NASA’s Sulfur Selenium Solid-State Battery Promising for Electric Aviation
NASA’s commitment to sustainable aviation continues with a prototype battery that boasts 500 watt-hours per kilogram energy density.
When not planning new trips into space, NASA has been researching how to improve the power of flights within the stratosphere.
NASA researchers John Connell and Yi Lin (seated) use a cyclic voltameter to check the performance level of a brand-new cathode the SABERS team created for their solid-state battery. Image used courtesy of NASA
NASA researchers have been making significant strides in developing an innovative battery pack that is lighter weight with enhanced safety features and superior performance compared to the batteries commonly found in vehicles and large electronics today. This is to support the organization’s commitment to sustainability by improving the solid-state battery technology available for electric aviation applications.
The Solid-state Architecture Batteries for Enhanced Rechargeability and Safety (SABERS) program continues to surpass expectations and is expanding the possibilities of battery power. The most recent prototype has an energy density of 500 watt-hours per kilogram, which exceeds conventional lithium-ion batteries.
NASA SABERS Design
NASA’s SABERS program was started to create a safer, more efficient, and more resilient battery than lithium-ion batteries. The decision to design solid-state batteries proved to have lower safety risks and higher resilience because of the liquidless design.
Examining the unique combination of sulfur and selenium was advantageous for both the electric capacity of the design and the procurement of materials. As a byproduct of oil refining, sulfur is a globally ubiquitous element.
The project aims to forge a novel battery by combining elements that have never been united. One such element is "holey graphene," a NASA-developed component renowned for its remarkable electrical conductivity, owing to the holes on its surface that permit air passage. Notably, this material possesses extraordinary attributes—it is incredibly lightweight and environmentally friendly.
This research also sets a precedent for battery use in aviation by showing that safer batteries are technically possible and cost-effective.
Benefits of Solid-State Batteries
Battery performance plays a pivotal role in the growth of the sustainable electric aircraft industry. Batteries must efficiently store the immense amount of energy needed to power an aircraft while maintaining a lightweight profile.
For a long time, lithium-ion batteries were better equipped to discharge stored power more rapidly than solid-state batteries. However, the work from the SABERS researchers ‒ in partnership with Georgia Tech ‒ has enhanced the discharge rate of solid-state batteries tenfold since the start of their research.
Their efforts have also made solid-state batteries up to 40 percent lighter with the ability to stack the sulfur selenium battery cells on top of each other without a surrounding casing.
By eliminating the casing around individual cells, a remarkable increase in energy storage (possibly two to three times greater) within a given space becomes possible — a tremendous advantage when integrating batteries into an aircraft's structure. This advancement also translates to smaller and lighter cooling systems for the cells.
NASA's solid-state sulfur selenium batteries exhibit exceptional resilience, withstanding temperatures twice as hot as conventional lithium-ion batteries. Additionally, these batteries are less susceptible to pressure fluctuations, common during takeoff and landing.
These arguably groundbreaking innovations are promising in the world of electric flight.
Cost is a significant determining factor, particularly when adopting new components for commercial aircraft.
These components' testing protocols are more rigorous than those used for ordinary vehicles. While the expense of a sulfur selenium battery for a passenger vehicle might be prohibitive, the economics change when applied to airlines and air taxi companies, which can spread the cost over thousands of flights, making it a more feasible and economically sensible option for them.
NASA’s Plans for Air Travel
According to NASA, as the possibilities for sustainable aviation grow, advanced air mobility (AAM) may be the next big thing.
Aviation industry innovators are actively designing rideshare air services connecting homes to airports. The advent of remotely piloted and autonomous aircraft is set to revolutionize air travel, making it more accessible to the public than ever before, and will likely rely solely on battery power.
Battery designs are expected to power future electric aircraft. Image used courtesy of NASA
In this pursuit, NASA is diligently studying the safe integration of these aircraft into the current airspace system and delving into the technological requirements necessary for a successful transition to the highly digital future airspace. These aircraft would facilitate seamless transportation within urban areas, between neighboring cities, and even to destinations primarily accessed by car.