The Defense Advanced Research Projects Agency (DARPA) is soliciting innovative solutions in foundational technologies to produce high-energy-density, high power-density electrically rechargeable batteries and fuel cells and rapidly transition them to end users. The program seeks to combine endurance and range advantages enabled by fuels with the logistical and operational advantages provided by electrical systems. Solutions may include room-temperature or higher-temperature devices and can be air-breathing or air-independent. Under this solicitation, DARPA is specifically seeking abstracts from Battery Developers for projects to advance core technology and manufacturing. Under separate cover, a solicitation will be issued at a later date to select End Users who will be responsible for integrating the resulting ExPEDitions technology into operational devices. Throughout this solicitation, the terms "Battery Developer" and "performer" may be used interchangeably to refer to the entities responsible for executing the technical objectives described herein.