Mapping of Transition Metal Redox Energies in Phosphates with NASICON Structure by Lithium Intercalation

The position of several transition metal redox energies with respect to the Fermi energy of lithium in phosphates with sodium super ionic conductor (NASICON) framework were determined electrochemically upon lithium intercalation. The materials studied were , and all having NASICON framework. The positions of the redox couples were found centered at the following energies: at 3.8 eV, at 2.8 eV, at 2.5 eV, at 2.2 eV, at 1.8 eV, and at 1.7 eV below the Fermi energy of lithium. Several of these redox couples were found to overlap each other. Some of these materials look promising as positive electrode materials for ‐ion batteries.