Sheet-type secondary battery and manufacturing method therefor

Abstract

Provided is a sheet-type secondary battery capable of preventing damage to sheet-type electrodes when the sheet-type electrodes are connected, and also allowing an arbitrary number of the sheet-type electrodes to be laminated so as to easily realize a high-capacity sheet-type secondary battery and a manufacturing method therefor. In the sheet-type secondary battery, connecting parts between a positive electrode lead (3 a) and multiple sheet-type positive electrodes (11) and between a negative electrode lead (3b) and multiple sheet-type negative electrodes (13) are formed by laminating the multiple sheet-type positive electrodes (11) and the multiple sheet-type negative electrodes (13) on the corresponding positive electrode lead (3a) and on the corresponding negative electrode lead (3b), respectively, to thereby establish the connections therebetween, and the connection parts each have a conductive connection protective layer formed in between the laminated multiple sheet-type positive and / or negative electrodes.

Description

technical field [0001] The present invention relates to a sheet-shaped secondary battery and a method for producing the same. Although not particularly limited, the present invention relates to a large-capacity sheet-shaped secondary battery suitable for applications such as electric vehicles, UPS (uninterruptible power supply units), load balancing, and the like. its method of manufacture. Background technique [0002] [Patent Document 1] JP-A-2003-331816 [0003] [Patent Document 2] JP-A-2004-178860 [0004] In recent years, there has been a strong desire for downsizing and weight reduction of various electronic devices. Therefore, performance improvement of secondary batteries serving as power sources has been demanded, and various batteries have been developed and improved. The improvement of battery characteristics is expected to include higher voltage, higher energy density, higher load resistance, arbitrary shape, and assurance of safety. In response to such demand...

AI Technical Summary

Problems solved by technology

That is, there is a problem that it is difficult to set suitable welding conditions according to the thickness and hardness of the electrode lead and the sheet-shaped electrode as the workpiece.

[0010] For example, if excessive welding energy is applied to obtain sufficient welding strength, problems such as cracks and cracks will occur on the sheet-shaped electrodes.

Then, damages such as cracks and cracks to the thin electrode will become the main cause of failures such as electrode peeling and short circuit due to vibration, etc.

On the other hand, when the welding energy is insufficient, sufficient welding strength cannot be obtained, and problems such as an increase in battery resistance due to poor contact occur.

[0011] Then, this kind of problem occurs as the thickness of the workpiece is thicker, that is, the thickness of the stack of electrode leads and / or sheet-shaped electrodes is thicker, and the problem occurs more significantly.

[0012] That is, in the sheet-shaped secondary battery disclosed in the above-mentioned patent document in which the internal electrode pair is housed in a sealed state, the cross-sectional area (thickness) of the battery is large in order to achieve high output, high capacity, and low resistance. When the lead wire and the laminated metal foil-shaped sheet-shaped electrode are ultrasonically welded, it is difficult to obtain sufficient connection strength without damaging both, especially the thin sheet-shaped electrode.

In addition, under predetermined welding conditions, the number of stacked sheet-shaped electrodes that can be properly bonded to the electrode lead terminal is limited, which hinders the increase in the capacity of the sheet-shaped secondary battery.

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