Safety mechanism for rectangular battery and method of manufacturing the same

摘要

A battery case (1) has a cutting groove (10) formed on its elongated side surface (1a). Between a groove bottom surface of the cutting groove (10) and an inner surface of the battery case (1) is provided a thin-walled easily-rupturable portion (12) designed to rupture at an instant when an internal pressure of the battery case (1) reaches a predetermined value. Thereby, a safety mechanism for use with a prismatic battery is realized. The manufacture of the safety mechanism is as follows. A cutting blade (37) rotated at a high speed by a high-speed rotary body (30) is brought into cutting engagement with the elongated side surface (1a) of the battery case (1) of the prismatic battery in finished form until it reaches a predetermined depth and is fixed, and subsequently the high-speed rotary body (30) or the prismatic battery is brought into rectilinear relative movement.