Evidence of Li metal stabilization with CsNO3 additive. Credit: Muhammad Mominur Rahman et al.
Researchers at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have developed a novel method to improve lithium metal battery functionality with the addition of an electrolyte additive. The additive improves charging rates while maintaining cycle life.
In the study, published in Nature Communications, researchers targeted the interphase responsible for preventing electrode degradation. Preventing this degradation allows lithium metal batteries to have similar charge and discharge cycles as their lithium-ion counterparts.
"We wanted to improve the charging rate of the current state-of-the-art lithium metal batteries," said Muhammad Mominur Rahman, a research associate at Brookhaven. "But we also wanted to stabilize the batteries with a more protective interphase so they would last longer."
Conducted as part of the Battery500 Consortium, the researchers are striving to develop a battery with an energy density of 500 watt-hours per kilogram. This energy density is not possible with the modern lithium-ion batteries powering today's devices, driving the researchers to turn to lithium metal batteries which rely on a lithium metal anode as opposed to lithium-ion batteries graphite anode.
"The lithium metal battery is attractive because it can give twice the energy density of a battery with a graphite anode," said Rahman. "But there are lots of challenges to tackle."
Analysis of the novel electrolyte revealed that the cesium nitrate increased the stabilization of the cathode in the lithium metal battery by preventing the breakdown of the transition metals that it is comprised of. Further analysis utilizing the Quick X-ray Absorption and Scattering (QAS) and the In situ and Operando Soft X-ray Spectroscopy (IOS) beamlines verified the accumulation of cesium on the lithium metal anode and nitrates on the cathode.
"Lithium metal batteries have come a long way, but they still have a long way to go. The interphase plays a key role in progress that still needs to be made," said Rahman. "Our work has created new opportunities for interphase engineering, and I hope that this will inspire others to look at the interphase differently so that we can accelerate the development of lithium metal batteries."