Cathodes play a key role in the function of sodium-ion batteries. Understanding their structure and structural evolution under various processes is critical to develop better materials and superior battery performance, whether it be lifetime or capacity.
In the present work, we investigate the ion-exchange mechanism of a commercially available Na[NixFeyMnz]O2 (NFM), an O3 type layered oxide. Specifically, we are focused on the Li – Na ion exchange behaviour, trying to understand to how to control Na extraction and Li insertion electrochemically.
Using 7Li and 23Na NMR (solution and solid-state), we are able to determine the local chemical environments around these elements in Li/Na-NFM materials. These data are coupled with compositional changes determined using inductively coupled plasma optical emission spectroscopy (ICP-OES) and bulk structural changes using X-ray diffraction (XRD) and chemical changes using Xray absorption spectroscopy (XAS). The presentation will highlight the work underway to observe the electrochemical ion-exchange process in situ via a variety of characterization techniques.