MXene-Derived LiV₃O₈ Nanorods for High-Performance Aqueous Ammonium-Ion Batteries

Aqueous ammonium-ion batteries offer safe and low-cost energy storage but are limited by the lack of electrode materials combining high capacity, fast kinetics, and long-term stability. Herein, MXene-derived LiV₃O₈ nanorods are synthesized via an in situ thermal conversion strategy as high-performance anodes. The open 1D architecture enables efficient ion transport, delivering a high capacity of 185 mAh g^-1 at 1 A g^-1, excellent rate capability of 93 mAh g^-1 at 10 A g^-1, and outstanding cycling durability. A dynamic storage mechanism involving reversible H⁺/NH₄ ⁺ co-intercalation and ion-exchange-driven phase transition to NH₄V₃O₈·H₂O is revealed, inducing a self-adaptive nanorod-to-nanowire structural evolution that continuously enhances ion transport and active surface area. Density functional theory calculations further reveal ultralow ammonium-ion diffusion barriers along the V-O chain direction and strong adsorption stabilized by hydrogen-bond interactions, providing atomic-level insight into the fast kinetics. Full cells with δ-MnO₂ cathodes exhibit high voltage output and long-term stability, demonstrating practical feasibility.