ELECTROCHEMICAL CELL

PROBLEM TO BE SOLVED: To allow a positive electrode collector to be used at a high voltage by preventing melting of the positive electrode collector.SOLUTION: An electrochemical cell uses a container with a lid which comprises: a bottom-closed square cylindrical container; a metal ring located along an upper edge of the container; and a lid located on an upper part of the metal ring. A connection terminal having one end portion wired to the exterior is located inside a bottom plate of the container. The connection terminal and an optional active material are electrically connected to each other with a coating part interposed therebetween. In an electrical connection between the connection terminal and the inside of the container with the lid, an electrical connection area on the optional active material side is larger than an electrical connection area on the connection terminal side of the coating part.