Ensuring the supply of critical materials

Our society’s ability to transition to clean energy technologies depends, to a great extent, on having adequate supplies of the materials needed to manufacture components that will be ubiquitous in a clean energy economy — particularly batteries and electric motors.

Diversifying supply

One way that ORNL helps to ensure adequate supplies of these materials is through its participation in the Critical Materials Institute, one of DOE’s Energy Innovation Hubs, led by Ames Laboratory. ORNL Corporate Fellow Bruce Moyer, who heads CMI’s Diversifying Supply Focus Area, noted that the laboratory has made significant advances in this field.

Among these critical materials are rare-earth metals, a group of 17 elements used in technological applications such as magnets. Unfortunately, their concentrations in nature don’t match our demand for them.

“In the most common ore, just two rare earths account for 75 percent of the amount of rare earths present, cerium and lanthanum,” Moyer said. “The rare earth that we need the most is neodymium, and it makes up about 15 percent. So we have to mine five times as much cerium and lanthanum to supply the neodymium that we need for magnets.”

One solution to this imbalance is to find new uses for these overabundant metals, increasing both their value and the profitability of mining them.

“So we came up with the idea to look for unique uses for cerium in aluminum alloys,” Moyer explained. “This was an idea that former ORNL staff scientist Orlando Rios brought to us with a partner from ECK Industries.”

They proposed developing a new aluminum–cerium alloy for transportation applications, which last year consumed over 1 million metric tons of aluminum in the United States. Meeting part of that demand with an aluminum–cerium alloy could significantly increase demand for cerium.

“A strong demand for cerium means that rare-earth mines producing neodymium could increase their revenue streams by hundreds of millions of dollars per year,” Moyer said. “That would increase their profitability and competitiveness.”

ECK wanted to know whether this alloy is castable, so CMI funded a project to research this question. Rios’s team, with ECK as partner, found that the alloy would be as castable as the best aluminum alloys on the market and that some formulations didn’t need any heat treatment at all.

“If you can avoid heat treatment, you can cast a part and use it almost as it comes out of the mold,” Moyer said.

The new alloy proved useful to Emrgy Inc., which specializes in small-scale hydroelectric power for municipalities and agricultural irrigation. The company found that the alloy worked well in hydroelectric turbine blades and began putting the new blades in the field within about three years.

“I’ve never seen an example of where something has been turned around so fast from an early-stage research idea to a product produced by industry,” Moyer said.

Mining motors and batteries

ORNL senior research scientist Tim McIntyre heads the laboratory’s rare-earth recovery and reuse efforts, specializing in deconstructing discarded consumer products to retrieve the critical materials they contain. Recent projects have included harvesting magnets from computer hard drives and electric motors as well as extracting critical materials from electric vehicle batteries.

“In the case of hard drives, we’re recovering nickel-plated neodymium-iron-boron magnets,” McIntyre said. “Thanks to the nickel coating, these magnets are usually in pristine condition and are easy to remove. We’re also chasing magnets in larger electric motors, but since these magnets don’t have a protective coating, it’s more challenging to remove them intact. As a result, we end up with powders and chunks of magnet material.”

Material retrieved by these processes can be crushed and remanufactured for new magnet applications.

“When we recycle electric vehicle batteries, we break them down to individual cathodes, anodes and separation membranes,” McIntyre said. “That’s where we find the lithium, nickel, cobalt and manganese — key materials for lithium-ion battery production.”

McIntyre said a big challenge in making recycling cost-effective is the logistics of processing recycled materials in large quantities. As a result, his team focused on developing high-throughput technology. Despite variations in battery construction from manufacturer to manufacturer, McIntyre and his team successfully demonstrated an automation capable of processing 10 million hard drives per year.

The Li-ion battery processing facility at ORNL’s National Transportation Research Center recovers battery cathodes and ships them to industrial partners that extract the lithium, cobalt, nickel and manganese for use in new batteries.

Recovering battery materials from electronic waste

ORNL is also exploring novel ways to increase the recovery of critical materials from e-waste. Ramesh Bhave, ORNL distinguished research scientist and project leader for membrane-based battery materials and rare-earth elements separations, noted that sometimes recycled battery material isn’t thoroughly separated.

