Oak Ridge National Laboratory (ORNL) researchers have developed a new family of cobalt-free cathodes with the potential to replace the cobalt-based cathodes typically found in today’s lithium-ion batteries that power electric vehicles and consumer electronics.

Called NFA—for nickel, iron and aluminum—the new class is a derivative of lithium nickelate and can be used to make lithium-ion battery cathodes. These novel cathodes are designed to be fast-charging, energy-dense, cost-effective, and longer-lasting. Papers on the work are published in Advanced Materials and the Journal of Power Sources.

Electrochemical performance evaluations revealed that our cobalt-free material delivers high capacity of 190 mAh/g at 0.1C. Rate and cycling performance evaluations also indicated good rate capability and cycling stability with 88% capacity retention after 100 cycles at C/3. Using NFA cathodes, we also fabricated a 0.5Ah (C/3) cobalt-free Li-ion battery which demonstrated reasonable cycling stability with ~72% capacity retained after 200 cycles. Overall, our work demonstrates the immense potential of the cobalt-free NFA class cathodes as viable candidates towards development of next generation cost effective lithium-ion batteries.

—Muralidharan et al. (2020b)

According to Ilias Belharouak, ORNL’s scientist leading the NFA research and development, more than 100 million electric vehicles are anticipated to be on the road by 2030. Cobalt is a metal currently needed for the cathode which makes up the significant portion of a lithium-ion battery’s cost.

Cobalt is rare and largely mined overseas, making it difficult to acquire and produce cathodes. As a result, finding an alternative material to cobalt that can be manufactured cost effectively has become a lithium-ion battery research priority.

Researchers used neutron diffraction, Mossbauer spectroscopy and other advanced characterization techniques to investigate NFA’s atomic- and micro-structures as well as electrochemical properties.

Our investigations into the charging and discharging behavior of NFA showed that these cathodes undergo similar electrochemical reactions as cobalt-based cathodes and deliver high enough specific capacities to meet the battery energy density demands.

—Ilias Belharouak

Although research on the NFA class is in the early stages, Belharouak said that his team’s preliminary results to date indicate that cobalt may not be needed for next-generation lithium-ion batteries.

Belharouak said that not only does NFA perform as well as cobalt-based cathodes, but the process to manufacture the NFA cathodes can be integrated into existing global cathode manufacturing processes.

Lithium nickelate has long been researched as the material of choice for making cathodes, but it suffers from intrinsic structural and electrochemical instabilities. In our research, we replaced some of the nickel with iron and aluminum to enhance the cathode’s stability. Iron and aluminum are cost-effective, sustainable and environmentally friendly materials.

—Ilias Belharouak

Future research and development on the NFA class will include testing the materials in large-format cells to validate the lab-scale results and further explore the suitability of these cathodes for use in electric vehicles.

Additional researchers on the journal articles include Nitin Muralidharan, Rachid Essehli, Raphael Hermann, Ruhul Amin, Charl Jafta, Junje Zhang, Jue Liu, Zhijia Du, Harry Meyer, Ethan Self, Jagjit Nanda and Yaocai Bai.

The work was sponsored by DOE’s Office of Energy Efficiency and Renewable Energy Vehicle Technologies Office.

Resources

• Muralidharan, N., Essehli, R., Hermann, R. P., Amin, R., Jafta, C., Zhang, J., Liu, J., Du, Z., Meyer, H. M., Self, E., Nanda, J., Belharouak, I. (2020a) “Lithium Iron Aluminum Nickelate, LiNi_xFe_yAl_zO₂—New Sustainable Cathodes for Next‐Generation Cobalt‐Free Li‐Ion Batteries.” Adv. Mater. doi: 10.1002/adma.202002960

• Nitin Muralidharan, Rachid Essehli, Raphael P. Hermann, Anand Parejiya, Ruhul Amin, Yaocai Bai, Zhijia Du, Ilias Belharouak (2020b) “LiNi_xFe_yAl_zO₂, a new cobalt-free layered cathode material for advanced Li-ion batteries”, Journal of Power Sources, doi: 10.1016/j.jpowsour.2020.228389