eVTOL battery power demand needs more research, says Oak Ridge Lab study

eVTOL battery power demand needs more research, says Oak Ridge Lab study

eVTOL battery power demand needs more research, says Oak Ridge Lab study 800 480 Energy Storage Journal

March 27, 2024: Sky-high ambitions for widespread use of electric aircraft could face significant challenges without new technology to boost battery cycle life, according to research by the US Oak Ridge National Laboratory.

Initial results of the lab’s research, published on March 12, show that high rates of discharge required at takeoff by electrical vertical-takeoff-and-landing (eVTOL) aircraft could significantly reduce battery cycle life.

Unlike EV batteries, which typically drain at a steady rate, eVTOL batteries need varying amounts of power for flight stages such as climbing, hovering and descent — with some phases requiring high bursts of power, Oak Ridge researchers said.

The research team made lithium ion batteries at the Department of Energy’s Battery Manufacturing Facility at Oak Ridge and ran them through simulated climb stages of eVTOL aircraft.

Scientists studied what happened inside the battery during cycling — including how much energy was rapidly accessible during the demanding takeoff phase — then tested the battery materials afterward for corrosion and other chemical or structural changes.

The study incorporated testing of a new Oak Ridge-developed electrolyte compared to what the research team said was “the current state-of-the art version” used in lithium ion batteries.

Using the eVTOL research criteria the Oak Ridge electrolyte performed better, retaining more capacity during the most power-demanding flight phases.

Oak Ridge lead researcher Marm Dixit said the results show the need to diversify how battery performance is measured.

“Your battery is not just capacity at the end of 1,000 cycles. It’s what’s happening within a cycle that tells you whether your system is going to work or crash,” Dixit said.

“And the stakes are much higher here because you’re asking ‘how safe it is to go up in the air?’ This is a question we don’t know the answer to — yet.”

Now more is known about what is required by eVTOL batteries, systems will need to be engineered differently to achieve that, Dixit said.

Image: The operating phases of an eVTOL need varying amounts of power. Some require the battery to discharge high amounts of current rapidly, reducing the distance the vehicle can travel before its battery must be recharged. Courtesy: Andy Sproles/Oak Ridge National Laboratory, US Department of Energy