Scientists are leading the way in creating a new method to develop electrolytes aimed at enhancing the energy efficiency and lowering the carbon footprint of electrochemical processes. Their goal is to enhance electrolyte effectiveness in areas like iron production for steel.
Electrolytes are essential for the operation of any battery. They act as the channel through which positive ions (cations) travel between the battery’s positive and negative electrodes. This movement allows batteries to release energy when in use and to store energy when charging. This entire process is known as electrochemistry.
Electrolytes play a crucial role in various electrochemical processes. For instance, they can facilitate the transformation of iron ore into refined iron or iron alloys. One of the main obstacles is ensuring the electrolyte remains stable under high-stress operating conditions and prevents side reactions that can undermine energy efficiency. Successfully overcoming this challenge could potentially replace the energy-hungry blast furnaces currently used in steel production, leading to a reduction in greenhouse gas emissions.
This is the goal of the newly established Center for Steel Electrification by Electrosynthesis (C-STEEL), a Research Center funded by the Department of Energy (DOE) and managed by Argonne National Laboratory.
In a recent scientific review, researchers from Argonne presented a novel approach to creating a new class of electrolytes applicable to a wide range of electrochemical processes. “With this strategy, scientists can develop electrolytes not just for electric vehicle batteries, but also for the low-carbon manufacturing of steel, cement, and other chemicals,” mentioned Justin Connell, a materials scientist at Argonne and one of the leaders at C-STEEL.
Typically, the electrolytes used in electric vehicle batteries consist of a salt dissolved in a liquid solvent. For instance, sodium chloride is a common salt, while water serves as a frequent solvent. The salt supplies the electrolyte with both cations and negatively charged ions (anions)—in the case of table salt, that’s chlorine. Although the combinations of salts and solvents in batteries are often intricate, a crucial factor for their operation is that the electrolyte remains charge neutral through an equal balance of anions and cations.
Previous studies have mainly concentrated on varying the solvent composition while maintaining a single salt at different concentrations. “We believe the best way to enhance electrolytes is through experimenting with different anions for the salt,” Connell indicated. “Altering the anion chemistry could enhance energy efficiency in electrochemical processes while also extending the electrolyte’s lifespan.”
In the current electrolytes, the solvent envelops the working cation during its transition between electrodes. In standard lithium-ion batteries for electric vehicles, for example, the cation is lithium, and the anion is a fluorine phosphate (PF6).
To create new electrolytes for various uses, the Argonne team is exploring the idea of pairing the working cation with one or multiple different anions in the electrolyte. When anions either partially or completely replace the solvent around the cation, these configurations are termed contact ion pairs.
With countless possible combinations of contact ion pairs, how can the best anion-cation match be determined for a specific application? To find out, the team is using experimental methods alongside computational analysis powered by machine learning and artificial intelligence.
The objective is to establish a set of guiding principles that will help identify the optimal contact ion pairs for the electrolyte tailored to the needs of steel production under C-STEEL. “With these guidelines, we hope to find a cost-effective, durable electrolyte that facilitates the most efficient process for producing iron for steel,” Connell stated.
The same principles will also be relevant for electrolytes designed for other decarbonized electrochemical processes and extend to lithium-ion batteries and other applications.
This research has been funded by the DOE Office of Basic Energy Sciences and the Laboratory Directed Research and Development program at Argonne. A related paper has been published in CHEM, with contributions from Connell, Stefan Ilic, and Sydney Lavan.
