Nanoscale changes unveiled in solid-state batteries to enhance performance

Researchers from the University of California San Diego, working with an international team, have made nanoscale discoveries that could improve solid-state battery performance. By using X-ray experiments and computer simulations, researchers were able to see why lithium ions move slowly in solid electrolytes. They discovered that faster vibrations at the interface made it more difficult for lithium ions to move there than in the rest of the material. This finding, published in Nature Materials, could lead to new strategies for enhancing the conductivity of solid-state batteries. Solid-state batteries with solid electrolytes hold promise as a safer, longer-lasting, and more efficient alternative to traditional lithium-ion batteries. However, limited lithium ion movement is a major issue, especially where the electrolyte and electrode meet. Professor Tod Pascal, co-senior author and member of the Sustainable Power and Energy Center, said that understanding how lithium ions move through the battery can help develop ways to transport them more efficiently.

Researchers from the University of California San Diego have developed a new technique to understand what happens at the interface between two solids in solid-state batteries. The method involves combining two existing approaches: X-ray absorption spectroscopy, which identifies a material’s atomic structure, and second harmonic generation, which identifies atoms at an interface by hitting them with consecutive pulses of high-energy particles. This allowed the researchers to probe lithium ions at the interface between a lithium lanthanum titanium oxide solid electrolyte and a lithium cobalt oxide cathode. They verified their results with computer simulations and found that the signals matched exactly. The technique provides a new way to examine functional interfaces, such as those present in batteries, and could help improve solid-state batteries’ performance.

Unlocking ion movement at the interface

The researchers, Jamnuch and Pascal, made significant progress by combining two established approaches in their study of solid-state batteries. Using X-ray adsorption spectroscopy and second harmonic generation, they were able to identify atomic structures and vibrations at the interface of the solid electrolyte material. They found that high frequency vibrations were occurring at the interface, and these vibrations were causing resistance to the movement of lithium ions, in addition to the incompatibility between the solid electrolyte and electrode materials.

Pascal described this resistance as similar to a ball bouncing inside a room where the walls were also moving. The faster the walls move, the more time the ball spends bouncing around, and the longer it takes to reach the front. Similarly, in solid-state batteries, the path that lithium ions take to get through the material is impacted by high frequency vibrations, which cause them to move more slowly.

The researchers’ computational work revealed that one way to make it easier for ions to get through the material is to slow down the vibrations at the interface. One way to achieve this would be to dope the interface with heavy elements. These findings open up new possibilities for designing solid-state batteries that are more efficient and have better performance.

Source: University of California – San Diego

Leave a Comment