Small-scale lithium-ion batteries have been widely used for portable equipment because of their high energy and power densities. Realization of large-scale lithium secondary batteries is expected for their applications to electric vehicles and stationary electric energy storage. So that, since 1992 in the "New Sunshine Program", the R & D of the technologies for distributed electric energy storage is going on and two types of lithium secondary batteries are being developed. One of important issues is clarifying thermal behaviors of the batteries, because the battery temperature affects the performance, the reliability and the safety of batteries. A joint research on thermal simulation technology for lithium secondary batteries between Electrotechnical Laboratory (ETL) and Lithium Battery Energy Storage Technology Research Association (LIBES) has been carried out since 1994^1). This paper describes the research results obtained in ETL and three commission companies to LIBES.
