Efforts to develop better models of rechargeable batteries focus on research on better, solid solution for transporting the ions between the terminals of the battery. Current standard is dominated by lithium ion batteries that use a liquid electrolyte for the purpose, which at times has resulted these batteries to explode as the liquid is flammable. Over the past few years, the ionic mobilities of superionic crystal have been of increasing interest to material scientists.
Researchers collaborated from multiple labs and institutes in the U.S., notably including Argonne National Laboratory and Oak Ridge National Laboratory to probe the atomic dynamics of a class of such crystals containing a high-performance phonon glass called CuCrSe2. The researchers studied the superionic phase of the material using scattering studies with the help of neutrons and X-rays to understand how copper ions resemble the properties of liquid. They found that when the crystal is heated to more than 190 degrees F, the phase transition temperature, the copper ions break down to move as liquids inside the layers of the other two elements, selenium and chromium. They concluded that the anharmonicity and phonon dynamics of copper is responsible for imparting superionicity in these crystals.
Neutron Scattering and High-resolution X-ray Studies lay bare Crystal’s Detailed Atomic Structure
Getting a view of detailed atomic structure and dynamics for this class of materials has been a challenge, until now. The study gained from technologies present at two research laboratories: the Advanced Photon Source at Argonne National Laboratory and the Spallation Neutron Source at Oak Ridge. The researchers used high-resolution X-rays to study the vibration modes of chromium and selenium. They found that scaffold vibrations were directly responsible for the solid-like behavior of the material.
Future Research needed to Know Interaction between Copper Ions
The various findings of the study were validated using quantum simulations in the National Energy Research Scientific Computing Center. Interestingly, copper ions could flow like liquid when the crustal is above the phase transition temperature. However, the study is limited in scope as the scientists still don’t clearly understand how copper ions interact among themselves in the CuCrSe2 when heated above this temperature. Future research is needed, possibly involving variants of superionic crystal, to study their behavior.