carbon electrodes has the potential to be a very big deal.
Starting this year, we are also working on molten lithium sulfur for grid stor- important to the Army to manage power and energy in a smart way by reducing logistical burdens,
increasing generator
renewables. But using renewable energy requires storage; hence the need for new storage solutions.
REDUCING SOLDIERS’ LOAD What can a Soldier expect to have in the night vision, guidance system, lasers, battery. The average Soldier carries 16 pounds of batteries for a 72-hour mis- sion. Depending on the Soldier’s role in a platoon, it could be up to 32 pounds of batteries. The more electronics Soldiers carry,
the more batteries they’re going
to have to carry. Our research has the potential to substantially reduce the bat- tery weight, allowing for Soldiers to carry more ammunition or water.
Everything we do at the lab is done with the consideration of empowering, unbur- dening,
and protecting Soldiers. Our
main goal is to support the Soldier, whose needs are more stringent than what is needed commercially. For instance, Sol- diers need batteries that operate in a wide temperature range, from -40 degrees to
+70 degrees Celsius. Commercially, bat- tery users generally are looking at a range of -20 to +40 degrees.
temperature-related. Working on the fundamentals and looking at the inter- face allows us to understand what limits operations at low temperatures. Through
ASC.ARMY.MIL 61
that understanding, we have been able to develop these new additives and materials.
We have been able to make only incre- mental improvements over the years, however. Typically, improvements in energy density have averaged about 1 per- cent a year, with a few step changes, such as the emergence of lithium-ion batteries.
Ultimately, we believe batteries will start looking more like fuel cells, such as the metal air batteries, or semi-fuel cells.
OVERCOMING LIMITATIONS What limits us? Right now the Lithium 145 battery, which the Army uses, is rated at 145 watt-hours per kilogram. Our goal, which is achievable, is to increase that to 300 watt-hours per kilogram.
In battery chemistry, we are limited by the periodic table, with lithium on one
thermodynamically constrained by the amount of power and energy that we can develop in a battery.
To counter that, we are looking at new stra- tegic areas by designing systems to allow in any environment using indigenous or other available sources such as wastewater.
Some of our new programs are looking at how we could make fuel out of water. One of our long-term goals, for example, is to determine whether we can split water and make hydrogen that could be used as fuel in a fuel cell or small engine. Nature splits water, taking water and car- bon dioxide and making energy. We are trying to short-circuit this process and proteins that are found in spinach, for
RESEARCH IN ACTION Dr. Kang Xu, Senior Research Chemist at the U.S. Army Research Laboratory (ARL), is one of the inventors responsible for an electrolyte additive that allows batteries to operate at a previously unheard-of 5 volts, opening the door to a whole new class of batteries and voltages. (Photo by Conrad Johnson)
SCIENCE & TECHNOLOGY
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