In the world of battery technology, the trade off between power and energy has flustered experts for years. Energy measures the capacity to do work, while power measures how fast the work can get done. An increase in one of these variables, often comes at the expense of the other.
As the Army’s equipment continues to become more power hungry and the desired run time remains “as long as possible,” researchers at the U.S. Army Materiel Command’s Communications-Electronics Research, Development and Engineering Center, or CERDEC, are developing a new lithium ion battery hybridized with other materials that can meet both demands in a package small enough for soldiers to carry in the field.
“What we’re able to do with these hybrids is get long run times, but also provide the power necessary to do the actual mission,” said Terrill Atwater, CERDEC Command Power and Integration Directorate research chemical engineer. “One of the two components alone would either power the mission for a very short period of time or not power it at all.”
CERDEC’s hybrid battery would also provide another advantage: lighter loads for soldiers. The hybrid battery is lighter in weight than the batteries soldiers currently carry, but it provides the same high pulse power and high energy.
“All soldiers want to do is complete their missions without swapping out batteries,” Atkins said. “Ultimately, that’s what we’re providing them. The capability to do their mission without swapping out batteries because they have too low power or energy.”
The goal for CERDEC’s hybrid battery is to double the energy density of the Army’s battery technology from the currently fielded 200 watt-hours per kilogram to 400 watt-hours per kilogram, effectively doubling the amount of energy in the same weighted volume package. They also plan to surpass the Army’s 72-hour run time requirement, which is out of reach for current lithium ion technology. Researchers said they hope to begin fielding the hybrid technology in the coming years.
The main obstacle to achieving this landmark accomplishment? Safety.
“The energy content of the technologies we deal with in the military for portable applications contains the same energy as a half a stick of dynamite,” said Mike Brundage, chief for the CERDEC Command, Power and Integration's Tactical Power branch. “We’ve demonstrated the chemistry in the lab. Whether or not it can be done in a package that is safe for soldiers to use is still to be determined.”