JPH0644029Y2 - Battery with lead terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a battery with a lead terminal used, for example, as a backup power source for various electric devices, and particularly to a battery using a flat lithium battery.

<Prior art> In the case of batteries with lead terminals, one end of lead terminals such as lead plates and lead wires is spot-welded by resistance welding or laser welding to the terminal surface of batteries such as flat type batteries and cylindrical batteries. Direct connection is adopted.

By the way, when a flat lithium battery is used as the battery, for example, since this battery has a structure in which a thin layer of a lithium negative electrode is arranged on the inner surface of the negative electrode terminal, when welding the lead terminal to the outer surface of the negative electrode terminal, welding Due to the heat generated, the lithium negative electrode may be melted, and the molten lithium negative electrode may damage the separator, causing an internal short circuit of the battery.

For this reason, when this flat lithium battery is used, laser welding is generally used, which can suppress the thermal influence on the inside of the battery. When spot welding is performed by laser welding in this way, the laser beam is usually irradiated from above the lead terminal so as to focus on the vicinity of the contact area between the lead terminal and the battery terminal surface, and the peripheral area of this contact area is heated and melted. A welding method is used.

Then, when the battery is relatively thin (for example, a thickness of 2.5 mm or less), the welding energy is set to be low in order to suppress the thermal influence on the inside of the battery as low as possible. Further, in order to maintain the stability of the lead plate and the strength in the rotation direction, normally, as shown in FIG.
A structure with a distance of a to 10d is adopted.

In addition, if the welding strength is required and the welding effect on the battery is not so much concerned,
It is also proposed that the welding points 12a to 12d on the lead plate 12 are overlapped as shown in FIG.

<Problems to be Solved by the Invention> However, in the structure of FIG. 4 (A), the welding area between the lead terminal and the battery terminal surface at each welding point is small. Welding strength against welding is small, so subtle differences in the surface of the lead terminals (such as dirt and plating) and welding conditions (laser output, etc.) are likely to have a large effect on strength variations. There is a problem that the rate of peeling is large because the peeling strength to peeling is not stable.

On the other hand, when all the welding points are overlapped as shown in FIG. 4 (B), although the welding strength in the pulling direction and the peeling direction of the lead terminal is strong, the entire length of the welding point is shortened and the lead terminal The stability is poor, and the strength against the force in the direction of rotating the lead terminal with respect to the welding surface is insufficient, and the lead terminal is easily deformed.

An object of the present invention is to provide a battery with a lead terminal, which is less affected by heat inside the battery and which can improve and stabilize welding strength.

<Means for Solving the Problems> The battery with lead terminals of the present invention is a battery with lead terminals obtained by laser-welding lead terminals for current extraction on the battery terminal surface at three or more welding points. The gist of the present invention is that the two points are overlapped and the two overlapped welding points are separated from one or more other welding points.

When two welding points are overlapped (adjacent two welding points are overlapped) as described above, the overlapping interval, that is, the distance a between the centers of the two overlapped welding points is R of the radius of these welding points.
In this case, it is preferable that the range is 2R / 3 ≦ a ≦ 5R / 3. If the distance a is smaller than this range, that is, if the area where the welding points overlap is too large, the rate of defective battery characteristics increases due to the influence of heat generated by welding on the inside of the battery, and if this range is exceeded. That is, if the overlap is small, the peel strength of the lead terminal becomes small, and the necessary welding strength cannot be obtained.

Further, the distance b between the two overlapping welding points and one or more other welding points adjacent thereto (center distance between opposing welding points) may be b> 2R. If the distance b is less than this, the strength against the force in the rotation direction (moment direction) becomes insufficient, and there is a possibility that the lead terminal may be deformed.

<Operation> By overlapping every two welding points as described above, the welding area between the lead terminal and the battery terminal surface is increased, so that the welding strength is improved and the peel strength of the lead terminal can be increased.

Further, since the two overlapping welding points are separated from one or more other welding points, sufficient welding strength against the force in the rotational direction can be provided.

Furthermore, since the welding strength of the lead terminal can be increased in this way, it is possible to reduce the welding energy per welding point and suppress the thermal influence on the inside of the battery due to welding.

<Examples> Examples will be described below.

As shown in Fig. 1 (A), a coin-shaped lithium battery with a thickness of 1.6 mm (CR2016), which is constructed by housing the power generation element in a battery case that is made by combining a stainless steel battery can and a terminal plate.
The negative electrode terminal surface 2 and the positive electrode terminal surface 3 of 1 are laser-welded with lead plates 4 and 5 for current extraction made of a stainless steel plate having a thickness of 0.15 mm, respectively. Product) was produced.

