JPH04532Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> This invention relates to an improvement of a board-mounted flat non-aqueous electrolyte battery with lead terminals.

<Prior Art> A battery with lead terminals is a type of non-aqueous electrolyte battery such as a lithium battery that has a particularly high energy density, and the lead terminal can be soldered or screwed to a circuit board of an electronic device. It is used as a memory backup battery, etc.

In conventional non-aqueous electrolyte batteries with lead terminals, the lead terminals are generally joined by spot welding to a predetermined portion of a metal battery case in which a power generating element is housed and assembled as a battery. However, when a lead terminal is spot-welded to the negative terminal plate of a battery case, which has a negative electrode made of a light metal with a low melting point such as lithium or sodium placed in close contact with the inside, the negative electrode partially melts due to the high temperature during welding. However, the molten negative electrode may penetrate through the separator and reach the positive electrode side, causing defects such as leaks and internal short circuits. Therefore, sufficient consideration must be given to the heat generated during welding, especially when spot welding the lead terminal on the negative electrode side.

In order to suppress the adverse effects of heat during spot welding, consideration is first given to reducing the welding current as much as possible to reduce the amount of heat generated. However, care must be taken because reducing the welding current too much may lead to poor welding or insufficient welding strength.

It has also been proposed to make the separator thicker in order to prevent the molten negative electrode from reaching the positive electrode. However, if the separator is made thicker, the internal resistance will increase and the discharge capacity of the battery will also decrease, which is a major disadvantage to battery performance.

Furthermore, a structure has been proposed in which a suitable heat insulating material is applied inside the negative electrode terminal plate so that the heat during spot welding is not transmitted to the ionized interior. However, this not only increases the number of parts and complicates the assembly process, but also reduces the capacity of the power generating element by the volume of the heat insulating material and degrades the discharge performance.

It has also been proposed that instead of spot welding the lead terminal to the battery after assembly, the lead terminal is previously spot welded to the negative terminal plate as a component before the battery is assembled. However, this method has the serious drawback that the assembly of the battery becomes extremely complicated. In other words, the shape of the negative terminal plate to which the lead terminals are bonded is significantly different from that of the negative terminal plate alone, making it impossible to use a normal battery assembly line. As is well known, the negative terminal plate of a flat battery, called a button or coin type, has a circular plate shape, but if a strip-shaped lead terminal is connected to this, it will have a large protrusion as a component. The shape, directionality, and thickness also vary. Therefore, in order to assemble the battery under such conditions, extensive and complicated changes are required. Another problem is that the lead terminals are easily deformed while the negative electrode terminal plate to which the lead terminals are bonded is flowing through the assembly line.

《Problems to be solved by the invention》 This invention was made in view of the above-mentioned problems, and its purpose is to attach the negative electrode made of a light metal such as lithium to the outer surface of the negative terminal plate, which is made of a negative electrode made of a light metal such as lithium. To provide a flat type non-aqueous electrolyte battery with lead terminals having a structure that reduces harmful heat given to the inside of the battery when welding the lead terminals and provides sufficient welding strength.

<Means for Solving the Problems> In order to achieve the above object, this invention provides a non-aqueous electrolyte battery in which a lead terminal is spot-welded to the outer surface of the central part of the negative terminal plate corresponding to the negative electrode. The spot welded portion of the lead terminal is made concave and thinner than the surrounding area, and a reinforcing adhesive is applied to the spot welded portion.

<<Example>> Figs. 1 and 2 show a flat non-aqueous electrolyte battery with lead terminals according to an embodiment of this invention. In this battery, a flat positive electrode can 10 and a dish-shaped negative electrode terminal plate 12 having a smaller diameter are placed facing each other.
A battery case is constructed by sandwiching an annular sealing gasket 14 between the peripheral edges of the two, and the positive electrode mixture 16 housed in the recess of the positive electrode can 10 and the negative electrode terminal plate 1
The negative electrode 20 housed in the recess of the separator 1
A positive electrode mixture 16 and a separator 18 are impregnated with a non-aqueous electrolyte, and are arranged in layers facing each other with 8 interposed therebetween.

