
Cathode innovation makes sodium-ion battery an attractive option for electric vehicles
New cathode material for sodium-ion batteries is inspired by earlier work at Argonne that led to the lithium-ion batteries in the Chevy Volt and Bolt
Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have invented and patented a new cathode material that replaces lithium ions with sodium and would be significantly cheaper. The cathode is one of the main parts of any battery. It is the site of the chemical reaction that creates the flow of electricity that propels a vehicle.
“Our estimates suggest that a sodium-ion battery would cost one-third less than a lithium-ion one,” said Christopher Johnson, senior chemist and Argonne distinguished fellow. “Our battery program at Argonne has been studying sodium-ion batteries for well over a decade now, and our design for the cathode structure makes sodium-ion batteries an appealing alternative for budget-friendly and more sustainable electric vehicles.”
The innovative breakthrough by Johnson’s research team stems from his prior research with two other Argonne Distinguished Fellows—Michael Thackeray (retired) and Khalil Amine—on a new cathode material for lithium-ion batteries. That cathode is now part of the batteries that power the Chevy Volt and Bolt, as well as other electric vehicles.
The earlier cathode material is a lithium nickel-manganese-cobalt (NMC) oxide with a structure in which the atoms are arranged in layers. This structure allows easy insertion and extraction of lithium ions between the layers. These ions thus can move freely from the cathode to anode and back to charge and discharge the battery.
Drawing insights from the earlier research, Johnson’s team invented a layered oxide cathode tailored for sodium-ion batteries. This variation on the NMC cathode is a sodium nickel-manganese-iron (NMF) oxide with a layered structure for efficient insertion and extraction of sodium. The absence of cobalt in the cathode formula mitigates cost, scarcity and toxicity concerns associated with that element.
The team’s interest in sodium-ion batteries stems from their many advantages. Two are sustainability and cost. Sodium is far more naturally abundant and easily mined than lithium. It is thus a fraction of the cost per kilogram and much less susceptible to price fluctuations or disruptions in the supply chain.
