Cylindrical secondary battery having structure in which electrode assembly is connected with sealing cover via combination of current collector plate and current collector lead

1. A cylindrical secondary battery, comprising:

an electrode assembly that is composed of a positive electrode plate and a negative electrode plate with a separator therebetween that are overlaid with each other and spirally wound;

an outer casing that has a cylindrical shape with a closed bottom, and houses therein the electrode assembly;

a sealing cover that seals an opening of the outer casing, and is one of electrode terminals;

a current collector assembly that is inserted between the electrode assembly and the sealing cover, and electrically connects the sealing cover with a core of one of the positive electrode plate and the negative electrode plate, wherein

the current collector assembly is composed of a combination of (i) a current collector plate having a plate shape that is provided on an end surface of the electrode assembly in a side in which the sealing cover is provided, and is joined to the core and (ii) a current collector lead that includes a cylindrical part having an axis in a direction along a main surface of the current collector plate,

the cylindrical part includes a top part and a bottom part whose peripheral surfaces oppose each other,

the top part is welded and joined to a sealing plate that is a bottom surface of the sealing cover, and the bottom part is welded and joined to the current collector plate,

the current collector lead further includes at least one tab part having a rectangle shape that extends from an opening edge of the cylindrical part in a direction of the axis,

the tab part has a middle portion bent to have a wave shape with an amplitude in a direction that connects the current collector plate with the sealing cover, the middle portion being between a root portion and a tip portion of the tab part,

the tab part is electrically connected with the current collector plate at the tip portion by welding and joining the tip portion to the current collector plate, and

the tab part contacts with the current collector plate at a wave trough of the middle portion, and is further electrically connected with the current collector plate at the wave trough.

2. The cylindrical secondary battery of claim 1 , wherein

the middle portion is bent to have an S-shape or a Z-shape, and contacts with the sealing cover at a wave crest of the middle portion.

3. The cylindrical secondary battery of claim 1 , wherein

a part of the current collector plate with which the wave trough contacts is cut and raised toward the tab part.

4. The cylindrical secondary battery of claim 1 , wherein

the tab part extends from the opening edge of the top part of the cylindrical part.

5. The cylindrical secondary battery of claim 1 , wherein

the current collector lead has a plurality of projections formed therein, and is welded and joined to the current collector plate and the sealing cover at the projections as welding points.

6. The cylindrical secondary battery of claim 1 , wherein

the current collector lead is a single metal plate that has been bent.

7. The cylindrical secondary battery of claim 1 , wherein

the cylindrical part of the current collector lead is flat, and has a height, in a connection direction that connects the current collector plate with the sealing cover, that is smaller than a width in a direction perpendicular to the connection direction.