JAMSTEC aims to develop a long cruising range AUV (LCAUV) which equipped with a hybrid power source to travel over 1000 km. A PEFC system and a lithium-ion battery system are considered as the hybrid power source. The both system will be downsized to make the LCAUV smaller. In this article we describe the high energy type lithium-ion battery system under development. The battery system for the underwater vehicle consists of three major parts: a lithium-ion battery cell-assembly, a pressure-balanced case, and a battery manager. The cell-assembly is composed of sheet-type sealed battery cells and a chassis. The seal method for 110 MPa pressure-tight has been jointly developed by JAMSTEC and ENAX. The manager is needed for battery charge and discharge process management particularly when the vehicle equipped with the battery system is deployed. We have already achieved a high energy lithium-ion battery cell which energy density is about 300 Wh/liter by the addition of nickel compound into its cathode. To enhance this performance we now try to modify its anode material and configuration.
In recent years, deep-sea research becomes important to assess environmental problems including global warming since oceans cover 70 % of the Earth's surface. Survey and mining of natural resources in the region of deep-sea and seabed are also needed to keep lasting economic growth. Until now, we have, however, held survey of a tiny percent of entire oceans because of deep-sea-bound. Human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) are widely used for deep-sea research since 1980s (Doyle, 1995). The evolution of electrical and electronic engineering technology over the last decade has led to improvement in autonomous underwater vehicle (AUV) development. The advantages of AUV utilization are reducing operation cost because of support ship less, and enabling them to go where HOVs or ROVs have trouble reaching.