“You end up getting material that contains everything — cathodes, anodes and other elements from the battery,” Bhave said.

“We take this material and dissolve it in an acid solution, and whatever is not dissolved is filtered out. That leaves primarily lithium, cobalt, manganese and nickel. Then we use our Membrane Solvent Extraction — or MSX — technology, which first selectively extracts each of these elements. Then, on the other side of the module, each element is back-extracted into another dilute solution of acid or other suitable media. From there, the materials are recovered.”

All of the elements are recovered, and the process produces recycled materials that are more than 99.9% pure — pure enough to be used to produce new batteries.

“This turns end-of-life scrap material into materials that can be used again in the battery manufacturing process,” Bhave said. “Also, the process is scalable. These membrane modules can be arranged to handle 1,000 tons per year of production capacity.”

ORNL has licensed MSX technology and other similar separation technologies to Momentum Technologies, Inc., so the company can explore its potential for recovering critical materials from batteries, magnets and other devices.

Direct conversion: helping to close the recycling gap

Ilias Belharouak is an ORNL distinguished scientist and head of the Electrification and Energy Infrastructure section of the laboratory's Energy and Transportation Sciences Division. He’s also deeply involved in developing practical ways to recycle lithium-ion batteries — like those that are used in electric vehicles.

Traditional gas-powered vehicles use lead-acid batteries, 90 percent of which are recycled. That figure is a goal of sorts for Belharouak.

“Compare that 90 percent to the figure for lithium-ion battery recycling,” Belharouak said, “which is in the 5 to 10 percent range. That is a huge gap, and it will take years to close it. The issue truly is technology. The technology to recycle materials from lithium-ion batteries efficiently, cost-effectively and in an environmentally friendly manner does not currently exist.”

Belharouak noted that this situation poses a growing challenge for battery manufacturers’ supply chains.

“If you have an electric vehicle," he said, "after about 10 years, you will have a battery that contains more than 200 kilograms of material that is ready to be recycled. If you don't have the technology to recycle batteries, that creates a supply chain issue. To keep making batteries for EVs, battery manufacturers need to have access to streams of raw materials — minerals and other materials. However, if you have the technology to recycle lithium-ion batteries, that takes some of the pressure off supply chains.

“At a high level, that's what lithium-ion battery recycling is all about.”

The third way

Currently, the state of the art for lithium-ion battery recycling consists of two main processes: pyrometallurgical and hydrometallurgical. The pyrometallurgical process involves burning lithium-ion cells and then using chemistry to separate the desirable elements from the resulting slag. The hydrometallurgical process focuses on chemically dissolving batteries and then separating specific elements from the resulting solution.

“Our process provides a third way,” Belharouak said. “It’s what we call direct recycling. Unlike the other recycling processes, we're recovering the components of the batteries without reducing them to their individual elements.”

The direct recycling effort is headquartered at the ReCell Advanced Battery Recycling Center at Argonne National Laboratory. ReCell is a collaboration among Argonne, the National Renewable Energy Laboratory, ORNL, Michigan Technological University, the University of California San Diego, and Worcester Polytechnic Institute. The center's goal is to develop cost-effective, flexible processes for recycling lithium-ion batteries.

The logic behind direct recycling is that, since the battery manufacturer has already paid to process battery materials from scratch, it makes sense to develop a way to recycle battery components without having to process the materials again.

For example, one aspect of direct recycling involves using uses triethyl phosphate, a “green” solvent, to separate battery cathodes from metal foil current collectors. These and other recovered components can be reused in new batteries. Currently the direct recycling process recovers battery anodes, cathodes, separators, electrolytes and related hardware.

“This saves both time and money,” Belharouak said, “and it delivers benefits in terms of environmental costs as well.

“At the national laboratories, we do the R&D to develop effective processes, and then we scale-up those processes to the point where our industrial partners can take them to the next level. The ReCell center has industrial partners who bring this sort of expertise from all points along the battery supply chain.

“That sort of collaborative R&D is the way to gain ground in this field. Recycling lithium-ion batteries is an R&D problem, and R&D is going to find the solution.”