ChEMS Seminar: Microscopic Insights into Conductivity and Stability of Solid Electrolyte Interfaces

Engineering Tower 652
Miaofang Chi

Center for Nanophase Materials Sciences
Oak Ridge National Laboratory, Oak Ridge, Tenn.

Abstract: Despite their different chemistries, novel energy-storage systems (e.g., Li- air, Li-S, all-solid-state Li batteries, etc.) share the same concept of using solid electrolyte materials to enable the use of lithium metal. An ideal solid electrolyte material must be highly ionically conductive and exhibit desirable stability with metallic lithium. Over the past several decades, new solid electrolyte materials were developed that demonstrated high conductivity, which is comparable to that of organic liquid electrolytes. However, unexpectedly high resistivity from grain boundaries and electrolyte-lithium interfaces is often observed, and is the major limitation in realizing the practical application of these materials. Due to spatial confinement and structural and chemical complications, experimentally probing these interfaces is challenging. Thus, the exact origins of the interfacial resistivity is unclear. Here, in situ and atomic-resolution scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) are used to study these interfaces. Oxide solid electrolytes, including Li0.33La0.55TiO3 (LLTO) and Al-Li7La3Zr2O12 (LLZO), and LIPON, are used as prototype materials. The atomic-scale origin of the high resistivity in LLTO, the dendrite propagation in LLZO and the low-rate capability in LIPON-based all-solid-state micro-batteries were elucidated. Our results provide significant insights into the rational design of solid electrolytes and their interfaces. At the end, I will introduce the use of STEM-based vibration spectroscopy, which was only very recently enabled, to study ion conduction behavior in lithium-ion conductors.

Bio: Miaofang Chi currently is a senior staff scientist at the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory (ORNL). She received her Ph.D. in materials science and engineering from University of California, Davis in 2008. Her primary research interest lies in the development and application of novel electron microscopy techniques for energy materials, especially on analytical functional imaging and atomic-scale in situ microscopy for battery materials and fuel cell catalysts. She received the ORNL Director’s Award for Outstanding Individual Accomplishment in Science and Technology and the ORNL’s Early Career Research Award, both in 2015. She recently was awarded the Burton Medal by the Microscopy Society of America (2016). Miaofang is the author and co-author of more than 150 peer-reviewed journal articles. She serves on the award committee at the Microscopy Society of America.


Host: Xiaoqing Pan