BatteryTaking 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.