Sales of such electric vehicles as the Toyota Prius, Nissan Leaf, and Chevy Volt are on the rise, and so, too, is the need for a comprehensive recycling strategy once their batteries wear out. The rechargeable batteries used in electric vehicles (EVs) and hybrid electric vehicles (HEVs) are expected to last eight to 10 years, after which they must be replaced. But there is still an open question about what to do with these partially spent batteries once the time comes.
By the early 2020s, market analysts at Frost & Sullivan foresee the number of used EV batteries reaching 500,000. The jury is still out on the best fate for these petered-out packs — reuse them for other purposes right away, or recycle them immediately to extract valuable materials for use in new batteries?
Scientists worldwide, including those at Argonne National Laboratory's Center for Transportation Research, are exploring various options for recycling batteries, including the latest generation of lithium-based cells in the current generation of EVs. Recycling, however, is not about the lithium. Lithium itself is abundant, in contrast to the nickel and cobalt used in earlier generations of EV and HEV batteries. According to Frost & Sullivan, it costs more to recycle lithium than to mine it. Beyond the lithium, more valuable materials such as cobalt, nickel, and some rare earths such as neodymium can be recovered during the battery recycling process, making it an economically attractive idea.
For now, automakers are taking different approaches to handling spent batteries. Toyota is shipping some of its used Prius batteries to Japan for treatment at a recycling center. General Motors and Nissan are forging arrangements with power companies to reuse old batteries as, for example, storage for wind or solar energy generated during peak hours, or for use as backup power supplies. That's because even when the automotive battery packs are too weak for automotive use, they still can hold up to 80% of their charge. So it makes sense to use them for other purposes and only send them off to a recycling facility as a last stop.
Says Dr. Linda Gaines, an analyst at Argonne working on battery recycling issues, “Getting as much use as possible out of these batteries before recycling them is a great strategy, but what happens in practice will be decided by the economics of different scenarios.”
The DoE has granted $9.5 million to recycling specialist Toxco Inc. to build an advanced lithium battery recycling facility in Lancaster, Ohio. The plant is expected to begin operations later this year and will support the battery recycling infrastructure required by the growth of EV sales in the U.S.
“The new plant will let us continue to recover resources, such as nickel and cobalt, for use in manufacturing new batteries for the U.S. market,” says Ed Green, VP of Toxco's Ohio operations.
So far, Toxco is the only facility in North America able to recycle both primary and secondary lithium batteries. The company's existing lithium battery recycling plant sits in Canada (Trail, B.C.). The Ohio location now processes lead acid batteries, as well as the nickel metal hydride batteries used in the current generation of HEVs. Once the expanded facility is operating, an undisclosed process will separate and isolate constituents from Ni-MH and Li-ion batteries, recycling the materials into battery-ready rare earths, nickel, anode materials such as LiCoO2, LiFePO4 cathode material, and electrolyte.
Company officials note that it is too soon to predict the value recyclers will gain from processing lithium-ion vehicle batteries because automakers are extremely secretive and protective about specific battery formulations. On that topic, Gaines describes what would be the ideal situation — being able to dissect the entire battery, clean and purify the materials, and then recycle them into battery-grade products. A careful recycling program like this would drastically cut down on raw material use and could potentially help make the U.S. self-sufficient in EV battery production.
On that score, there is no shortage of lithium. The latest figures from the U.S. Geological Survey indicate that the known lithium reserves could meet worldwide demand through 2050, even under a high demand scenario.
However, battery makers could see a cobalt supply shortage, depending on the particular battery chemistry adopted most widely by automakers. In the most recent Argonne study, researchers looked at four promising lithium-ion battery types: NCA Graphite, LFP (phosphate) Graphite, MS (spinel) Graphite, and MS TiO. All have lithium in their cathodes, while one uses lithium in its anode as well. Knowing the ingredients of each battery pack would go a long way toward recycling the packs in the right way, so that recycling processes can produce a high-value product. According to Gaines, a Society of Automotive Engineers (SAE) working group is tackling the issue of labeling requirements, so recyclers can sort and process used batteries correctly.
But the best battery chemistry has yet to be determined, and automakers use proprietary formulas for their battery chemistry that are kept tightly under wraps. Accordingly, much work remains to be done in the area of optimizing the output of the recycling process.
Another issue is the recycling process itself: Not all processes are created equal. Which is best depends on a number of factors, says Gaines. The “greenest” process may not be the most economical, because the economics of processing depend on the value of the material recovered. Recycling methods must be compared with one another using several criteria, including environmental impacts, energy savings, how well they alleviate material supply shortages, their economics, regulatory compliance issues, feed requirements, and the usefulness of the end products.
Economics is, not surprisingly, a key factor in Li-ion battery recycling. Although the value of the elements in these batteries may be low, the value of the active materials is high. The objective is to recover the highest-value product possible. For example, with a cathode chemistry of LiCoO2, the value of the constituent materials is $9.90/lb, while the price of the cathode is about $12/lb. In contrast, the value of constituent materials from a cathode chemistry of LiFePO4 drops to around 75 cents/lb, while the price of the cathode remains high at almost $10/lb. In addition, recycling the “rest-of-battery” (components like steel cases and copper wiring) helps the economics make sense. Although the U.S. does not oversee Li-ion battery recycling yet, Europe is further ahead with its regulations: As of September 26, 2011, 50% of cell materials there must be recycled. The “rest of the battery” is included in the 95% automotive recycling requirement. Further, the legal responsibility for recycling belongs to the company making the consumer product.
With regard to specific recycling processes, smelting is one technique now in use in Europe. The smelting process can accept any input in high volume. Whole batteries are fed into the smelter, and a molten mix of cobalt, nickel, and copper comes out at the end. These valuable materials can be sent to refineries for use in new batteries.
As one example of the benefits, recycling saves 70% of the cobalt production energy and related sulfur emissions. Lithium and aluminum are lost to slag, but may find a second life in concrete production. In this scenario, cobalt recovery is the chief economic driver. However, use of other cathode materials would likely reduce the financial incentive to recycle these batteries. Copper and nickel would still be recovered, but the recycler probably would want to be paid to accept the batteries. Li, Al, Mn, and Ti from titanate anodes would go to slag, with materials recovered through additional processes — if the value is high enough to justify it.
A new process still under development called “Eco-Bat” can actually recover battery-grade cathode and anode materials, and even the electrolyte. Researchers have demonstrated they can make new batteries from this process that perform well. If battery-grade materials are recovered, their value could provide an economic incentive to recycle batteries containing no cobalt. However, the mixed-chemistry input would reduce the utility of the product, so pre-sorting might be required. Further, the material being recovered would represent a chemistry that was current 10 to 15 years earlier. It is not clear that there would still be a market for it. As this discussion shows, many questions remain unanswered regarding the reuse and recycling options for electric vehicle batteries.
Standard battery configurations enable efficient recycling equipment design
Battery chemistry standardization reduces need for sorting
Battery pack labeling enables sorting
Design for disassembly enables material separation
SAE working group now discussing battery recycling issues
Argonne National Laboratory, www.anl.gov
Toxco Inc., www.toxco.com