Operando PDF and XAS studies on amorphous phases in Na-ion battery anodes

Active materials for anodes of Na-ion batteries operating under conversion/alloying mechanisms offer higher capacities than conventional intercalation materials but struggle with stability over many cycles. Their complex cycling mechanisms, when a material undergoes through a series of transformations combining crystalline and amorphous phases, make them challenging to understand on the basis of chemical structures even with the most informative operando techniques [1,2]. This experiment will focus on two main groups of materials: Bi and Sb-based compounds for Na-ion batteries. Both types of materials create amorphous phases during cycling that we want to characterize with operando PDF to get a more complete understanding of their cycling mechanism. To do this we want to employ the use of multivariate analysis, allowing the separation of signals for easier analysis. For the Bi and Sb compounds, we also want to use operando XAS (XANES and EXAFS) to obtain element specific information.