“Electrolytes have billions of possible combinations of components – salts, solvents and additives – that we can play with. To make that number into something more manageable, we’re beginning to really use the power of AI, machine learning and automated laboratories.”Venkat Srinivasan, Argonne National Laboratory

Designing a battery is a three-part process. You need a positive electrode, a negative electrode and – crucially – an electrolyte that works with both electrodes.

An electrolyte is the battery component that transfers ions – charge-carrying particles – back and forth between the battery’s two electrodes during charging and discharging. For today’s lithium-ion batteries, electrolyte chemistry is relatively well-defined. For the future generations of batteries being developed around the world, including at the US Department of Energy’s (DOE) Argonne National Laboratory, the question of electrolyte design is still wide open.

“While we are locked into a particular concept for electrolytes that will work with today’s commercial batteries, for beyond-lithium-ion batteries the design and development of different electrolytes will be crucial,” said Shirley Meng, chief scientist at the Argonne Collaborative Center for Energy Storage Science (ACCESS) and professor of molecular engineering at the University of Chicago’s Pritzker School of Molecular Engineering. “Electrolyte development is one key to the progress we will achieve in making these cheaper, longer-lasting and more powerful batteries a reality, and taking one major step towards continuing to decarbonize our economy.”

In a paper in Science, Meng and her colleagues laid out their vision for electrolyte design in future generations of batteries.

According to Meng, even relatively small departures from today’s batteries will require a rethinking of electrolyte design. For example, switching from a nickel-containing oxide to a sulfur-based material as the main constituent of a lithium-ion battery’s positive electrode could yield significant performance benefits and reduce costs, if scientists can figure out how to rejig the electrolyte.

For other beyond-lithium-ion battery chemistries, like rechargeable sodium-ion or lithium-oxygen batteries, scientists will similarly have to devote considerable attention to the question of the electrolyte.

One major factor that scientists are considering in the development of new electrolytes is how they tend to form an intermediary layer called an interphase, which harnesses the reactivity of the electrodes. “Interphases are crucially important to the functioning of a battery because they control how the selective ions flow into and out of the electrodes,” Meng said. “Interphases function like a gate to the rest of the battery; if your gate doesn’t function properly, the selective transport doesn’t work.”

The near-term goal is to design electrolytes with the right chemical and electrochemical properties to form optimal interphases at both the battery’s positive and negative electrodes. Ultimately, however, researchers believe that they may be able to develop a group of solid electrolytes that would be stable at extreme (both high and low) temperatures and allow batteries with high energy to have much longer lifetimes.

“A solid-state electrolyte for an all-solid battery will be a game changer,” said Venkat Srinivasan, director of ACCESS, deputy director of the Joint Center for Energy Storage Research, and co-author of the paper. “The key to a solid-state battery is a metal anode, but its performance is currently limited by the formation of needle-like structures called dendrites that can short out the battery. By finding a solid electrolyte that prevents or inhibits dendrite formation, we may be able to realize the benefits of some really exciting battery chemistries.”

In order to speed up their hunt for electrolyte breakthroughs, scientists have turned to the power of advanced characterization and artificial intelligence (AI) to search digitally through many more possible candidates, accelerating what had been a slow and painstaking process of laboratory synthesis. “High-performance computing and artificial intelligence are allowing us to identify the best descriptors and characteristics that will enable the tailored design of various electrolytes for specific uses,” Meng said. “Instead of looking at a few dozen electrolyte possibilities a year in the lab, we’re looking at many thousands with the aid of computation.”

“Electrolytes have billions of possible combinations of components – salts, solvents and additives – that we can play with,” explained Srinivasan. “To make that number into something more manageable, we’re beginning to really use the power of AI, machine learning and automated laboratories.”

Automated laboratories incorporate a robot-driven experimental regime, in which machines can perform unassisted ever more carefully refined and calibrated experiments to eventually determine which combination of components will form the perfect electrolyte. “Automated discovery can dramatically increase the power of our research, as machines can work around the clock and reduce the potential for human error,” Srinivasan said.

This story is adapted from material from Argonne National Laboratory, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.