Energy-dense fluoride batteries are exciting, but they only work at high temperatures. A collaboration of researchers recently discovered a new liquid electrolyte. It conducts fluoride in fluoride-based rechargeable batteries at room temperature. These batteries pack a major energy punch. As part of the study, the team used three Department of Energy user facilities. For example, they used the Titan supercomputer at the Oak Ridge Leadership Computing Facility to understand and refine the electrolyte’s unprecedented ability to conduct fluoride ions and retain chemical stability at room temperature. The breakthrough material is the first of its kind in the battery world.
Energy-dense fluoride batteries could hold up to eight times more charge than lithium batteries. Simulations such as the ones done can help scientists understand battery interactions and improve existing and newly discovered electrolytes. The understanding of the new electrolyte, called BTFE, gives researchers a map for the mechanisms involved in stabilizing fluoride batteries. Also, it could aid in the development of new kinds of batteries for use in cars, cell phones, or other electronic devices.
Researchers discovered a new liquid electrolyte named BTFE. The electrolyte could replace the molten salt currently used in fluoride-based batteries. The researchers studied the electrolyte and related materials using scanning transmission electron microscopy/electron energy loss spectroscopy at the Molecular Foundry. They used the computing resources at National Energy Research Scientific Computing Center and the Oak Ridge Leadership Computing Facility to run complex calculations and simulations. For example, they conducted molecular dynamics simulations on the Titan supercomputer to look at BTFE’s reactions with fluoride. The new solvent worked and made the fluoride ions stable enough to shuttle from the battery’s anode to the cathode, but the team didn’t quite know why before the simulations. They found that positively charged regions in BTFE were strongly interacting with the negatively charged fluoride to dissolve it. The team simulated many different solvents and positively charged ions—including a solvent that could potentially expand the voltage window of BTFE and make it even more stable. Follow-up studies on the project can aid in the optimization of new liquid electrolytes such as BTFE, enabling the possibility of fluoride-based batteries.
The research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This research used computational resources from the Oak Ridge Leadership Computing Facility at the Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy (DOE). This research also used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science user facility supported by the DOE Office of Science. Scanning transmission electron microscopy/electron energy loss spectroscopy work at the Molecular Foundry was supported by the DOE Office of Science, Office of Basic Energy Sciences. The research was supported by the National Science Foundation (V.K.D., T.F.M); and Resnick Sustainability Institute (M.A.W.). The team acknowledges support from the Beckman Institute of the California Institute of Technology to the Molecular Materials Research Center.
V.K. Davis, C.M. Bates, K. Omichi, et al., “Room temperature cycling of metal fluoride electrodes: Liquid electrolytes for high-energy fluoride ion cells.” Science 362, 6419 (2018). [DOI: 10.1126/science.aat7070]