₂ O ₄ (0 <X ≦ 1), LiCo _X Mn _{2 -X} O ₄ (0 <X ≦ 0.5) Lithium chrome oxide such as Li _X Cr ₃ O ₈ (0 <X ≦ 1), LiCrO ₂

Lithium vanadium oxides such as Li _X V ₂ O ₅ (0 <X ≦ 1), Li _X V ₆ O ₁₃ , Li _{1 + X} V ₃ O ₈ lithium molybdenum oxides such as Li _X MoO ₃ lithium molybdenum Disulfides, such as Li _X MoS ₂

There are lithium titanium oxides such as Li _x Ti ₂ O ₄ lithium titanium sulfides such as Li _x Ti ₂ S ₂ . Lithium cobalt oxide and lithium manganese oxide are preferable, and lithium cobalt oxide is more preferable.

The film thickness of the positive electrode active material and the binder adhered to the metal foil as the current collector is 30 to 30 per side.
It is 0 μm, preferably 70 to 130 μm. As the metal foil, aluminum, nickel, stainless steel or the like having a thickness of 50 μm to 1 μm can be used.
Aluminum is preferably used, and the thickness thereof is 30 to 8 μm, more preferably 15 to 10 μm.

The carbonaceous material as the negative electrode active material of the non-aqueous secondary battery of the present invention is not particularly limited as long as it can be doped with lithium ions and dedoped. For example, graphite, pyrolytic carbon, pitch. Coke, needle coke, petroleum coke, organic polymer fired bodies (phenol resin, furan resin, polyacrylonitrile, etc.) can be used.

A metal foil as a collector has a thickness of 50 μm.
Copper, nickel, stainless steel or the like having a thickness of m to 1 μm is used. Copper and stainless steel are preferable, and those having a thickness of 30 to 6 μm, and more preferably 12 to 8 μm are used.

The thickness of the active material and the binder adhered to the metal foil is 60 to 750 μm on one side, preferably 140.
Is 400 μm. A cylindrical wound material obtained by winding a metal foil having an active material and a binder adhered to one or both surfaces thereof through a separator is inserted into a battery can of the present invention,
Attach the lead tab, impregnate with a non-aqueous electrolyte solution, and seal.

The non-aqueous electrolyte solution used in the present invention includes, for example, LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiB as the electrolyte.
F ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃
Any one or two of lithium salts such as SO ₂ ) ₂ NLi
A mixture of two or more species can be used.

As the solvent of the electrolytic solution, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, 1,2-
Dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, sulfolane, methylsulfolane, acetonitrile, propionitrile,
Any one kind or a mixture of two or more kinds such as methyl formate, ethyl formate, methyl acetate and ethyl acetate can be used.

As the separator used in the present invention, a single microporous film of polyolefin such as polyethylene or polypropylene, or a single or two or more laminated films thereof can be used. Further, non-woven fabrics such as polyolefin, polyester, polyamide, and cellulose can be used alone or in combination with the above-mentioned porous membrane.

The battery can used in the present invention is made of stainless steel, and an austenite type is preferable for processing a thin long can. More preferably 304
System, 305 system, and most preferably 305 system.

In the case of the cylindrical type, the outer diameter is about 10 to 24 mm,
Can side thickness 0.21 to 0.35 mm, can height 30 to 90 mm
In the case of the oval type, the minor axis is 10 to 24 mm, the can side thickness is 0.30 to 0.45 mm, and the can height is 30 to 70 mm. The effect of the present invention is particularly remarkable in that the can side thickness is cylindrical type 0.21 to 0.30 mm, oval type 0.30 to 0.40 m.
m, can height 50 mm or more.

In the battery can of the present invention, for example, a single drawing is repeated 6 to 12 times, or an annealing jig is attached to the final stage when it is manufactured by a continuous transfer drawing of 6 to 10 steps, and is slowly cooled to room temperature. Alternatively, adjust the punch and die size of the final stage in anticipation of shrinkage.

The thickness of the can side is cylindrical type 0.21 to 0.30 m.
m, oval type 0.30 to 0.40 mm, and can length 50 mm or more, it is necessary to make the can side thickness as uniform as possible. The ratio of the diameter of the top of the can to the diameter of the bottom of the battery can is 1.00
˜0.995, preferably 1.00 to 0.997. As a result, it is possible to achieve a high capacity corresponding to the reduction in the thickness of the non-aqueous secondary battery on the can side.

[0023]

EXAMPLES Next, the present invention will be described in more detail by way of examples and comparative examples other than the present invention, but these do not limit the scope of the present invention.

Example 1 A positive electrode was made into a dispersion by adding a 4% fluororubber ethyl acetate / ethyl cellulose solution to a compound prepared by adding 5% of a carbon-based conductive additive to LiCoSn _0.02 O _{2 as} an active material. Then, this is applied on both sides of an aluminum foil having a thickness of 15 μm, dried, and compressed and pressed.

The film thickness of the fluorocarbon rubber as the active material and the binder is 105 μm per side. This coated film (A) is sized to a width of 74.0 mm. For the negative electrode, a pitch coke having an average particle diameter of 9 μm as an active material was added with an equal amount of an aqueous solution of carboxymethyl cellulose 1 and styrene-butadiene rubber latex particles 2.5 to prepare a dispersion liquid, which was a copper foil having a thickness of 10 μm. Both sides are coated, dried and compressed and pressed.

