How to Turn Tires Into Batteries for Electric Cars

A new method converts scrap tire rubber into porous carbon that works better than graphite as a Li-ion battery anode

2 min read
How to Turn Tires Into Batteries for Electric Cars
Photo: iStockphoto

Scrapped car tires have been used for construction material and recycled into floor mats and shoe soles. Now they might find their way back into hybrid and electric cars, but under the hood. Scientists at Oak Ridge National Laboratory have devised a method to convert tire rubber into a carbon material for lithium-ion battery anodes.

Conventional lithium anodes are made of the graphite, a natural carbon material that is mined. The Oak Ridge researchers, led by materials chemist Parans Paranthaman, have found an alternative waste source for the carbon anode.

In a paper published online in the journal RSC Advances, they outlined a straightforward process to convert waste tire rubber into nanoporous carbon. They first pulverize waste tire rubber into tiny micrometer-sized pieces, which they break down in a hot sulfuric acid bath. The resulting rubber slurry is filtered, washed and turned into a solid cake. Heating the cake in the presence of nitrogen gives a highly porous carbon black material with pores that were less than 2nm in diameter.

The researchers made a small, lab-scale battery using the carbon material as the anode. The anode’s capacity — a measure of the charge it can store per gram of weight — was 390 milliamp-hours per gram (mAh/g). That’s slightly better than graphite’s 370 mAh/g capacity.

The tire rubber-derived carbon maintained that capacity after 100 charge-discharge cycles. But the recycled anodes will need to prove their mettle for the thousands of charge cycles that real-world batteries undergo.

Plus, they will have to compete with several other high-capacity anode materials that researchers are tinkering with in attempts to make longer range, longer-lasting Li-ion batteries. There is, for instance, a big research push to replace graphite anodes with nanostructured silicon, which take advantage of silicon’s 4000 mAh/g Li-storage capacity. Graphene is also a strong contender for Li-ion anodes. Meanwhile, some efforts are focused on making both the anode and cathode with carbon nanomaterials, in one case derived from cotton fibers.

For now, though, graphite is the anode material-of-choice. And the new technique offers an inexpensive, environmentally friendly way to make an anode material that’s better than graphite. “Using waste tires for products such as energy storage is very attractive not only from the carbon materials recovery perspective but also for controlling environmental hazards caused by waste tire stock piles,” Paranthaman said in a news release.

The Conversation (0)

Smokey the AI

Smart image analysis algorithms, fed by cameras carried by drones and ground vehicles, can help power companies prevent forest fires

7 min read
Smokey the AI

The 2021 Dixie Fire in northern California is suspected of being caused by Pacific Gas & Electric's equipment. The fire is the second-largest in California history.

Robyn Beck/AFP/Getty Images

The 2020 fire season in the United States was the worst in at least 70 years, with some 4 million hectares burned on the west coast alone. These West Coast fires killed at least 37 people, destroyed hundreds of structures, caused nearly US $20 billion in damage, and filled the air with smoke that threatened the health of millions of people. And this was on top of a 2018 fire season that burned more than 700,000 hectares of land in California, and a 2019-to-2020 wildfire season in Australia that torched nearly 18 million hectares.

While some of these fires started from human carelessness—or arson—far too many were sparked and spread by the electrical power infrastructure and power lines. The California Department of Forestry and Fire Protection (Cal Fire) calculates that nearly 100,000 burned hectares of those 2018 California fires were the fault of the electric power infrastructure, including the devastating Camp Fire, which wiped out most of the town of Paradise. And in July of this year, Pacific Gas & Electric indicated that blown fuses on one of its utility poles may have sparked the Dixie Fire, which burned nearly 400,000 hectares.

Until these recent disasters, most people, even those living in vulnerable areas, didn't give much thought to the fire risk from the electrical infrastructure. Power companies trim trees and inspect lines on a regular—if not particularly frequent—basis.

However, the frequency of these inspections has changed little over the years, even though climate change is causing drier and hotter weather conditions that lead up to more intense wildfires. In addition, many key electrical components are beyond their shelf lives, including insulators, transformers, arrestors, and splices that are more than 40 years old. Many transmission towers, most built for a 40-year lifespan, are entering their final decade.

Keep Reading ↓ Show less