Coal

NETL-developed device detects cobalt in coal byproducts, a potential boon for EVs

Being able to use U.S. coal byproducts as a source for cobalt could put the nation in a better position to address geopolitical competition.
NETL-developed device detects cobalt in coal byproducts, a potential boon for EVs
(The National Energy Technology Laboratory campus near Pittsburgh. Credit: NETL)

Researchers working at the Energy’s Department’s National Energy Technology Laboratory (NETL) created what they said is a compact, portable device that can be used to detect cobalt at low concentrations in liquids, such as process streams from coal byproducts like fly ash, and to prospect for cobalt in acid mine drainage.

Cobalt is used in lithium-ion batteries for many electric vehicles. The NETL innovation could offer financial, environmental and geopolitical implications for recovering the element that is currently produced mostly in the Democratic Republic of Congo, China and Zambia.

The primary working components of lithium-ion batteries in electric vehicles and consumer products are the anodes and the cathodes. Cobalt is incorporated into cathodes to prevent them from overheating or catching fire and helps extend battery life. It is also among the most expensive components in terms of total material costs for the batteries.

Researchers found that coal byproducts can be a source for the element, but low concentrations make it difficult to detect the element to recover it. Analyses of the process streams can be expensive and typically requires use of an inductively coupled plasma mass spectrometer, which can cost up to $100,000 and is typically too large to take outside the laboratory.

NETL researchers created a rapid, inexpensive, and portable characterization technique that can reduce production costs. The system responds nearly instantly to the presence of cobalt with detection performance reported as comparable to a commercial fluorescence spectrometer but at significantly lower costs.

The NETL system uses carbon dots that are co-doped with phosphorus and nitrogen-containing molecules as the sensing materials. Carbon dots are carbon nanoparticles that are less than 10 nm in size, and may be derived from coal. 

The sensor is selective for cobalt in the presence of 13 of the most common metal ions encountered in coal byproducts. It was tested by detecting cobalt when spiked into an acid mine drainage leachate sample. 

Coal ash could be a future source of cobalt for use in lithium-ion batteries.

The team built upon the initial innovation to create another potential product: a test strip sensor that exhibits a selective and sensitive visual response to cobalt using a handheld ultraviolet lamp.

The systems for detecting cobalt, which is based on a NETL patented portable spectrometer design, was described in the Journal of Materials Chemistry C.

According to the Cobalt Institute, electric vehicles are accelerating cobalt demand, consuming 59,000 tonnes, or 34% of the global total in 2021. The institute predicted that cobalt demand will continue rising as the electric vehicle transition progresses. The institute estimated that 70% of coming growth will be from the electric vehicle sector.

About 74% of mined supply comes from the Democratic Republic of Congo and 72% of the total production is refined in China. Both countries have faced accusations of environmental and human rights abuses associated with cobalt mining. Most of the world’s cobalt, 98%, is produced as a byproduct from large-scale copper and nickel mines. The remaining 2% is extracted in Morocco and from some Canadian arsenide ores.

The Cobalt Institute estimated that cobalt will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries.

NETL said that being able to use U.S. coal byproducts as a source for cobalt could put the nation in a better position to address that geopolitical competition.

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