Enhancing Ammonium-Ion Storage Capability of NH₄V₃O₈ via an Interlayer Defect-Modulation Strategy

Ammonium vanadates (NVO) have presented great potential in serving as host materials for ammonium ions, yet they are still impeded by sluggish ammonium-ion kinetics. Herein, an interlayer cation-modulation strategy is proposed to promote the ammonium-ion storage capability of the NH₄V₃O₈ cathode. By rationally modulating the number of interlayer ammonium ions, the proposed NVO possesses an expanded interlayer distance and weakened electrostatic repulsion between the stored NH₄ ⁺ and the NVO host, resulting in enhanced performance in both the three-electrode system and full-cell system. This work is anticipated to boost the application potential of NVO cathodes in aqueous ammonium-ion batteries.