Facile synthesis of hydrated magnesium vanadium bronze σ-Mg_0.25V₂O₅·H₂O as a novel cathode material for lithium-ion batteries

Square block-like σ-Mg_0.25V₂O₅·H₂O with an open layered framework has been successfully synthesized via a facile hydrothermal method. The entire synthetic process is efficient and economically beneficial. As a cathode material for lithium-ion batteries, the hydrated magnesium vanadium bronze exhibits a high reversible capacity and excellent cycling stability at high current rates. High discharge capacities of 294.2 and 221 mA h g⁻¹ can be obtained at the current densities of 20 and 100 mA g⁻¹, respectively. Meanwhile, the electrode achieves a capacity retention of 87.12% after 100 cycles at 100 mA g⁻¹ and has an excellent long-term cyclic stability with an average decay of 0.053% per cycle over 400 cycles at 800 mA g⁻¹. The structural stability and impedance variation of the σ-Mg_0.25V₂O₅·H₂O electrodes upon cycling have also been investigated. The excellent electrochemical performance suggests that the layered Mg_0.25V₂O₅·H₂O could be a promising candidate for the cathode material of lithium-ion batteries.