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Summer 2016

Advancing Batteries: Recharge, Regenerate, Recycle

A simple method for regenerating the cathode, a limiting factor in rechargeable batteries

Michelle A. Harris

Diagram showing the recycling of the cathode in a coin-cell battery. Reproduced from Poyraz et al. (see below) with permission of The Royal Society of Chemistry.

From smart phones to electric cars, rechargeable batteries play a significant role in the world’s energy use. Unfortunately, such batteries do not last forever. The environmental and financial concerns of battery disposal have sparked research into prolonging their overall lifespan. One of the major limiting factors for rechargeable batteries is the degradation of the cathode. The Center for Mesoscale Transport Properties (m2M), an Energy Frontier Research Center, has demonstrated the most efficient cathode recycling in batteries.

When looking at a common battery, the cathode is the part labeled “+”. Over several cycles of recharging, the cathode loses capacity and holds less voltage. In lithium-based cathodes, this is typically caused by the loss of free lithium—leading to overcharging of the cathode. Overcharging the cathode contributes to structural defects and irreversible changes to the physical properties of the material.

Current methods for recycling the cathode are complicated processes that can involve hazardous acids and bases or completely destroying and remaking the cathode. Heat treatment is a less-destructive method for recycling the cathode but an effective method has not been found for common lithium-based cathodes because of their composition. Center director Esther Takeuchi and the research team at m2M developed a simple method for recycling a manganese oxide-based cathode using heat.

Their method for regenerating the manganese oxide-based cathode requires only two steps. First, they washed the cathode with dimethyl carbonate, a green chemistry solvent. Next, they heat the cathode at 300 ºC for two hours in open air. The presence of ambient air is a crucial detail. Why? Over several uses, the manganese oxide-based cathode loses oxygen and degrades structurally. Heat treatment in air restores the oxygen and restores the structure, or crystallinity.

The key to the manganese oxide cathode developed by m2M is its self-supporting structure where it can be separated from the battery, regenerated, and replaced (see figure). The battery used the manganese oxide cathode and a lithium metal anode. After discharging and recharging 50 times, the cathode was removed, heat treated, and replaced. They saw no degeneration of the battery after regenerating the cathode four times. This allowed the battery to last for more than 200 cycles.

After such positive results, the research team at m2M is hopeful that this method provides a conceptual approach that can be used more broadly. Takeuchi describes the research as “a new way of thinking about recycling batteries where an entire electrode can be regenerated and reused. We hope our results inspire further advances in this field.”

The m2M center’s method for recycling the cathode will lead to less battery waste and alleviate the cost of frequently replacing the battery. Their findings on the regeneration of the manganese oxide cathode shed light on regeneration for lithium and other metal cathodes and anodes as well. These results from m2M are revolutionary for the future of research and development of rechargeable batteries.

Acknowledgments

This work was supported as part of the Center for Mesoscale Transport Properties, an Energy Frontier Research Center supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. The transmission electron microscopy work was supported by DOE, Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering. The X-ray photoelectron spectroscopy measurements used resources of the Center for Functional Nanomaterials, a DOE Office of Science user facility, at Brookhaven National Lab.

More Information

Poyraz AS, J Huang, S Cheng, DC Bock, L Wu, Y Zhu, AC Marschilok, KJ Takeuchi, and ES Takeuchi. 2016. “Effective Recycling of Manganese Oxide Cathodes for Lithium Based Batteries.” Green Chemistry 18:3414-3421. DOI: 10.1039/C6GC00438E

About the author(s):

  • Michelle A. Harris is a postdoctoral researcher in the Argonne-Northwestern Solar Energy Research (ANSER) Center at Northwestern University under Michael Wasielewski. Her research involves ultrafast spectroscopic studies of charge transfer in DNA hairpins and in donor-acceptor molecules for solar fuels applications. She received her B.S. in integrative biology from the University of Illinois at Urbana-Champaign in 2009. She did her dissertation research under Dewey Holten in the Photosynthetic Antenna Research Center (PARC) and received her Ph.D. in chemistry from Washington University in St. Louis in 2014.

Heating Up Battery Recycling

New technique could change how long rechargeable batteries last

A new approach recycles a battery’s cathode. On the left, a microscopic image of the electrode before charging. On the right, after recycling. Modified by Cortland Johnson, Pacific Northwest National Lab, from Poyraz et al. (see below) with permission of The Royal Society of Chemistry.

Whether they’re in your cell phone or your wireless keyboard, you know that the battery will fail, and that failure has economic and environmental costs. Often the problem is the failure of the cathode (electrode labeled with the + sign). Scientists from Center for Mesoscale Transport Properties (m2M) Energy Frontier Research Center demonstrated—for the first time—an efficient way to make manganese cathodes work again. Their recycling approach led to good results, with the battery charging and discharging 200 times without the cathode degrading. Eventually, this heat treatment could lead to less waste and lower costs. The m2M center is led by Stony Brook University.

More Information

Poyraz AS, J Huang, S Cheng, DC Bock, L Wu, Y Zhu, AC Marschilok, KJ Takeuchi, and ES Takeuchi. 2016. “Effective Recycling of Manganese Oxide Cathodes for Lithium Based Batteries.” Green Chemistry 18:3414-3421. DOI: 10.1039/C6GC00438E

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.