A team at Duke University, in collaboration with the Department of Energy's Oak Ridge National Laboratory, has taken a step towards improving solid-state batteries. The research focused on a material called lithium phosphorus sulfur chloride (Li6PS5Cl), a contender for replacing the liquid electrolytes currently used in batteries. Published in Nature Physics, the study revealed that lithium ions can move through this solid superionic compound with a surprising ease similar to liquid electrolytes, which could lead to batteries that are safer, charge faster, and last longer.
Neutron scattering techniques at ORNL's Spallation Neutron Source (SNS), along with machine-learned molecular dynamics simulations at Lawrence Berkeley National Laboratory's National Energy Research Scientific Computing Center, were key to observing lithium diffusion in Li6PS5Cl. "Our research was about figuring out what is going on inside these materials using the power of neutron scattering and large-scale computer simulations," Duke University's associate professor Olivier Delaire told ORNL, stressing the importance of neutron scattering in the design of next-generation batteries.
While the advantages of solid-state electrolytes over their liquid counterparts have long been acknowledged – including higher energy density and increased safety – widespread adoption has been hindered by the production challenges and inferior ion mobility of solid-state electrolytes. The research team utilized neutrons, as opposed to other methods, because of their ability to detect lighter elements like lithium. According to ORNL, "Neutrons provide information about where things are happening that we wouldn’t be able to see otherwise," said Doug Abernathy, the SNS’s Direct Geometry Spectroscopy group leader, emphasizing the unique insights provided by neutron spectroscopy.
Employing SNS instruments such as the Wide Angular-Range Chopper Spectrometer and the Backscattering Spectrometer, the scientists could measure, and model lithium diffusion within the superionic compound. “Our findings are impactful because they open the door to optimizing conductivity of the ions inside the material, therefore unlocking a path to increasing battery performance," Naresh Osti, a neutron scattering scientist at ORNL, explained. The research opens possibilities for the development of solid-state batteries that could meet future energy storage demands.
This work received funding through the National Science Foundation's Designing Materials to Revolutionize and Engineer our Future program. It used resources at both SNS and the National Energy Research Scientific Computing Center - DOE Office of Science user facilities. UT-Battelle manages ORNL on behalf of DOE's Office of Science, which is committed to solving some of the most pressing challenges in the physical sciences. For more information on their initiatives, interested parties can visit energy.gov/science.
