Researchers have developed a new electrolyte to address the challenges of “stressed out” lithium-ion batteries, which could give them second lives in less strenuous applications.
Lithium-ion batteries (LiBs) have exploded in popularity thanks to their ability to pack a large amount of power in a relatively small and light package. But they aren’t perfect, especially when a lot of that power needs to be drawn from the battery cell in a short amount of time. Drones are a perfect example—much needed power for takeoff puts high strain on the batteries.
Working to correct this issue, researchers from Oak Ridge National Laboratory manufactured a set of LiB cells containing a specially designed, fast-charging and discharging electrolyte. Then, they drained 15 times the battery’s optimal capacity for 45 seconds. This process simulated the rapid, high-power draw, also known as a discharge, needed during vertical takeoff. After the initial discharge pulse, the cells were further drained at a more normal discharge rate and then recharged. The team found that none of the tested cells lasted more than 100 cycles under these high-stress conditions, with most starting to show decreased performance around 85 cycles.
After being “stressed,” the researchers subjected the LiB cells to a more normal, lower rate power draw. In this experiment, they observed that the cells partially retained their capacities under low-rate conditions, but failed quickly when put under rapid current drain conditions again.
These results indicate that the LiBs typically used in drones might not have the characteristics necessary for long-term, high-stress usages, but they could be retired and meet more typical power demands in other applications, such as battery back-ups for power supplies and energy-grid storage.