Cylindrical cell and manufacturing method thereof

Abstract

A cylindrical cell includes; a group of electrode plates (5); a positive electrode collector (10) welded to a core protrusion of the positive electrode in the group of electrode plates (5); a negative electrode collector (11) having a plurality of projections (12) protruding to the lower surface and having the upper surface welded to a core protrusion of the negative electrode in the group of electrode plates (5); a metal case (7) containing the group of electrode plates(5) having the welded positive / negative electrode collectors (10, 11) with the negative electrode collector (11) downward and the projections (12) of the negative electrode (11) welded to the inner bottom surface; electrolytic liquid contained in the metal case (7); and a sealing body (9) electrically insulated from the metal case (7) and sealing the upper portion of the metal case (7). The projections (12) of the negative electrode collector (11) are arranged at a plurality of positions in the region between the portion opposing to the hollow cylindrical portion (5a) and a peripheral portion. Thus, the cylindrical cell can have a high resistance against a large current discharge and a high metal case pressure.

Description

technical field [0001] The present invention relates to a cylindrical battery with a spirally wound electrode plate group and a manufacturing method thereof. Background technique [0002] There are many kinds of cylindrical batteries, and nickel-cadmium batteries and nickel-metal hydride batteries are representative. Since these cylindrical batteries are highly reliable and easy to maintain, they are widely used in various applications such as power supplies for mobile phones and notebook computers. Furthermore, in recent years, the development of cylindrical batteries suitable for large current discharge has been demanded as a power source for electric assist bicycles, lawn mowers, and even electric vehicles. [0003] This type of cylindrical battery for large current is stacked with a strip-shaped positive electrode plate and negative electrode plate sandwiching a separator for isolation, the whole is wound in a spiral shape to form an electrode plate group, and the elect...

AI Technical Summary

Problems solved by technology

[0005] However, in the above-mentioned conventional structure, since the metal case and the negative electrode current collector are connected by only one point of welding, there is a problem that the connection resistance between the metal case and the current collector is high.

For example, when discharging with a large current of 100A, there is a problem that the voltage of the battery drops rapidly due to the high resistance of the welded part of the metal case and the negative electrode current collector.

In addition, as in Figure 12 When the tongue-shaped connecting piece 22 is welded to the metal shell as shown, the conduction resistance of the tongue-shaped connecting piece 22 itself is large, and the tongue-shaped connecting piece 22 may melt when a large current flows. And the problem of breaking

In addition, as disclosed in Japanese Patent Application Laid-Open No. 2000-106165, when the welding protrusion at the center of the bottom surface of the metal case is welded to the negative electrode current collector, if the internal pressure of the battery increases due to the overcharged state of the battery, etc., the metal The bottom surface of the case expands, and the negative electrode current collector is also deformed in the same way, and the welded part with the negative electrode plate may be peeled off, which may increase the resistance of the battery.

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