Safety device for a sealed cell

Method of preventing pressure in a lithium-ion sealed cell from exceeding a certain level, comprising:

• providing a container, the container comprising:
• a lateral wall;
• an end wall that is closed by a wall electrically connected to the lateral wall;
• a cover opposite the end wall;
• and
• thinning a thinning portion of said end wall;
• providing alternating positive and negative electrodes in the container, respectively connected to positive and negative current output terminals;
• wherein at least one of the positive electrode and positive output terminal and the negative electrode and negative output terminal are electrically connected through the thinning portion;
• and
• providing a connection strip which connects at least one of the positive electrodes and the negative electrodes to the end wall of the container;
• operating the sealed cell,
• wherein the thinning portion is capable of a complete tear and a partial tear, respectively, at an instance when the thinning portion is torn by excess pressure inside the container,
• a complete tearing of the thinning portion results in simultaneously exhausting gas and interrupting electrical conduction between the at least one of the positive electrode and positive output terminal and the negative electrode and negative output terminal, and it is the tearing of the thinning portion that both exhausts gas and interrupts electrical conduction, and
• a partial tearing of the thinning portion results in exhausting excess pressure and not interrupting the electrical conduction.