Container for energy storage device including full penetration welded sealing member and method of producing the same

A method of producing an energy storage device including a container containing an electrolyte, the method comprising:

• positioning a sealing member on the container to cover a through hole formed in the container for injecting the electrolyte;
• and
• forming a full penetration weld portion by full penetration welding the sealing member to the container,
• wherein the sealing member includes a fixing portion arranged outside the container, the fixing portion including a thin-walled portion which is thinner than a remaining portion of the fixing portion,
• wherein the full penetration weld portion is formed by full penetration welding the thin-walled portion to the container, and
• wherein an entirety of the full penetration weld portion is located away from an outer edge of the sealing member, the full penetration weld portion penetrating into the sealing member in a thickness direction of the sealing member.

An energy storage device, comprising:

• a container;
• a through hole formed in the container for injecting an electrolyte;
• a sealing member that covers the through hole, the sealing member being located outside the container and comprising a thin-walled portion and a thick-walled portion surrounding a periphery of the thin-walled portion, the thick-walled portion having a thickness more than a thickness of the thin-walled portion;
• and
• a full penetration weld portion that welds the thin-walled portion to the container by a full penetration welding, through the thin-walled portion, into the container,
• wherein an entirety of the full penetration weld portion is located away from an outer edge of the sealing member, the full penetration weld portion penetrating into the sealing member in a thickness direction of the sealing member.