Closure assembly with low vapor transmission for electrochemical cell

An electrochemical cell, comprising:

• a cylindrical metal container having a closed bottom end, a sidewall and an open end;
• a spirally wound electrode assembly disposed within the container, said electrode assembly comprising a positive electrode, a negative electrode consisting essentially of lithium or a lithium alloy, a separator disposed between the positive and negative electrodes, and a non-aqueous volatile electrolyte;
• a circumferential inward projection in the sidewall and having an upper wall and a lower wall connected by a transition member, the upper wall inclined upwardly towards a radial center of the cell, and the upper wall spaced apart from the lower wall along their respective lengths;
• an end assembly closing the open end of the container, the end assembly comprising a vent member capable of venting at a predetermined internal pressure, a current limiting or interrupting member, and an insulating, polymeric seal member located between the container and a conductive contact of the end assembly, and wherein the conductive contact is operatively electrically connected to the positive electrode or negative electrode;
• and
• wherein the bead upper wall has a lowermost point located radially outward from an upper wall uppermost point, and wherein an angle between an imaginary horizontal line extending through upper wall lowermost point and an imaginary line between upper wall lowermost point and upper wall uppermost point is from 1° to 30°;
• and
• wherein one of (a) and (b) applies:
• a) (i) the contact assembly further includes a conductive contact member having a peripheral flange connected to a pressure release vent member, the pressure release vent member capable of rupturing in response to internal cell pressure that is at least as high as a predetermined release pressure thereby allowing matter to escape through the vent member, (ii) the peripheral flange includes an axial segment that extends an axial distance substantially parallel to a segment of the sidewall adjacent thereto and a radial segment extends from the axial segment in a substantially radial direction and includes a portion located axially above the bead so that the peripheral flange transitions from the radial segment to a second lower axial segment in a substantially axial direction at least 0.25 mm axially below the upper wall uppermost point of the bead, and (iii) the seal member is under compression between at least (a) the sidewall and peripheral flange axial segment, (b) the bead and the radial segment, and (c) the bead and the second lower axial segment;
• and
• b) (i) the end assembly further includes a conductive inner cover in operative electrical contact with the conductive contact and having first and second axial segments, with the second axial segment located radially inwardly from the first axial segment and having a difference in length of less than 20% in comparison to the first axial segment, and a radial segment connecting the first and second axial segments, and (ii) the seal member is compressed between the radial segment and the upper wall of the bead and between the inner cover axial segments and an upper sidewall of the container.