Electric power storage device

A power storage device comprising:

• an electrode assembly;
• a case, which accommodates the electrode assembly;
• an electrode terminal, which supplies and receives power to and from the electrode assembly;
• a conductor, which connects the electrode assembly to the electrode terminal;
• a current interruption mechanism, which interrupts a current-carrying path between the electrode terminal and the electrode assembly when an internal pressure of the case reaches an interruption activation pressure;
• and
• a pressure release valve, which is located on a wall portion of the case and releases the pressure in the case to the outside of the case when the internal pressure of the case exceeds a valve activation pressure, wherein
• the current interruption mechanism includes
• a conducting portion, which allows current to flow between the electrode terminal and the conductor, and
• a deformation plate, which contacts the conductor and defines, in the case, a first space, a pressure in which is equal to the internal pressure of the case, and a second space, a pressure in which is maintained at a pressure outside the case, wherein a contact portion between the deformation plate and the conductor is sealed,
• the current interruption mechanism is configured such that, when the internal pressure of the case reaches the interruption activation pressure, the deformation plate receives the internal pressure and is deformed to break the conducting portion,
• the current interruption mechanism is further configured such that, when the internal pressure of the case exceeds a sealing portion withstanding pressure, which is defined as a pressure that is set for maintaining the sealing at the contact portion, a sealing function at a sealing portion is lost, thereby releasing the pressure in the case to the outside of the case from the first space via the second space,
• in a case in which the electrode assembly expands and contracts in accordance with normal charging and discharging, a pressure that is set for maintaining the shape of the case within a range in which the case expands and contracts in accordance with the expansion and contraction of the electrode assembly is defined as a case withstanding pressure,
• the sealing portion withstanding pressure and the valve activation pressure are set higher than the interruption activation pressure and lower than the case withstanding pressure, and
• the sealing portion withstanding pressure is set higher than the valve activation pressure.

A power storage device comprising:

• an electrode assembly;
• a case, which accommodates the electrode assembly;
• positive-electrode and negative electrode terminals, which supply and receive power to and from the electrode assembly;
• a current reduction mechanism, which reduces current from the electrode terminals to the electrode assembly when the internal pressure of the case reaches an activation pressure;
• and
• a pressure release valve, which is located on a wall portion of the case and releases the pressure in the case to the outside of the case when the internal pressure of the case exceeds a valve activation pressure, wherein
• the current reduction mechanism includes
• a short-circuit member electrically connected to one of the electrode terminals, and
• a deformation plate, which is arranged to be in contact with the case and defines a first space, a pressure in which is equal to the internal pressure of the case, and a second space, a pressure in which is maintained at a pressure outside the case, wherein a contact portion between the deformation plate and the case is sealed,
• the current reduction mechanism is configured such that when the internal pressure of the case reaches the activation pressure, the deformation plate is deformed by receiving the internal pressure and allows current to flow through the short-circuit member via the deformation plate,
• the current interruption mechanism is further configured such that, when the internal pressure of the case exceeds a sealing portion withstanding pressure, which is defined as a pressure that is set for maintaining the sealing at the contact portion, a sealing function at a sealing portion is lost, thereby releasing the pressure in the case to the outside of the case from the first space via the second space,
• a pressure that is set for maintaining the shape of the case is defined as a case withstanding pressure,
• the sealing portion withstanding pressure and the valve activation pressure are set higher than the activation pressure and lower than the case withstanding pressure, and
• the sealing portion withstanding pressure is set higher than the valve activation pressure.