birnessite

Complex nanostructures with multi-components and intricate architectures hold great potential in developing high-performance electrode materials for lithium-ion batteries (LIBs). Herein, we demonstrate a facile self-templating strategy for the synthesis of metal vanadate nanomaterials with complex chemical composition of NiCo₂V₂O₈ and a unique yolk–double shell structure. Starting with the Ni-Co glycerate spheres, NiCo₂V₂O₈ yolk–double shell spheres are synthesized through an anion-exchange reaction of Ni-Co glycerate templates with VO₃⁻ ions, followed by an annealing treatment. By virtue of compositional and structural advantages, these NiCo₂V₂O₈ yolk–double shell spheres manifest outstanding lithium storage properties when evaluated as anodes for LIBs. Impressively, an extra-high reversible capacity of 1228 mAh g⁻¹ can be retained after 500 cycles at a high current density of 1.0 Ag⁻¹.

Yolk–double shell NiCo₂V₂O₈ spheres have been successfully synthesized through a facile self-templating approach using the ion-exchange reaction between Ni-Co glycerate spheres and NH₄VO₃ under reflux conditions, followed by a thermal treatment in air. The as-synthesized NiCo₂V₂O₈ samples exhibit outstanding electrochemical properties when used as an anode material for lithium-ion batteries.