Type of cap for cylindrical lithium battery and new type of cylindrical lithium battery

A cylindrical lithium battery, comprising:

• a cap for a cylindrical lithium battery, comprising:
• a steel sheet, the steel sheet being defined with a through hole;
• an explosion-proof disc, the explosion-proof disc being arranged on one side of the steel sheet, and the explosion-proof disc being provided with a wrap edge, the wrap edge extending from an edge of the steel sheet to another side of the steel sheet and then to an edge of the through hole;
• a connection piece, wherein a middle portion of the connection piece is in contact with a middle portion of the explosion-proof disc;
• a spacer ring, the spacer ring being arranged between the explosion-proof disc and the connection piece;
• and
• a seal ring, the seal ring being arranged around the explosion-proof disc, the connection piece and the spacer ring,
• wherein the explosion-proof disc is recessed toward the connection piece to form a groove at a periphery thereof, and the spacer ring is received in the groove of the explosion-proof disk, such that a cross-sectional profile of the spacer ring conforms with a cross-sectional profile of the explosion-proof disk,
• wherein the edge of the through hole is provided with a flange, and the flange is in contact with an inner wall of the groove.