Microwaving to Save Batteries: Revolutionary Cathode Recycling Process Unveiled

Instead of piling up old lithium-ion batteries as waste, researchers at the U.S. Sandia National Laboratories have developed a new process based on a microwave reactor to extract and recreate their cathodes. The breakthrough method not only recycles but upcycles the materials of spent energy storage devices. Significantly faster and more cost-effective than traditional high-temperature processes, this technology could turn discarded batteries into a new, secure domestic source of critical raw materials in the future.

Global Cobalt Dependency and Supply Chain Challenges

Lithium-ion batteries now power almost everything, from smartphones and earbuds to electric vehicles (EVs) and large-scale, grid-integrated energy storage systems. The most expensive and critical component of these batteries is the positive electrode, or cathode (marked with a plus sign on batteries). Manufacturing this component relies heavily on mineral supplies from a limited number of countries, particularly lithium and cobalt. For instance, roughly 70 percent of the world’s cobalt production comes from a single country, the Democratic Republic of the Congo.

Clare Davis-Wheeler Chin, a nanomaterials chemist at Sandia and one of the inventors of the new method, emphasized that cobalt is a critical raw material for almost all modern consumer electronics. Because the supply comes largely from one main source, the global cobalt chain is highly vulnerable. She highlighted that the world will soon face a massive volume of end-of-life electric vehicle batteries.

These will either end up in landfills, or there is an opportunity to “mine” them, thereby establishing a stable domestic raw material supply. Naturally, these energy storage units were not originally designed to be easily disassembled and have their metals recovered at the end of their lifecycle. Therefore, the research team had to invest significant scientific effort into successfully extracting the cathodes and turning them into an industrially usable powder.

Innovation in the Microwave Reactor: 2 Hours Instead of 7 Days

For the chemical process, the research team uses a microwave reactor that is similar in physical size and energy consumption to a standard household microwave oven, but technologically much more advanced and precisely controllable. Inside the reactor, using a large, positively charged ion—whose mechanism, according to the scientists, is similar to the active ingredients found in hair conditioners—they can open up the old cathode powder into tiny, ultra-fine layers called nanosheets.

Davis-Wheeler Chin pointed out the physical characteristic that microwaves are incredibly efficient at heating water. Interestingly, the uneven heat distribution that is often frustrating when heating food at home proves explicitly advantageous in this industrial process for rapidly breaking down cathode materials. The quantitative data recorded during the experiments is spectacular: the microwave process reduced the time needed to convert powdered lithium cobalt oxide—the most common cathode material in old lithium-ion batteries—into nanosheets from the previous seven days to just two hours.

Furthermore, the processing efficiency has improved drastically. While previously used methods could only convert 60 percent of the material into nanosheets, the new Sandia method successfully converts 95 percent of the input material. Kirsten Jones, a former Sandia intern and current doctoral candidate at the University of New Orleans, also actively participated in developing the method.

“Self-Healing” Nanosheets and Chemical Ion Exchange

The new microwave nanosheet process has another massive industrial advantage: during the process, it automatically repairs microscopic defects in the cathode material caused by years of use and charging cycles, and even completely removes impurities. Most existing cathode recycling methods currently in use cannot “heal” these material defects without multiple, costly, and time-consuming additional steps.

During the research project, computer simulations conducted by another scientist, Leung, in the fall of 2022 predicted the theoretical possibility of exchanging metal ions. The researchers subsequently used several different methods to successfully demonstrate that they could replace about one-ninth (1/9) of the cobalt in the material with nickel. Aliya Lapp, an electrochemist at Sandia—who joined the research team in a later phase of the project and provided professional guidance on both ion exchange and the most economical paths for upcycling—explained that the cobalt removed from the nickel-substituted cathode could then be captured and reused in another new cathode.

For this specific capture process, Sandia geochemist Anastasia Ilgen developed an innovative method based on a metal-organic framework that selectively extracts the replaced cobalt from the complex reaction mixture. In practice, this means the process can effectively produce two new cathodes from a single old one.

Economic Potential and Future Industrial Prospects

One of the main challenges in establishing a domestic source of critical minerals is ensuring that cathodes recovered and “upcycled” from old batteries are cheaper on the market than brand new cathodes or cathode materials imported from other countries. Preliminary analyses conducted using an economic modeling tool developed by Argonne National Laboratory show that Sandia’s new method can increase the profitability of cathode recycling by at least 30 percent compared to current state-of-the-art recycling technologies.

Electrochemist Aliya Lapp emphasized that the technology is highly scalable and widely applicable: in the future, the process could be extended to the cathodes of other types of batteries, such as sodium-ion or zinc-ion batteries, provided the cathode material is a layered intercalation compound.

The research team is currently still working on refining the chemical process, including improving the ion exchange mechanism and conducting an even more detailed analysis of the economic return of the approach. The technology has already been protected by two patents, and the laboratory is actively seeking industrial partners for cooperative research agreements, technology licensing, and applications to the Technology Commercialization Fund.

The innovative nature of the process is perfectly illustrated by the fact that the development was nominated for the prestigious R&D 100 Awards. The initial phase of the research was funded by Sandia’s internal Laboratory Directed Research and Development (LDRD) program, while the advancement of the technology’s maturity was supported by the Department of Energy’s (DOE) Energy I-Corps program.

Reference and Source Used:

• Official research institute press release by Sandia National Laboratories, part of the U.S. Department of Energy (DOE): Mining batteries, in a microwave