Orbital and Electrical Dual Function of Polymer Intercalant for Promoting NH4+ Storage in Vanadium Oxide Anode

The impact of polyaniline insertion on the atomic orbitals and electronic structure of vanadium oxide anode is systematically investigated for the first time. The electrode exhibits an outstanding capacity and unprecedent long-term cycling life, owing to the electron transition to the V 3d_xy state and the enhanced diffusion kinetics.

Abstract

Polymer-intercalated metal oxides have attracted considerable attention for ammonium ions (NH₄ ⁺) storage due to their enhanced interlayer space, which, through the pillar effect, facilitates rapid and efficient transport of NH₄ ⁺. However, the understanding remains limited regarding how polymer intercalants affect the intrinsic structure of host materials, especially the variations in atomic orbital and electronic structural induced by the intercalants. Herein, a polyaniline-intercalated vanadium oxide (P-VO _x ) is developed and, for the first time, its NH₄ ⁺ storage behavior is validated as an anode material. Using various spectroscopy techniques combined with theoretical simulation, the changes are analyzed in atomic orbital and electronic structure induced by the intercalant. Spectroscopy studies reveal that the insertion of polyaniline optimizes the electronic structure of V₂O₅, promoting the transition of electrons to the V 3d _xy state and increasing the occupation of the V t_2g orbital, thereby enhancing electrical conductivity. Computational results confirm that P-VOx lowers the NH₄ ⁺ migration barrier, thereby enhancing electron/NH₄ ⁺ transfer. As a result, the P-VO _x electrode demonstrates outstanding capacity and unprecedented long-term cycling stability. This study provides new insights into the atomic and electronic structural changes induced by the polymer intercalant and underscores the advantages of polymer-intercalated VO _x as a high-performance electrode for NH₄ ⁺ storage.