JP3198931B2 - Flat battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in liquid leakage resistance of a flat type battery.

[0002]

2. Description of the Related Art A flat battery having a general configuration is described.
This will be described with reference to FIG.

In FIG. 3 , 1 is a sealing plate also serving as a negative electrode terminal, 2 is a positive electrode case also serving as a positive electrode terminal, 3 is a gasket made of synthetic resin, 4 is a separator made of polypropylene non-woven fabric or glass fiber, and 5 is a transition metal. Oxide,
Positive electrode formed by adding conductive agent and binder to sulfide, 6
Is a negative electrode of lithium metal, lithium aluminum alloy or the like.

The battery is assembled by filling a negative electrode 6, a separator 4, a positive electrode 5 and an electrolyte into the battery, and opening the opening of the positive electrode case 2 between the positive electrode case 2 and the sealing plate 1 via an insulating gasket 3. It is performed by caulking inside and closing.

However, in such a conventional example, the contact area between the positive electrode case 2 and the gasket 3 is reduced due to the hermetic sealing of the battery. This is for the following reason.

That is, when the bottom portion of the gasket is compressed by the sealing, the compressed portion moves substantially uniformly toward the center and the outer periphery of the battery. However, as a matter of course, the diameter is larger in the outer peripheral direction than in the central direction of the battery. Moving. Further, the outer diameter of the positive electrode case 2 is increased by the sealing. For these reasons, the contact area between the positive electrode case 2 and the gasket 3 decreases, and the sealing performance between the positive electrode case 2 and the gasket 3 decreases.

[0007]

In general, battery leakage causes a decrease in battery performance due to a decrease in electrolyte and causes corrosion damage to equipment using the battery. For this reason, high reliability is required for the liquid leakage resistance of the battery.

[0008] Battery leakage occurs between the sealing plate and the gasket and between the positive electrode case and the gasket, but the latter is generally more likely to occur. This is because the gasket is in good contact with the gasket between the sealing plate and the gasket at the opening of the gasket and the folded end of the peripheral edge of the gasket, that is, at the shoulder of the gasket. This is because they are in contact with each other, and a slight gap is easily generated. Therefore, it is necessary to increase the contact area between the positive electrode case and the gasket.

However, the components of the battery require a certain amount of clearance between each component in order to facilitate assembly, and therefore, after sealing, the contact between the positive electrode case and the gasket is only at the shoulder and the bottom, and There are many non-contact parts between the case and the gasket.

An object of the present invention is to improve the leakage resistance by further increasing the contact area between the positive electrode case and the gasket.

[0011]

In the flat battery according to the present invention, an annular projection protruding toward the bottom of the gasket is formed on the periphery of the flat portion of the cathode case where the inner bottom of the cathode case is in contact with the bottom of the gasket. It is sealed and assembled using a positive electrode case provided with stripes.

A positive case provided with an annular protruding portion protruding toward the gasket bottom at a peripheral portion of a flat portion of the positive case where the inner bottom portion of the positive case is in contact with the gasket bottom; Are assembled by using a gasket provided with an annular groove into which is fitted.

According to the above means, the contact area between the positive electrode case and the gasket can be increased. Thereby, the sealing performance between the positive electrode case and the gasket is enhanced, and a flat battery having excellent liquid leakage resistance is obtained.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
A flat battery that is filled with a power generation element consisting of a negative electrode, a separator, a positive electrode, and an electrolyte inside the battery, and is hermetically assembled with a gasket interposed as an insulator between a sealing plate also serving as a negative electrode terminal and a positive electrode case also serving as a positive electrode terminal. Oh, the positive electrode
Case, the peripheral portion of the flat <br/> Tan portion inner bottom portion of that and the gasket bottom that in contact, has a projecting strip of the annular projecting toward the gasket bottom, also the gasket, the protruding of the annular
The bottom has an annular groove into which the strip fits.
They are sealed together. Then, it is possible to annular projecting strip is to increase the contact area between the positive electrode case and the gasket by being fitted into the groove of the gasket, improving the sealing performance between the positive electrode case and the gasket.

Furthermore , the contact surface between the positive electrode case and the gasket is increased, and a flat battery with less liquid leakage can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the conventional example shown in FIG. 3 are denoted by the same reference numerals.

FIG. 1 shows a coin-type lithium secondary battery used in an embodiment of the present invention. In FIG. 1, a positive electrode 5 is formed by mixing a vanadium pentoxide with a conductive agent such as graphite and a binder and then press-molding, and is connected to a positive electrode case 2 also serving as a positive electrode terminal. The negative electrode 6 is made of a lithium aluminum alloy, and is connected to the sealing plate 1 also serving as a negative electrode terminal.

