Patent ID: 8003243

Claim:
A secondary battery, comprising: a spirally wound body formed through laminating a cathode which includes a cathode active material layer on a strip-shaped cathode current collector and an anode which includes an anode active material layer on a strip-shaped anode current collector with a separator in between, and spirally winding the cathode and the anode, wherein: the anode includes an anode active material comprising: a CoSnC-containing material having a phase containing tin, cobalt and a first carbon, wherein a first carbon content ranges from about 9.9 wt % to about 29.7 wt %, a ratio of cobalt to a total of tin and cobalt ranges from about 30 wt % to about 70 wt %, and a 1s peak of the first carbon is obtained in a region lower than 284.5 eV by X-ray photoelectron spectroscopy; and a second carbon, the cathode includes an exposed cathode region in an outer end portion of the cathode, the exposed cathode region being a region in which the cathode current collector is not covered with the cathode active material layer and is exposed, the exposed cathode region includes an insulating protective member on at least one of an outer side and an inner side of the exposed cathode region in a position opposed to an outer end portion of the anode active material layer in a single turn inside the outer end portion, and the protective member is formed so as to have a width that ranges from about 0.5 mm to about 5 mm larger than the width of the cathode current collector.