June 7 (UPI) — Undermined by a handful of high-profile accidents, self-driving vehicles remain very much a work-in-progress, but some researchers are already turning their attention to the skies, hoping to make the world of the Jetsons a reality.
In a new paper, published Monday in the journal Joule, engineers at Penn State have published plans for a battery prototype capable of powering flying cars.
“I think flying cars have the potential to eliminate a lot of time and increase productivity and open the sky corridors to transportation,” lead study author Chao-Yang Wang said in a press release.
“But electric vertical takeoff and landing vehicles are very challenging technology for the batteries,” said Wang, director of the Electrochemical Engine Center at Penn State.
In their paper, Wang and his research partners established a variety of technical requirements for the batteries of electric vertical takeoff and landing vehicles, or eVTOLs.
In order to get a flying car off the ground, an electric battery must be able to deliver a lot of power and fast.
“Batteries for flying cars need very high energy density so that you can stay in the air,” said Wang. “And they also need very high power during take-off and landing. It requires a lot of power to go vertically up and down.”
Additionally, a flying car battery must ideally be able to be quickly recharged. Unlike most flying vehicles, eVTOLs will likely be taking off and landing rather frequently.
“Commercially, I would expect these vehicles to make 15 trips, twice a day during rush hour to justify the cost of the vehicles,” said Wang. “The first use will probably be from a city to an airport carrying three to four people about 50 miles.”
In the lab, researchers tested the performance of a pair of energy-dense lithium-ion batteries capable of delivering the kind of power needed to sustain a 50-mile, five-to-ten-minute eVTOL trip.
The experiments showed the batteries were good for 2,000 fast-charges over the course of their lifetimes.
Tests involving batteries the team is developing for electric road vehicles showed heat is key to preventing lithium spikes, which can damage batteries and lead to dangerous battery failures.
To avoid this, Wang and his colleagues were able to rapidly heat the batteries by incorporating nickel foil into the design.
Researchers found suitable heating also allowed the batteries to deliver a rapid burst of power — the type of discharge required for takeoffs and landings — more efficiently.
“Under normal circumstances, the three attributes necessary for an eVTOL battery work against each other,” said Wang. “High energy density reduces fast charging and fast charging usually reduces the number of possible recharge cycles. But we are able to do all three in a single battery.”
It’s easy to rapidly charge a battery that’s nearly drained, but frequent takeoffs and landings will require rapid charging of half-full batteries — a more difficult task. However, the latest research suggests sufficient heating can solve this problem too.
“I hope that the work we have done in this paper will give people a solid idea that we don’t need another 20 years to finally get these vehicles,” said Wang. “I believe we have demonstrated that the eVTOL is commercially viable.”