Patent ID: 8852771

Claim:
A battery including: a cylindrical shaft core having a bore extending in an axial direction; and a wound electrode assembly formed by winding a first electrode plate, a second electrode plate, and separators around an outer circumference of the cylindrical shaft core, the wound electrode assembly including: a first wound portion formed by a wound first active material-uncoated portion of the first electrode plate, the first wound portion constituting a distal end of the wound electrode assembly in the axial direction, a second wound portion formed by a wound second active material-uncoated portion of the second electrode plate, the second wound portion constituting a rear end of the wound electrode assembly in the axial direction, and a power generating portion located between the first wound portion and the second wound portion in the axial direction and formed by the first electrode plate, the second electrode plate, and the separators wound together, wherein the shaft core includes a metal current collector portion having a current collector joint portion to be joined with the first wound portion or the second wound portion, wherein portions of the first wound portion or the second wound portion located on a radially outer side of the shaft core relative to the current collector joint portion are overlapped and welded to the current collector joint portion, wherein the shaft core includes a protruding portion protruding from the wound electrode assembly towards the distal end in the axial direction; wherein the battery includes: a cylindrical case body with a bottom for accommodating the wound electrode assembly, a lid member closing an opening of the case body and having an insertion hole, into which the protruding portion is inserted, and a safety vent closing a distal end opening of the protruding portion, the safety vent being capable of opening when internal pressure of the battery reaches a predetermined vent-opening pressure to discharge gas introduced into the bore of the shaft core inside the battery through the bore from the safety vent to the outside of the battery, wherein the protruding portion of the shaft core includes a through hole extending through the wall forming the protruding portion at a position further on the rear end side in the axial direction than the lid member, or, a cut-out formed by cutting off part of the wall forming the protruding portion from a distal end of itself to a position further on the rear end side in the axial direction than the lid member; wherein the lid member is an external electrode terminal made of metal and exposed to the outside of the battery; wherein the protruding portion protrudes out of the case body through the insertion hole; and wherein protruding portion is a part of the current collector portion, and the protruding portion is welded to a portion of the lid member, located around the insertion hole.