Ion transport across interfaces and solids

Interfacial ion transport plays a central role in batteries. The function of the battery relies on unimpeded ion transport between the two electrodes and across the electrolyte. In practice, the complex chemistry at the electrode-electrolyte interface, which typically results in formation of solid organic-inorganic phases deposited at the interface, can completely block ion transport.

We are interested in understanding this interfacial phenomenon: we aim to determine the chemical composition and the structure of  the interface as well as directly determine its effect on ionic transport. Based on this understanding we design ionically permeable surface layers that can be formed prior or during the battery’s operation.

Ion transport across liquid-solid and solid-solid interfaces is extremely challenging to probe. We develop new NMR based tools to do just that.  For example, we employ chemical exchange saturation transfer, a method which is typically used to gain contrast in MRI or to probe dynamics in biomolecules. Here we use this approach to “label” the ions that are undergoing exchange between the electrolyte and the interface or the phases at the interface and the electrode by saturating their NMR signal. We then follow their exchange process by monitoring the change in NMR signal, thereby tracking the path of the ions.

Such insight into interfacial chemistry and process can then be used to design electrode and electrolyte materials with beneficial properties.

some examples of how we probe ion tranport across interfaces:

  •  Lithium exchange across a lithium-less coating for high energy cathodes J. Power Sources (2023)
  • Direct Detection of Lithium Exchange across the Solid Electrolyte Interphase by 7Li Chemical Exchange Saturation Transfer J. Am. Chem. Soc. (2022)
  • Structure and Functionality of an Alkylated LixSiyOz Interphase for High-Energy Cathodes from DNP-ssNMR Spectroscopy J. Am. Chem. Soc. (2021)