Theoretical scientists at Stanford University have identified a new class of materials that could lead to the development of more efficient solid-state lithium-ion batteries.
The materials—lithium, boron and sulfur— were identified after the team used a computer algorithm to screen more than 12,000 lithium-containing compounds in a materials database.
Within minutes the algorithm identified around 20 promising materials, including four little-known compounds made of lithium, boron and sulfur.
Their findings are published in a study in the journal ACS Applied Materials & Interfaces.
The study was written by senior author Evan Reed, an associate professor of materials science, and engineering study lead author Austin Sendek, a visiting scholar in Stanford’s Department of Materials Science & Engineering.
Sendek (pictured) said: “As we were looking at the candidates, we noticed that four lithium-boron-sulfur compounds kept popping up. Unfortunately, there wasn’t much about these materials in the existing scientific literature.
“All four compounds are chemically similar. So when the mixture breaks down, each compound will likely transform from a good conductor to another good conductor to another. That means the materials can withstand several cycles of breaking down before they decompose into a bad conductor that ultimately kills your battery.”
The researchers examined the four compounds using density functional theory, which simulates how the materials would behave at the atomic level.
They found lithium-boron-sulfur electrolytes could be about twice as stable as the leading solid electrolytes— with stability impacting the amount of energy per unit weight a battery can store.
Sendek said: “With a solid electrolyte you could potentially double the energy density of lithium-ion batteries and get that range above 500 miles— and maybe even start thinking about electric flight.”
The study also predicted that certain phases of the lithium-boron-sulfur materials could be three times better at conducting lithium ions than state-of-the-art solid electrolytes made with germanium.
The Stanford study provides a theoretical roadmap for future research. The next step is to synthesize all four lithium-boron-sulfur materials and test them in a battery.
Sendek said. “From what my experimentalist friends tell me, making these materials in the lab may be quite difficult. Our job as theorists is to point the experimentalists to promising materials and let them see how the materials perform in real devices.”
