JPH0429188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a lithium battery with a lead body in which a lead body is connected at least to the cathode can side.

Lithium batteries have an extremely long lifespan and have superior leakage resistance compared to alkaline batteries, so they are widely used as power supplies for IC memory backups. In these cases, lead bodies are often spot-welded directly to the cathode and anode cans of the battery, and the other ends of the lead bodies are soldered to the printed circuit board as they are.

FIG. 1 is a diagram for explaining a conventional manufacturing method of a lithium battery with a lead body. In the conventional method, a lithium battery is assembled in advance, and then lead bodies 8, 8' are spot-welded to predetermined locations on the cathode can 2 and the anode can 1, respectively.

That is, first, the anode 3 and the separator 4, which are mainly made of manganese dioxide, for example, are sequentially inserted into the bottom of the anode can 1. Apart from this, a wire mesh 7 is fixed to the inner surface of the cathode can 2 in advance by spot welding,
A cathode 5 made of metallic lithium is crimped and held on the wire mesh 7, and an annular gasket 6 is fitted around the outer periphery of the cathode can 2. The assembly of the cathode can 2, cathode 5, and gasket 6 is inserted through the opening of the anode can 1, and the opening of the anode can 1 is bent inward and tightened to complete the assembly of the battery. after that,
Lead bodies 8 and 8' were fixed to the cathode can 2 and the anode can 1 by spot welding, respectively.

However, this method has a problem when spot welding the lead body 8' to the cathode can 2. That is, the outermost layer of the cathode can 2 is usually a nickel layer, and a thin nickel plate is also used as the lead body 8'. Therefore, in order to reliably weld the lead body 8' to the cathode can 2, a temperature of around 1500° C. is required, but if spot welding is carried out under such high temperature conditions, the thermal influence on the cathode 5 will be large.
Since the melting point of metallic lithium is about 186° C., when the temperature is raised to the above-mentioned high temperature, a portion of the cathode 5 near the welding portion melts, which passes through the separator 4 and comes into contact with the anode 3, causing an internal short circuit. Further, as the separator 4, a non-woven fabric made of synthetic fibers, a microporous film, or the like is usually used, and the function of the separator 4 is lost due to the formation of holes in some parts due to the thermal effects during welding.

To prevent this from happening,
The cathode can 2 and the lead body 8' are spot welded using a small current.
Welding must be done in a short time, and welding conditions must be strictly controlled. Furthermore, when spot welding is carried out using a small current and a short time as described above, the welding strength between the cathode can 2 and the lead body inevitably becomes weaker, resulting in poor connection between the two.

The present invention has been made to solve the above-mentioned drawbacks, and includes a conductive plate-shaped body provided with a notch portion such that a rectangular bent piece is formed on the top surface of the cathode can before assembling the battery. The cathode can is arranged so as to fit within the diameter of the upper surface of the cathode can, and the parts other than the notches of the plate-shaped body are fixed to the cathode can by welding or welding as appropriate, and the cathode can with the plate-shaped body fixed is used to form a lithium battery. Then, by using the end of the notch as a folded part and folding back from the free end side of the notch to protrude outside the outer diameter of the battery to form a lead body, the cathode can and lead body are securely fixed. Moreover, it is possible to provide a method for manufacturing a lithium battery with a lead body that does not cause problems such as internal short circuits.

In the present invention, the cut portion in which the rectangular bent piece is formed preferably has a width of 2.5 to 3.0 mm and a length of 7 to 12 mm. In addition, the conductive plate-shaped body is equal to or slightly smaller than the inside diameter of the top surface of the cathode can13
A circular one with a diameter of ~15 mm is preferable in order to avoid getting caught when feeding the cathode can in the automatic battery assembly equipment. Since the mechanical strength as a lead body is poor, a thickness of 0.1 to 0.2 mm is preferable. The plate-like material may be of any conductive material, but nickel or stainless steel is particularly suitable.
Preferably, the material is annealed if necessary. If the above-mentioned material is plated with gold or silver, more stable conductivity can be obtained. In addition, it is necessary to weld or weld the plate to prevent the peripheral edge of the plate from rolling up or lifting during assembly and use. Spot welding is the preferred welding method; Ag50%,
The solder material may be melted by pressing with a soldering iron heated to 650° C. through the solder material having a composition of 15% Cu, 17% Zn, and 18% Al. Furthermore, in order to prevent contact with the lead body taken out from the anode can, when folding the lead body, it is necessary to fold it back so that it extends horizontally or upward.

