Following Function in Real Time: New NMR, MRI and Diffraction Methods for Studying Structure and Dynamics in Batteries and Supercapacitors
mpi-is 06 December 2012 - 06 December 2012 FKF
A full understanding of the operation of a device requires that we utilize methods that allow devices or materials to be probed while they are operating (i.e., in-situ). This allows, for example, the transformations of the various cell components to be followed under realistic conditions without having to disassemble and take apart the cell.
To this end, the application of new in and ex-situ Nuclear Magnetic Resonance (NMR) and magnetic resonance imaging (MRI) approaches to correlate structure and dynamics with function in lithium-ion and lithium air batteries, and supercapacitors will be described. The in-situ approach allows processes to be captured, which are very difficult to detect directly by ex-situ methods. For example, we can detect side reactions involving the electrolyte and the electrode materials, sorption processes at the electrolyte-electrode interface, and processes that occur during extremely fast charging and discharging. Ex-situ NMR investigations allow more detailed structural studies to be performed to correlate local and long-range structure with performance. In this talk, I will describe the use of NMR spectroscopy combined with X-ray scattering methods to probe local structure changes in lithium ion batteries, focusing on our work with the anodes material Si and LiVO2, on lithium air cathodes, and to investigate Li dendrite formation in lithium metal batteries. Finally, the application of NMR to examine double layer formation in electrolyticdouble layer capacitors (supercapacitors) will be described.