The welding conditions were a voltage of 420 V and an energy of 2.8 joules / pulse, and four-point spot welding was performed using a YAG laser device.

At this time, the outer diameters of the melted portions at the welding points 4a to 4d between the negative electrode terminal surface 2 and the lead plate 4, that is, the nuggets were 0.7 mm in diameter (the same applies to the positive electrode terminal surface 2 and the lead plate 5). ).

In addition, the distance A between the centers of the first welding point 4a and the second welding point 4b, and the distance C between the centers of the third welding point 4c and the fourth welding point 4d, respectively. These two as about 0.5mm
Overlaid the dots. Further, the distance B between the centers of the second welding point 4b and the third welding point 4c is set to 1 mm, and these two points are separated from each other. FIG. 1 (C) shows a welded state of the lead plate 4 and the negative electrode terminal surface 2.

On the other hand, the four welding points 6a to 6d are set to 1 mm as shown in Fig. 2 (A).
Batteries with lead terminals that have the same configuration except that they are separated (comparative product)
Was produced. The welding conditions for the comparative product are 440V, 30
The energy was joule / pulse. Also, each welding point
The outer diameter of the nugget in 6a to 6d was 0.7 mm, and the distance between adjacent welding points was 1 mm. In this comparative product, the welding state between the lead plate 6 and the negative electrode terminal surface 7 is the second
It was as shown in FIG. 6B (same for the positive electrode terminal surface).

Each of these two kinds of batteries with lead terminals is made into 30 pieces, and the batteries are fixed with a fixing jig or the like, and the end portion of the lead plate 4 (6) is fixed as shown in FIG. 3 (A). While being sandwiched by the clamp member 8, it was pulled upward in the figure, that is, a 90 ° peel test of the lead plate was performed, and the welding strength was measured. The broken (perforated) state of the lead plate of the present invention in this test is shown in FIGS. 3 (B) and 3 (C), and the broken state of the comparative product is shown in FIG. 3 (D).

Further, the welding strengths and variations (standard deviations) of the both are as shown in Table 1, and the welding strength of the product of the present invention was larger than that of the comparative product and was stable with little variation.

In addition, each of these two types of batteries was made into 1000 pieces, and the voltage defect rate () and the external dimension defect rate (),
And the defective rate of welding strength () were investigated. The results are as shown in Table 2.

* 1 3kg or less was considered as defective.

* 2 It was not a defect due to melting of lithium.

The above is an example using a lead plate as a lead terminal,
In addition, it goes without saying that the present invention can be similarly applied to the case where a lead wire whose end portion on the welding side is processed into a flat plate shape is used.

<Effects of the Invention> As described above, according to the battery with the lead terminal of the present invention,
It is possible to reduce the heat effect on the inside of the battery,
Further, the welding strength can be improved and stabilized.

[Brief description of drawings]

FIG. 1 (A) is a perspective view of the product of the present invention, FIG. 1 (B),
(C) is an explanatory diagram of spot welding between the lead plate and the battery terminal surface in the product of the present invention, FIGS. 2 (A) and 2 (B) are explanatory diagrams of spot welding between the lead plate and the battery terminal surface in the comparative product, FIG. 3 (A) is an explanatory view of an experiment for measuring the tensile strength of the lead plate in these batteries, FIG. 3 (B),
(C) is an explanatory view showing the peeling state of the lead plate in the product of the present invention, FIG. 3 (D) is an explanatory view showing the peeling state of the lead plate in the comparative product, and FIGS. 4 (A), ( B) is an explanatory view of a conventional example. 2,7 …… Negative electrode terminal surface, 3 …… Positive electrode terminal surface, 4 to 6,10 to 13,
...... Lead plate, 4a ~ 4d, 6a ~ 6d, 10a ~ 10d, 12a ~ 12d, ...
Welding point.

Continuation of the front page (56) References Nakamura, Kobayashi, Morimoto "Modern Welding Technology, Large Series, Vol. 89 ~ 92

Claims (1)

[Scope of utility model registration request] 1. In a battery with lead terminals, wherein lead terminals for current extraction are laser-welded to three or more welding points on a battery terminal surface, and these welding points are overlapped every two, and the two are overlapped. A battery with a lead terminal, characterized in that the welding point is separated from one or more other welding points.