Lithium-water power source for low power-long duration undersea applications

Battery requirements for deep-ocean operation in areas of low dissolved oxygen were set at 2 watts (for a minimum of one year) at an operating voltage of at least 0.75 volts. The maximum battery system weight was not to exceed 50 lbs. The ability of the lithium-water electrochemical couple to satisfy these requirements has been demonstrated. Short-term high-pressure testing defined performance up to 10000 psi. Stable multiweek performance was demonstrated at ambient pressure. Specific energy based on lithium ranged from 1800 to 2400 Wh/kg, sufficiently high to achieve the system weight goal of 50 lbs. A proprietary electrolyte management scheme was developed to admit the proper flow of water into the battery while retaining the electrolyte alkalinity required to control the reactivity of the lithium. The scheme was demonstrated over a six month test period. The lithium-water electrochemistry, integrated system concept, test results, and the design configurations chosen for ocean deployment are described