Taking a detailed look inside energy storage systems could help solve potential issues before they arise. A team of researchers from Brookhaven National Laboratory are doing just that by imaging the inner workings of a sodium-metal sulfide battery, leading them to understand the cause of degraded performance.
“We discovered that the loss in battery capacity is largely the result of sodium ions entering and leaving iron sulfide—the battery electrode material we studied—during the first charge/discharge cycle,” says Jun Wang, co-author of the study. “The electrochemical reactions involved cause irreversible changes in the microstructure and chemical composition of iron sulfide, which has a high theoretical energy density. By identifying the underlying mechanism limiting its performance, we seek to improve its real energy density.”
Performance degradation in charge/discharge cycles has been the main problem researchers encounter when pursuing sodium-ion battery research. While the battery’s performance points to degradation issues, not much was previously known about what caused this degradation.
This from Brookhaven National Laboratory:
Wang’s team set out to change that. Using a full-field transmission x-ray microscope (TXM) at Brookhaven’s former National Synchrotron Light Source (NSLS) and later the Advanced Photon Source (APS) at DOE’s Argonne National Laboratory (the instrument was temporarily relocated there when NSLS closed in 2015 and will return to Brookhaven when the new TXM beamline at the replacement facility, NSLS-II, is ready)—both DOE Office of Science User Facilities—the scientists imaged what happened as sodium ions were inserted into (sodiation) and extracted from (desodiation) an iron sulfide electrode over 10 cycles.
“Our full-field hard x-ray transmission microscope was critical because it provided nanoscale spatial resolution and a large field of view,” Wang says. “Other microscopes typically provide one or the other but not both.”
