The auto industry has begun to cannibalize old car parts for new clean tech purposes, and according to the latest news from the Energy Department it looks like old tires can be gobbled up, digested, and spit out for use in lithium-ion batteries. The new technology could help solve a looming crisis in the lithium-ion battery market as rising demand for electric vehicles threatens to squeeze the supply of critical materials, including graphite as well as lithium.
Go ahead and hold your breath while you wait for the labwork to make it into commercial development, because the agency’s Oak Ridge National Laboratory already has already the wheels in motion to license the new process for EV batteries as well as wind and solar energy storage.
The Lithium-Ion Battery Crisis
Until fuel cell electric vehicles break into the mass market (okay, so don’t hold your breath for that one), the EV field is going to be dominated by batteries, and so far the gold standard for EV batteries has been based on lithium-ion technology.
Lithium-ion batteries have won out in the efficiency department (and they keep getting better), but bringing the cost of the technology down to a competitive level with gasmobiles has been a major challenge.
To help nudge things along, the Obama Administration launched the EV Everywhere Challenge, which aims to make the US the first nation in the world where EVs are just as affordable and convenient as conventional autos.
That explains why taxpayer dollars are going into projects like the new Oak Ridge tire reclamation process. The new technology is aimed squarely at making lithium-ion batteries less costly, and to ice the cake it also makes them more efficient.
Graphite Supply And Li-Ion Batteries
The new technology is also aimed at helping to guarantee a stable, domestic supply of critical materials for lithium-ion technology. Critical Materials also happens to be another Obama Administration taxpayer-funded initiative, so go ahead and give yourself another pat on the back for that one.
The timing is perfect for the Oak Ridge announcement, because the rising demand for EVs has already started to cause a ripple in the commodities market that could exert upward pressure on EV battery prices.
Lithium supply has been grabbing most of the spotlight, but since there is a lot more graphite in lithium-ion batteries than there is lithium, it’s time to catch up.
Graphite is a used widely material in the conventional auto industry supply chain. It also plays a critical role in lithium-ion batteries as a key component of the anode. If you’re guessing that most of the world’s graphite currently comes from China, you’re right, which opens a whole ‘nother can of worms for EVs.
From marketwatch.com, for example, we learn that the planned Tesla Motors Gigafactory alone is expected to “disrupt the car and battery industry for the foreseeable future,” partly by creating a huge spike in global demand for graphite.
Cannibal Cars Solve Global Graphite Crisis
That’s where the new Oak Ridge process comes in. The Oak Ridge team has developed a way to reduce old tires to a modified form of carbon black, which shares similar properties with graphite.
If carbon black from old tires is ringing some bells, the pyrolysis technology behind the process is pretty well established.
What’s new is Oak Ridge’s proprietary pretreatment process. You can find the rundown at RSC Advances under the title “Tailored recovery of carbons from waste tires for enhanced performance as anodes in lithium-ion batteries.”
Basically, the process involves creating a slurry of rubber through a digestion process. The slurry is then dewatered and compressed into a cake before undergoing pyrolysis.
Here’s the rundown from the abstract:
Micronized tire rubber was digested in a hot oleum bath to yield a sulfonated rubber slurry that was then filtered, washed, and compressed into a solid cake. Carbon was recovered from the modified rubber cake by pyrolysis in a nitrogen atmosphere.
The result was a modified form of carbon black with a distinctive microstructure, yielding far greater efficiency than conventional carbon black when applied to the anode of a lithium-ion battery:
Electrochemical studies revealed that the recovered-carbon-based anode had a higher reversible capacity than that of graphite. Anodes made with a sulfonated tire-rubber-derived carbon and a control tire-rubber-derived carbon exhibited an initial coulombic efficiency of 71% and 45%, respectively. The reversible capacity of the cell with the sulfonated tire rubber-derived carbon as the anode was 390 mA h g−1 after 100 cycles, with nearly 100% coulombic efficiency.
According to the research team, the thing about 390 milliamp hours per gram of carbon anode after 100 cycles means that the new form of carbon black “exceeds the best properties of commercial graphite.”
Okay, so that takes care of the graphite supply problem. What’s next?
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