Facile synthesis of graphite nitrate-like ammonium vanadium bronzes and their graphene composites for sodium-ion battery cathodes

Abstract

A simple and versatile method for preparation of new crystalline graphite nitrate-like ammonium vanadium bronze (NH₄)_0.19V₂O₅·0.44H₂O nano-microstructures is developed via a simple hydrothermal route following heat treatment. (NH₄)_0.19V₂O₅·0.44H₂O platelets are tested as a novel high-energy cathode material for sodium-ion batteries. The enhancement of electrochemical performance for a (NH₄)_0.19V₂O₅·0.44H₂O platelet electrode is offered by addition of graphene and using graphite nitrate-like ammonium vanadium bronze microflowers. A graphene-based graphite nitrate-like vanadium bronze microflower composite shows a higher discharge capacity of 208.9 A h g⁻¹ for the second cycle in a 1.5–3.4 V voltage limit at a discharge current density of 20 mA g⁻¹. The reversible capacity of 141.5 A h g⁻¹ remained after 40 cycles.