The thickness of the active material and carboxymethyl cellulose serving as a binder and styrene-butadiene rubber is 265 μm on each side. This coated film (B) is sized to a width of 74.1 mm. After attaching lead tabs to these positive and negative electrodes, the thickness was 34 μm and the width was 7 μm.
It is wound in a spiral shape through an 8 mm polyethylene microporous membrane separator, and the wound product is made of stainless steel 305.
Insert it into a cylindrical can. The cylindrical can has a thickness of 0.22 m on the can side.
m, can height 83.5 mm, can bottom outer diameter 16.23 mm,
The outer diameter of the upper end of the can is 16.22 mm.

After attaching the positive and negative electrode tabs, 7 g of a 3-component mixed solution of propylene carbonate / ethylene carbonate / γ-butyrolactone (1 mol of LiBF ₄₎ was vacuum-impregnated as an electrolyte solution and sealed. The battery is
A cycle in which a constant current of 1.1 amps is charged, the voltage reaches 4.2 V, charging is continued for 5 hours under a constant voltage of 4.2 V, and one hour later, a constant current of 0.55 amperes is discharged to 2.7 V. Repeat. This charge / discharge cycle is performed twice,
The discharge capacity of the third time was measured, and the results are shown in Table 1.

[0027]

[Example 2] The coating film (A) of Example 1 was used as a positive electrode with a width of 6
What was sized to 0.0 mm was used, and as the negative electrode, the coating film (B) of Example 1 was sized to have a width of 60.1 mm. After attaching lead tabs to these positive and negative electrodes, they are spirally wound through a microporous polyethylene separator having a thickness of 35 μm and a width of 63.50 mm to form a hollow wound product. Press this roll into an oval,
Insert into a stainless steel 304 oval can.

The oval can has a can side thickness of 0.40 mm, a can height of 65.5 mm, a can bottom part minor diameter outer diameter 14.03 mm, a can top end minor diameter outer diameter of 14.00 mm, and a can bottom part. The outer diameter of the major axis is 41.1 mm. After attaching the positive and negative electrode tabs, 15.3 g of a three-component mixed solution of 1 mole of LiBF ₄ propylene carbonate / ethylene carbonate / γ-butyrolactone was vacuum-impregnated as an electrolyte solution and sealed.

The battery was charged with a constant current of 2.8 amps, and after the voltage reached 4.2V, the battery was continuously charged under a constant voltage of 4.2V for 5 hours. After 1 hour, a cycle of constant current discharge of 1.4 amp to 2.7 V is repeated. This charge / discharge cycle was performed twice, and the discharge capacity at the third time was measured. The results are shown in Table 1.

[0030]

Comparative Example 1 As a cylindrical can of stainless steel 305, a can side thickness of 0.22 mm, a can height of 83.5 mm, a can bottom outer diameter of 16.23 mm, and a can top outer diameter of 16.12 mm were used. A rolled material is formed so that it can be inserted into the cylindrical can in which the same positive electrode, negative electrode, and separator are wound, and the product is inserted into the cylindrical can. 7 g of the same electrolyte solution as in Example 1 is vacuum impregnated and sealed.

The battery was charged with a constant current of 1.1 amps, and after reaching a voltage of 4.2 V, continued to be charged under a constant voltage of 4.2 V for 5 hours, and one hour later, a constant current of 0.55 amperes was discharged. Is repeated up to 2.7V. This charge / discharge cycle was performed twice, and the discharge capacity at the third time was measured. The results are shown in Table 1.

[0032]

[Comparative Example 2] The oval can of stainless steel 304
Can side thickness 0.40 mm, can height 65.5 mm, can bottom minor axis outer diameter 14.03 mm, can top minor axis outer diameter 13.
92 mm, 41.1 mm long diameter of the bottom of the can was used and wound using the same positive electrode, negative electrode and separator as in Example 2,
Press the roll and insert the largest one that can be inserted into the oval can. 15.3 g of the same electrolyte solution as in Example 2 is vacuum impregnated and sealed.

The battery was charged with a constant current of 2.8 amps, and after the voltage reached 4.2 V, the battery was continuously charged under a constant voltage of 4.2 V for 5 hours. After 1 hour, a cycle of constant current discharge of 1.4 amp to 2.7 V is repeated. This charge / discharge cycle was performed twice, and the discharge capacity at the third time was measured. The results are shown in Table 1.

[0034]

[Table 1]

[0035]

The present invention makes it possible to provide a cylindrical or oval nonaqueous high capacity secondary battery, and its industrial value is great.

Claims (1)

[Claims] 1. A non-aqueous secondary battery using, as a negative electrode active material, a carbonaceous material capable of being doped and dedoped with lithium ions, wherein the battery can material is stainless steel, and the can upper end portion with respect to the can bottom outer diameter. Ratio with outer diameter is 1.00
A cylindrical or oval non-aqueous high-capacity secondary battery characterized by being in the range of 0.995.