Next, an embodiment of the present invention will be described using a lithium battery having a diameter of 20 mm and a total height of 1.6 mm. 2 to 6 are drawings showing embodiments of the present invention.

The cathode can 2 is made of a clad plate of nickel and stainless steel, and has a nickel layer 9 on the outside and a stainless steel layer 10 on the inside, as shown in FIGS. 2 and 3.
are placed respectively. The top surface of this cathode can 2 is made of nickel and has a circular shape with a diameter of 14 mm and a thickness of 0.15 mm, 1.0 mm smaller than the top surface of the cathode can 2, and a width of 3.0 mm and a length of 11 mm formed by the notch portion 11. Six locations of the plate-shaped body 13 having the lead body 12 are fixed in advance by spot welding. Note 15
is a spot weld.

Using this cathode can 2, a button type battery as shown in FIG. 4 is assembled. That is, the cathode can 2
A metal mesh 7 is fixed to the inner surface of the metal mesh 7 by spot welding, and a cathode 5 made of metallic lithium is pressure-bonded thereto. A gasket 6 made of a synthetic resin molded product is tightly fitted onto the outer periphery of the cathode can 2 .

On the other hand, an anode 3 made of a mixture of manganese dioxide and a conductive additive is inserted into the bottom of the anode can 1.
A separator 4 made of a nonwoven fabric of polypropylene fibers is placed thereon. Thereafter, the cathode can 2 holding the cathode 5 and gasket 6 is transferred to the anode can 1.
Then, the opening of the positive and negative cans 1 is bent inward and tightened to complete the assembly of the battery.

When using the battery, as shown in FIGS. 5 and 6, the terminal end of the notch 11 is folded back and the free end side of the notch 11 is folded back so that the lead body 12 protrudes outside the outer diameter of the battery. let
On the other hand, a rectangular lead body 16 is directly connected to the lower surface of the anode can 1 by spot welding.
Note that 17 is a spot weld.

The present invention is constructed as described above, and since the plate-shaped body is welded to the cathode can before assembling the battery, the heat generated during welding does not affect the cathode or separator. Therefore, internal short circuits do not occur, the conditions for welding the lead body and the cathode can can be arbitrarily selected, and the welding is carried out reliably, so that sufficient strength can be obtained.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view to explain the assembly process of a conventional lithium battery with a lead;
Figures 2 to 6 are for explaining embodiments of the present invention, and Figures 2 to 3 are a sectional view and a plan view of a cathode can to which a plate-shaped body is fixed, and Figure 4 is a cathode thereof. FIGS. 5 and 6 are a cross-sectional view of a lithium battery that has been assembled using a can, and are a front view and a plan view of the lithium battery with the lead body folded back. 2... Cathode can, 11... Notch, 12...
Lead body, 13... plate-shaped body, 14... folded part.

Claims (1)

[Claims] 1. Before assembling the battery, place a conductive plate-shaped body provided with a notch in which a rectangular bent piece is formed on the top surface of the cathode can so that it fits within the diameter of the top surface of the cathode can, and The parts of the plate other than the notch are fixed to the cathode can by welding or welding as appropriate, and a lithium battery is assembled using the cathode can to which the plate is fixed.Then, the end of the notch is used as a folded part, and the notch is A method for manufacturing a lithium battery with a lead body, characterized in that the lead body is made by folding back from the free end side of the part and protruding outward from the outer diameter of the battery.