Low-cost Mn-based P2/O3 heterostructured layered oxide cathodes based on orbital-lattice synergistic modulation strategy for sodium-ion batteries
Manganese-based layered oxides are prospective cathodes for sodium-ion batteries (SIBs) due to high theoretical capacity and low cost, but the Jahn-Teller effect of Mn3+ (high-spin d4) induces irreversible phase transitions and lattice deformations. This study designs Ti-substituted P2/O3 heterostructured cathodes via an orbital-lattice synergistic modulation strategy. In situ XRD reveals that P2/O3 biphasic coupling suppresses the irreversible P2-to-O2 transition at high voltages. Synchrotron XAS shows that the d0 configuration of Ti4+ eliminates degenerate electronic states of Mn3+, mitigating Jahn-Teller distortion. The optimized P2/O3-Na0.85Mn0.95Ti0.05O2 (NMT-05) electrode delivers enhanced energy density and kinetics in half-cell and full-cell configurations paired with hard carbon anodes. This work provides guidelines for low-cost, highly stable Mn-based oxide cathodes.