Packages for rechargeable lithium-ion batteries are broadly divided into metal can and pouch packages. While a metal can package, a container made of deep-drawn aluminum, provides high mechanical reliability, its drawback is low shaping flexibility. A pouch package is designed to seal with laminated films made of metal and resin. While pouch packages enable thinner package with its shaping flexibility, it has lower long-term durability and mechanical reliability, including the risk of electrolyte leakage compared to metal can package. To overcome the weaknesses of both types of packages, Toshiba have developed the cell using stainless steel for outer package.