Hybrid battery research gets international attention

CLEMSON, SC — Hybrid car owners may take great mileage for granted, but the cars’ batteries eventually wear out and need to be replaced, usually at a cost of several thousand dollars.

The research that Simona Onori does at Clemson University can help those batteries last longer and could help find new ways to reuse them once they retire from the road.

Onori, an assistant professor in the automotive engineering department, literally has been traveling the world to share what she has learned so far.

Next up is an invitation from the Beijing Institute of Technology. The weeklong trip starts May 30 and is expected to strengthen ties between Clemson and China, the most populous country in the world.

“They want to learn about the design methods we have developed,” she said. “They want to use our techniques on their new-generation vehicles. Hopefully, this will open up opportunities to collaborate with Beijing and create a partnership between the two universities.”

Onori develops algorithms that help hybrid cars decide when they should run on gas and when they should draw energy from the batteries. Relying too heavily on the batteries will quickly wear them out, so it can be a delicate balance, she said.

Warranties on car batteries usually last eight to 10 years. Replacing batteries costs about $3,000 for the most popular models. It’s not a home-repair job for most drivers. Improper handling of hybrid-vehicle batteries can lead to electrocution.

Then there are questions about how to keep worn-down batteries from going to waste. Onori said batteries could be repurposed when they are retired from the road.

“Most such lithium-ion batteries are still viable for use in stationary applications,” Onori said.

Zoran Filipi, chair of automotive engineering, said that Onori’s exemplary work makes her an excellent ambassador for Clemson University.

“Simona is a fast-rising expert in her field,” he said. “Her work has been published in several respected journals, and she is a valued member of the team in the department of automotive engineering. It’s easy to see why she is in such high demand worldwide.”

Onori also heads to the University of Stuttgart in Germany in June to teach at the Stuttgart International Summer School-Mobility. Last November, she gave a series of seminars at the University of Trento in Italy, and in December she was an invited speaker at Chalmers University of Technology in Göteborg, Sweden.

In recent years, Onori has sharpened her focus on lithium-ion batteries, a relatively new technology for hybrid cars.

When hybrid cars first became widely available to the public in 1997, they had nickel metal hydride batteries. But automakers in recent years began switching over to lithium-ion batteries, which are lighter and can hold a charge longer. Most new hybrid cars carry lithium-ion batteries.

Onori has been putting them to test in the Battery Aging and Characterization Lab at the Clemson University International Center for Automotive Research.

Each hybrid car has a battery pack that contains hundreds of battery cells, each of which looks like an oversized AA battery. Onori puts those battery cells in a device called a Peltier Junction that allows her to control the temperature as she charges and discharges the cell.

In so doing, she can simulate how a battery would perform in any environment from the desert to the tundra.

Her experiments are opening new insights into how batteries degrade when used in hybrid, plug-in hybrid and electric vehicles. With the data, she works to improve vehicle efficiency and mileage.

“My research aims at the development of algorithms to better utilize batteries in hybrid and electric vehicles, ” Onori said.