Collaborative Research: Discovery of Multivalent Solid Electrolytes via Integrated Computations and Experiments

About This Grant

PART 1: NON-TECHNICAL SUMMARY The operation of batteries critically relies on the movement of charged ions through an electrolyte medium. If solids could be used as electrolyte rather than the flammable liquids employed today, the resulting devices would be safer. Furthermore, among the possible ions, magnesium and calcium carry twice the charge of lithium, the current technological incumbent, so batteries based on these metal ions could also store more energy while minimizing the use of critical materials. However, these "multivalent" ions have difficulty moving through solids, which has prevented their use in practical batteries. With support from the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, researchers at University of Texas at Austin and University of Illinois Chicago combine advanced computer simulations with laboratory experiments in a feedback loop to design materials that overcome this fundamental barrier. The simulations predict atomic structures and chemical compositions that should allow fast calcium or magnesium movement. The team then synthesizes the best candidates, measures their properties as electrolytes, and uses the results to refine the predictive models. Success in this work could lead to a new class of solid electrolyte batteries that combine high energy storage with safe operation. To enhance the impact of the research, the project aims to introduce undergraduates to cutting-edge scientific topics early in their career, conducts student exchange between institutions to enhance workforce development, and promotes wide exchanges of ideas through international symposia. These efforts advance fundamental knowledge in materials chemistry, train the next generation of scientists and engineers, and contribute to U.S. goals for innovation in energy and technologies with secure supply chains. PART 2: TECHNICAL SUMMARY Achieving fast conduction of multivalent ions through solids remains a fundamental challenge in solid state chemistry. With support from the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, this project integrates computational and synthetic exploration to identify and develop solid electrolytes with high conductivity for magnesium and calcium. The work focuses on broad families of mixed anion compounds of magnesium and calcium crystallizing in an anti-perovskite structure. The anionic sublattice is formed by different combinations of pnictides or rotatable cluster anions in order to assess their impact on ion dynamics. The technical approach involves first-principles calculations to screen candidate compounds that are chemically stable, exhibit rotatable anions, and possess low ion-migration barriers. In parallel, the team pursues the synthesis of predicted phases to validate and enhance computations. After successful synthesis of promising candidates, the atomic structure and ion transport are measured using X-ray diffraction, impedance spectroscopy, and nuclear magnetic resonance techniques. Lastly, to further enhance the movement of ions, predictions are used to guide the experimental introduction of aliovalent dopants on the anion sublattice to generate cation vacancies. This integrated theory-experiment approach seeks to establish design principles for fast multivalent-ion conduction in solid electrolytes that push new boundaries in the movement of ions through solids while informing the development of batteries with unique performance. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.