Optimizing Metal-Precursor Stoichiometry Toward Impurity-Suppressed and Structurally Reversible Iron-Manganese Phosphate Cathodes for Sodium-Ion Batteries.
Na4Fe3(PO4)2P2O7 (NFPP) is emerging as a promising cathode material for sodium-ion batteries owing to its robust polyanionic framework and low material cost. However, its practical energy density is restricted by the low operating potential of the Fe2 +/Fe3 + redox couple. Partial substitution of Fe with Mn introduces...