A battery comprises a battery cell having two voltage terminals and a flexible sidewall; a wall structure against which the battery cell is located, the wall structure including a sidewall that is adjacent to the sidewall of the battery cell; and a tooth structure that extends away from the sidewall of the wall structure and towards the sidewall of the battery cell, wherein the tooth structure includes a distal end sufficiently sharp to puncture the flexible sidewall of the battery cell when the flexible sidewall of the battery cell is forced up against the tooth structure due to a build up of excess pressure inside the battery cell.