Patent ID: 7776469

Claim:
A secondary battery comprising: an electrode assembly comprising a positive electrode, a negative electrode, and a separator interposed therebetween, the positive electrode, negative electrode and separator wound in a spiral; a case in which the electrode assembly is contained; a cap assembly which seals the case and which is electrically connected to the electrode assembly; and a negative current collecting plate electrically connecting the negative electrode and the case, the negative current collecting plate comprising at least one partially surface-treated region to which the negative electrode of the electrode assembly is fixed, wherein the negative current collecting plate comprises at least one first contact region upon which the at least one partially surface-treated region is located, and at least one second contact region which is fixed to the case, and the negative electrode and the first contact region comprise a first material, and the first contact region is surface-treated with a second material different from the first material to form the surface-treated region.