Raphaële Clément, an assistant professor of materials at UC Santa Barbara, is one of only eighteen junior faculty nationwide selected to receive a 2024 Camille Dreyfus Teacher-Scholar Award by the Camille and Henry Dreyfus Foundation. The highly esteemed award recognizes young faculty in the chemical sciences who have demonstrated excellence in both research and education. 

“The honor may be given in my name, but I think it’s more of an award for my research group,” said Clément, whose previous accolades include an Early CAREER Award from the National Science Foundation and the International Society of Electrochemistry’s Prize in Electrochemical Materials Science. “We’ve been working hard over the years to develop new methodologies, understand the working principles of batteries, and design new materials. None of that would have happened without my dedicated team.”

Clément explores new battery materials at a fundamental level, seeking to understand the links between their chemistry, their atomic structure, and their electrochemical performance. Her group has expertise in using magnetic resonance spectroscopy to characterize materials, specifically those that could be used in batteries. Magnetic resonance techniques are powerful in that they probe the local arrangement of atoms around selected species, (for example, lithium) in a material, by tracking interactions between nuclear and electronic spins, allowing Clément and her team to study the charge and discharge processes in battery materials at the most fundamental level. Her group has developed novel magnetic resonance techniques that, unlike more standard characterization methods, are not constrained by a material’s chemistry, or their arrangement of atoms. Regardless of whether the atoms are ordered or disordered, these techniques still provide details to understand what is taking place inside devices, even down to the most minute changes in the crystal and electronic structure.

As a Camille Dreyfus Teacher-Scholar, Clément will receive an unrestricted research grant of $100,000 to fund her group’s investigation of solid-state lithium-sulfur (Li-S) batteries. Compared to existing Li-ion batteries that contain nickel and cobalt, Clément says that Li-S batteries could offer a 10-fold boost in energy density and be cheaper to produce. 

“I see them as the next, next, next generation of batteries that are very energy dense, but we’re not quite there yet,” she explained. “This award provides funding to pursue an idea we’ve had for a while, but could not fund because it is exploratory in nature. The award will enable us to get preliminary results and test the applicability of our methods, and I see this project evolving into a much bigger one in a couple of years.”

Beyond a drastic increase in energy density, replacing cobalt and nickel, whose toxicity and mining practices (for cobalt), raw material availability, and cost have raised significant concern, with sulfur, which is non-toxic and the fifth most abundant element on Earth, would benefit both the environment and human lives. In her Dreyfus-funded project, Clément will explore how sulfur, when used as the cathode material, is able to store large amounts of lithium in a solid-state device, where the liquid electrolyte found in present-day Li-ion batteries is replaced by a solid electrolyte sandwiched between the two electrodes. Notably, the use of a solid electrolyte mitigates issues related to dissolution of the sulfur cathode in the liquid electrolyte (i.e. irreversible loss of active material) in present-day Li-S cell. She will study the reaction processes of these solid-state devices operando, that is, by collecting data in real time while the batteries are being charged and discharged. 

“There are a lot of questions that need to be answered to make solid-state Li-S batteries possible,” said Clément, questions such as how much battery stack pressure is required to ensure that there is enough contact between the component solid materials to enable an uninterrupted flow of ions between the electrodes and the electrolyte, and allow the battery to operate despite large volume changes at the electrodes (the sulfur cathode expands by 70% during lithium incorporation on discharge). “This project seeks to answer the initial question of whether we can adapt our methods to study solid-state batteries under high-pressure conditions, and understand the reaction mechanisms at play.” 

If she and members of her research group are able to gain that understanding, they will be able to continue their work toward a more energy dense and sustainable solid-state battery that can be operated at gradually lower pressure, e.g. by incorporating soft interfaces. Though the process won’t happen overnight, Clément expects her prior work to fuel future discoveries.

“I believe that the magnetic resonance tools we’ve already developed will have a meaningful impact on what I have proposed, because they are some of the best-suited methods to truly understand what is going on inside Li-S devices and optimize the chemistry and materials,” she said.