Bimetallic Intercalated Vanadium Oxide As a High-Performance Cathode for Aqueous Zinc Ion Batteries

In this paper, a bimetallic Na_0.13Mg_0.02V₂O₅·0.98H₂O (NMVO) material with an interlayer spacing of 11.67 Å was synthesized by a simple preintercalation method as a cathode for zinc ionic batteries (ZIBs). The large layer spacing provides a wide channel for the embedding of Zn²⁺, resulting in high reversible capacity and ion diffusion kinetics. In addition, by virtue of the high electronic conductivity of metal ions, NMVO exhibits excellent electronic conductivity under the combined action of Na⁺ and Mg²⁺ bimetallic intercalation. At the same time, preintercalation ions and structural water act as interlayer pillars to stabilize the layer structure of NMVO during the cycling process. The above reasonable structural design endows the NMVO with excellent electrochemical performance. The battery with NMVO cathode delivers a high initial capacity of 126 mAh g^-1 at 10 A g^-1, and still remains at 76% after 5000 cycles, providing 100 Wh kg^-1 energy density and 9.5 kW kg^-1 power density (based on the mass of cathode). This bimetallic intercalation structure provides a general feasible scheme for the design of vanadium-based electrode materials.