Understanding Charge Compensation Mechanisms Using Hard X-Ray Core-Shell Spectroscopy Methods

Understanding the charge compensation mechanisms during electrochemical cycling of battery materials is of both fundamental and applied interest. X-ray absorption near edge spectroscopy (XANES), a bulk-sensitive probe of the unoccupied projected density of states, has been a workhorse technique that sheds light on oxidation state changes of the metal ions. However, the rising edge at the metal K-edge — the energy of which is often used in assigning oxidation state — is also affected by other factors such as ligand identity, covalency, coordination number, and metal spin state. In this talk, we will highlight the application of these hard X-ray spectroscopy methods to understand fundamental structure-function relationships of materials and systems relevant to electrochemical energy storage.