CYLINDRICAL LITHIUM ION SECONDARY BATTERY

摘要

An embodiment of the present invention relates to a cylindrical lithium ion secondary battery which can suppress the generation of an oxide layer, an increase in resistance, a short, and component cracks and/or sealing failure due to bending by optimizing the coating area and/or coating amount of solder or solder paste between a cap-up and a positive temperature coefficient device constituting a cap assembly. The cylindrical lithium ion secondary battery according to the present invention comprises: a cylindrical can; an electrode assembly received in the cylindrical can with an electrolyte solution; and the cap assembly for sealing the cylindrical can. The cap assembly includes: the positive temperature coefficient device connected to the electrode assembly; the cap-up connected to the positive temperature coefficient device, and the solder interposed between the positive temperature coefficient device and the cap-up. An external space unit without the solder is provided on the outer circumference of the positive temperature coefficient device and the cap-up.