Lithium-ion batteries have demonstrated excellent energy density, reliability, and life in commercial applications. Several new Navy and undersea applications are emerging that need the high energy density and high power capabilities that the lithium-ion technology offers. Such applications have historically utilized silver–zinc technology for their power source. However, life cycle costs, maintenance and logistics issues, and wet-life limitations are true detriments in these applications. Lithium-ion technology has demonstrated the energy and power density of silver–zinc, but with much improved cycle life, shelf life, and low maintenance properties. For these reasons, and others, many under water applications are looking to lithium-ion to provide the performance of the silver–zinc system, but at a greatly reduced life-cycle cost.