The positive electrode can 10 and the negative electrode terminal plate 12 are made of metal plates such as stainless steel, and serve as a positive electrode terminal and a negative electrode terminal, respectively. The positive electrode mixture 16 is made by kneading, for example, manganese dioxide with carbon as a conductive agent and a binder, molded and dried, and is in close contact with the inner bottom surface of the positive electrode can 10 . Negative electrode 2
0 is punched out in a circular shape from a light metal plate such as lithium, and is crimped onto the inner surface of the negative electrode terminal plate 12 either directly or via a current collector. Separator 18
For example, a nonwoven fabric made of polypropylene or glass fiber is used.

The lead terminal 22 is made of a strip-shaped thin metal plate, and only the two spots at the base end where it is spot welded are formed as circular concave thin-walled parts 24, and the thin-walled parts 24 are formed on the outside of the negative electrode terminal plate 12 located above the negative electrode 20. It is applied to the surface and spot welded. Reference numeral 26 indicates a nugget formed by welding, and in this embodiment, a circular thin portion 24 is formed as shown in the figure.
The lead terminal 22 is fixed to the negative terminal plate 12 by spot welding at two points.

Further, as shown by the imaginary line 28 in FIG.
Reinforce this part with step 8.

As mentioned above, since the thin wall portion 24 formed on the lead terminal 22 is spot welded to the negative electrode terminal plate 12, the welding current does not spread much from directly below the welding electrode, making it possible to effectively concentrate the welding current. can.

That is, if the lead terminal 22 is thick, when a spot welding electrode is pressed against the top surface of the lead terminal 22 and a welding current is applied, the current will spread from just below the electrode to the negative terminal plate 12 side. Therefore, a good nugget 26 cannot be formed unless a large welding current is applied for a relatively long period of time. In contrast, in the present invention, since spot welding is performed on the thin wall portion 24 which is sufficiently thinner than the other portions, the welding current does not spread, and therefore a good nugget 26 can be formed with a relatively small welding current and in a short welding time. be done.

This effect is achieved even in series spot welding in which both the positive electrode and the negative electrode are pressed against the lead terminal 22, while the electrode of one polarity is pressed against the negative terminal plate 12 side, and the electrode of the other polarity is pressed against the lead terminal 22 side. The same result can be obtained by indirect spot welding in which the electrodes are pressed against each other.

FIG. 3 shows a thin section 24 formed on the lead terminal 22.
This is an example of another form of . In this example,
A rectangular concave thin wall portion 24 is formed at the base end portion of the lead terminal 22, spot welding is performed at a plurality of locations inside the thin wall portion 24, and reinforcing adhesive is applied thereon. This embodiment also provides the same effects as the above embodiment.

Although the lead terminal on the positive electrode side is not mentioned in the above description, the lead terminal is also spot-welded to the positive electrode can 10 as necessary. If the present invention is applied to the lead terminal on the positive electrode side, good welding strength can be obtained with a small current and in a short time.

<<Effects of the invention>> As explained in detail above, according to this invention, the heat added to the inside of the battery when welding the lead terminal to the negative terminal plate is extremely reduced, and the lead terminal is welded sufficiently firmly. Ru. Therefore, without complicating the structure or assembly process of the battery, the occurrence of defective products in which the negative electrode melted by heat during welding penetrates the separator and reaches the positive electrode side is greatly reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the appearance of a flat nonaqueous electrolyte battery with lead terminals according to an embodiment of the invention;
FIG. 2 is a sectional view of the same battery, and FIG. 3 is a partial perspective view showing another embodiment of a thin wall portion formed on a lead terminal. 10...Positive electrode can, 12...Negative electrode terminal plate, 14...
... Sealing gasket, 16... Positive electrode mixture, 18...
Separator, 20... Negative electrode, 22... Lead terminal, 24... Thin wall portion, 26... Nugget, 28...
…glue.

Claims (1)

[Scope of utility model registration request] negative terminal plate 12, annular sealing gasket 14,
A negative electrode 20 made of a light metal, a separator 18, and a positive electrode mixture 1 are placed inside a flat battery case consisting of a positive electrode can 10.
6 are stacked and loaded, the negative electrode is in close contact with the inner surface of the negative electrode terminal plate, and a lead terminal 2 is placed on the outer surface of the central part of the negative electrode terminal plate corresponding to the negative electrode.
2 is a spot-welded non-aqueous electrolyte battery, and the spot-welded portion 24 of the lead terminal 22 is
A reinforcing adhesive 28 is applied to the spot welded portion.
A flat non-aqueous electrolyte battery with lead terminals, characterized by being coated with.