Spectroscopic Signatures in Na$_x$MnO$_2$ Cathodes for Na-ion batteries: A Computational Study Based on Density-Functional Theory

by Ms Valentina Sanella (PSI/LMS)

Wednesday 18 Nov 2026, 15:00 → 16:00 Europe/Zurich

OVGA/200

Layered sodium manganese oxides (Na$_x$MnO$_2$) are key cathode candidates for Na-ion batteries, yet their performance is governed by complex phase transitions, Jahn-Teller distortions, and competing cationic versus anionic redox mechanisms.

Here, we establish microscopic spectroscopic signatures capable of distinguishing local Na/vacancy ordering, Mn charge states, and oxygen redox activity in P2-Na$_x$MnO$_2$. Using density functional theory with self-consistent Hubbard U and V parameters computed with density-functional perturbation theory, we determine ground-state geometries and voltage profiles, paired with Bethe-Salpeter equation calculations of Mn and O K-edge X-ray absorption spectra (OCEAN code). Hubbard parameters correctly capture Mn(III)/Mn(IV) charge ordering and Jahn-Teller distortions without empirical fitting. Stoichiometric phases display classic Mn redox with systematically shifting Mn K-edges. In contrast, cation-deficient, oxygen-rich phases exhibit high-voltage oxygen redox, characterized by a static Mn edge and emerging O pre-edge features.

This work highlights first-principles XAS simulations as a powerful diagnostic tool to decode local structural distortions and energy-storage mechanisms in functional battery materials.