The positive electrode 5 and the negative electrode 6 were assembled via a separator 4 impregnated with a non-aqueous electrolyte, and sealed with a gasket 3 made of resin to obtain a coin-type completed battery. The non-aqueous electrolyte battery used was one in which lithium perchlorate was dissolved at a ratio of 1 mol / liter in a solvent in which propylene carbonate and dimethoxyethane were mixed at a volume ratio of 1: 1.

An annular protruding line 7 is provided at the peripheral portion of the flat portion 2a of the positive electrode case 2 where the inner bottom portion of the positive electrode case 2 and the gasket bottom portion 3a are in contact with each other, protruding toward the gasket bottom portion 3a. A battery in which the protrusion 7 is in contact with the gasket bottom 3a so as to bite is referred to as a battery A.

Further, as another embodiment of the present invention, the battery shown in FIG. That is, the battery B is the same as the battery A in that the annular protrusion 7 is provided on the peripheral portion of the flat portion 2a of the positive electrode case 2, but the annular groove 8 in which the annular protrusion 7 fits is formed in the gasket bottom. 3a.

For comparison with the batteries A and B according to the embodiment of the present invention, a conventional battery having no annular protrusion shown in FIG.

Each battery has a diameter of 9.0 mm, a thickness of 2.0 mm, and a capacity of about 4 mA in a range of 2 V to 1 V.
h, the following test was performed.

First, the three types of batteries A, B,
Each of 20 batteries C is left in a high-temperature bath at 65 ° C. for 1 hour.
After one hour, the batteries A, B, and C are taken out, and then left in a low-temperature bath at -15 ° C for one hour. This operation is defined as one cycle, and the cycle is repeated. The liquid leakage state of the battery was checked with a microscope of 20 times every 100 cycles, and this operation was continued until the number of cycles reached 1,000.

The results are shown in Table 1.

[0025]

[Table 1]

In the battery C, a leaking battery was detected from 600 cycles, and after 1000 cycles, 4 out of 20 batteries (20%) leaked.

On the other hand, in the batteries A and B according to the embodiments of the present invention, even after repeating 1000 cycles, the leakage of the batteries was 0 out of 20 each. This is because the contact area between the positive electrode case and the gasket is increased by changing the structure of the battery to A or B, whereby the sealing property between the positive electrode case and the gasket is increased, and a flat battery excellent in liquid leakage resistance is obtained. It shows that it can be obtained.

In this embodiment, a lithium-aluminum alloy was used for the negative electrode of the coin-type lithium secondary battery. Instead of the lithium-aluminum alloy, a metal oxide such as lithium titanium oxide or niobium pentoxide, or a natural oxide was used. Carbon such as graphite, artificial graphite and carbon fiber may be used.

Although vanadium pentoxide is used as the positive electrode, lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide may be used instead of vanadium pentoxide.

Further, besides the electrolyte used in the embodiment, for example, LiN (CF3SO2) 2, LiPF6, Li
One or more of the electrolytes such as BF4, LiCF3SO3 and the like may be used as 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, ethylmethyl carbonate, dimethyl carbonate. An organic electrolyte dissolved in a single solvent such as propylene carbonate, γ-butyrolactone, ethylene carbonate, or a mixture of two or more solvents may be used. Further, in this embodiment, the coin-type lithium secondary battery has been described, but the present invention is also applicable to a coin-type lithium primary battery, a button-type alkaline primary battery, an alkaline secondary battery, and the like.

[0031]

As is apparent from the above description, according to the present invention, the annular portion protruding toward the bottom of the gasket is formed on the peripheral portion of the flat portion of the positive case where the inner bottom of the positive case is in contact with the bottom of the gasket. The use of a positive electrode case with a protruding strip ensures long-term leakage resistance,
A highly reliable flat battery can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a battery A according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the battery B;

FIG. 3 is a sectional view of a main part of a battery C in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sealing plate 2 Positive electrode case 2a Flat part 3 Gasket 3a Gasket bottom 4 Separator 5 Positive electrode 6 Negative electrode 7 Annular protrusion 8 Annular groove

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-59830 (JP, A) JP-A-56-67658 (JP, U) JP-A-55-68269 (JP, U) JP-A-54-68269 104930 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 2/02-2/08

Claims (1)

(57) [Claims] 1. A power generation element comprising a negative electrode, a separator, a positive electrode and an electrolyte is filled in a battery, and hermetically assembled with a gasket interposed as an insulator between a sealing plate also serving as a negative electrode terminal and a positive electrode case also serving as a positive electrode terminal. in flat type batteries, the positive electrode case, the inner bottom portion and the peripheral portion of the Tan Taira portion gasket bottom that in contact of its, has a projecting strip of the annular projecting toward the gasket bottom, said gasket
Has an annular groove at the bottom into which the annular protrusion is fitted.
A flat-type battery.