Researchers at the Department of Energy's Oak Ridge National Laboratory (ORNL) were the first to use neutron reflectometry to peer inside a working solid-state battery and monitor its electrochemistry. They discovered that its excellent performance results from an extremely thin layer, across which charged lithium atoms quickly flow as they move from anode to cathode and blend into a solid electrolyte.
“We want better batteries,” said ORNL's Andrew Westover, who co-led a study published in ACS Energy Letters with James Browning at the lab's Spallation Neutron Source. “That means more energy density, lower cost, faster and safer battery charging and longer life.”
Rechargeable batteries rely on lithium, a small metal atom that packs tightly into the negatively charged anode to maximize energy density. However, lithium is unstable with most electrolytes – a factor in flammability of smartphone, laptop and electric vehicle batteries that use liquid electrolytes.
“To fix the flammability issue, we want to switch to solid electrolytes,” Westover said.
Enter lithium phosphorus oxynitride, or LiPON, a solid electrolyte invented at ORNL nearly 30 years ago. “It's never been understood why it works really well,” Westover said. “We want to make what works with LiPON work on a much larger scale. But we have to understand it first.”
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