As our everyday lives become ever more dependent on battery technology – specifically the lithium-ion batteries (LIBs) that power our smartphones, laptop computers, electric vehicles, and other portable gadgets – the quest to build ever more efficient and economical batteries has only intensified. It's more than simply a matter of science and engineering, however: LIBs are dependent on materials such as cobalt (Co) that are not only expensive and in high demand but are fraught with environmental and humanitarian issues. 

Another cathode material, nickel (Ni), is rapidly becoming a new "pain point" for battery makers. But functional alternatives to cobalt and nickel result in markedly decreased battery performance and reliability. Researchers at University of California, Irvine, as well as the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Brookhaven National Laboratory, have demonstrated a new approach to achieving viable Co-free, low-Ni battery cathodes using a method called complex concentrated doping. The work appeared in Nature Energy.

Battery makers have long been trying to find alternatives to cobalt. One previous strategy in low- to medium-Ni ternary cathodes has been to substitute cobalt with a material such as manganese (Mn), but this greatly shortens the cathode's cycling life. Nickel has also become a concern fairly recently as its price steadily rises amid increasing unease over environmental risks in its production. With all these issues in mind, the current investigators sought to create an cathode active material without any cobalt and as little nickel as possible through doping an NMC-532 material (a nickel-manganese-cobalt material commonly used in cathodes) with elements that can chemically substitute for the functions of cobalt.

Using an ingenious recipe of manganese, titanium, magnesium, niobium and molybdenum, a combination of ingredients designed to take the place of cobalt, the researchers created a new layered cathode. The new material was evaluated and compared with NMC-532 in both half-cell and full-cell configurations using a variety of techniques, including cycling, capacity, and retention tests; thermal stability studies with transmission electron microscopy; and X-ray studies of structural properties at beamlines 20-BM-B and 17-BM of the Advanced Photon Source, a DOE Office of Science user facility at Argonne.

These demonstrated that the HE-N50 cathode shows a high specific energy of greater than 700 Watt-hours per kilogram – much higher thermal stability compared to NMC-532 and other similar cathodes – 

plus high capacity and long battery lifecycles. The low cation mixing of this particular cathode formulation also increases the efficiency of the nickel component, which means that 50 percent less nickel is required for a working battery. Eliminating cobalt by replacing it with cheaper materials such as manganese also significantly reduces battery costs. 

The work provides a compelling demonstration of the possibilities of the complex concentrated doping strategy in battery design. It offers the prospect of the specific tailoring of lithium-ion batteries to meet particularly desired operational requirements such as longevity, capacity, or thermal stability, while also taking into account the economic, political, and social considerations involved with commonly-used battery materials. Some LIBs, such as laptop batteries, need to be small, lightweight and easily rechargeable; others need large capacities, such as in electric vehicles; still others used for long-term stationary storage require longevity and resistance to changing environmental conditions. The complex concentrated doping technique promises the least expensive and most efficient battery "recipe" for the job at hand.

The investigators plan to continue developing and expanding this doping strategy to meet the ever-increasing demand for better and cheaper battery technology.  In a world trying to balance social and environmental dilemmas with the ever-growing demands of advanced technology, such creative solutions will become increasingly essential. – Mark Wolverton

See: R. Zhang¹, C. Wang¹, P. Zou¹, R. Lin², L. Ma²,  T. Li³, I-H. Hwang³, W. Xu³, C. Sun³, S. Trask³, H.L. Xin¹, “Long-life lithium-ion batteries realized by low-Ni, Co-free cathode chemistry” Nat Energy 8, 695-702 (2023)

Author affiliations: ¹University of California Irvine; ²Brookhaven National Laboratory; ³Argonne National Laboratory

This work is primarily supported by the US Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy under the award number DEEE0008444. R.Z.’s work done for this study was funded by H.L.X.’s start-up funding. This research used resources of the Center for Functional Nanomaterials and 7-BM beamlines of the National Synchrotron Light Source II, which are two US DOE Office of Science User Facilities operated for the DOE Office of Science by Brookhaven National Laboratory under contract number DE-SC0012704. This research used resources from the Advanced Photon Source, a US DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract number DE-AC02-06CH11357. R.L. was supported by the Assistant Secretary for EERE, Vehicle Technology Office of the US DOE through the Advanced Battery Materials Research (BMR) Program, under contract no. DE-SC0012704. We acknowledge the use of facilities and instrumentation at the University of California, Irvine Materials Research Institute (IMRI), which is supported in part by the National Science Foundation through the University of California, Irvine Materials Research Science and Engineering Center (DMR-2011967). We also acknowledge the electrode produced at the US DOE CAMP (Cell Analysis, Modeling and Prototyping) Facility, Argonne National Laboratory. The CAMP Facility is fully supported by the DOE Vehicle Technologies Office.

The U.S. Department of Energy's APS at Argonne National Laboratory is one of the world’s most productive x-ray light source facilities. Each year, the APS provides high-brightness x-ray beams to a diverse community of more than 5,000 researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. Researchers using the APS produce over 2,000 publications each year detailing impactful discoveries and solve more vital biological protein structures than users of any other x-ray light source research facility. APS x-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC, for the U.S. DOE Office of Science.

The U.S. Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.