With electric aviation still in its infancy, eVTOL developers have largely been relying on the same lithium-ion battery cells found in electric ground vehicles (EVs) to power their aircraft. Although the performance of lithium-ion batteries in EVs is well understood, their application in the aviation industry is relatively uncharted, and it’s not yet clear how these batteries will withstand the harsh conditions they will endure during eVTOL air taxi operations.

To gain a better understanding, researchers at Oak Ridge National Laboratory (ORNL) in Tennessee conducted a study into the effects that an eVTOL aircraft’s flight profile will have on EV batteries after repeated cycling, simulating typical air taxi operations. The research team found that the power and performance demands for eVTOL flight reduce battery performance and longevity, which could potentially pose a safety threat. It could also increase the cost of aircraft maintenance, as batteries will need frequent replacing.

When eVTOLs take off vertically, “the amount of peril that these batteries can experience is going to be like nothing we’ve seen before,” Ilias Belharouak, an ORNL corporate fellow who participated in the study, told AIN. Because eVTOL batteries will be subject to “very harsh conditions,” he explained, they may be prone to premature and unforeseen damage and corrosion.

Belharouak and his team aim to mitigate this problem by advancing lithium-ion battery technology and optimizing battery cells for eVTOL flights. But to find the best solutions, they first needed to thoroughly define the problem. With this study, the team sought to determine exactly what happens to the batteries at a sub-cell level when subjected to the high power demands of eVTOL flights with repeated cycling. The findings will help to inform their search for new materials, particularly for the cell’s electrolytes, which could lead to better performance and endurance.