A review with references concerning development of a 300 Wh/kg solid-state rechargeable lithium battery is presented.The Oak-Ridge-developed LiPON technol. offers the promise of long-life, very safe, solid-state lithium batteries.Because of its thin-film construction, however, applications have heretofore been relegated to micro-batteries of small capacity and low specific energy.Front Edge Technol. (FET), which currently produces these micro-batteries, has embarked upon a program to develop large-capacity batteries of several hundred watt-hours.These batteries are projected to have specific energies of 300 Wh/kg and cycle-lives of over 1000 100%-DOD cycles.FET's tech. approach, performance and safety test-results to-date, and specific battery designs are presented.