Superhierarchical Nickel–Vanadia Nanocomposites for Lithium Storage

New materials are critically needed for advanced energy storage devices due to the limited performance of currently used electrodes. We report an alternative approach to fabricate a novel class of nanostructured cathodes with a three-dimensional configuration that shows superior performance. A superhierarchical Ni/porous-Ni/V₂O₅ nanocomposite is designed and synthesized using a simple electrodeposition process followed by a hydrothermal treatment. Hierarchical V₂O₅ nanostructures are deposited directly on a Ni microchanneled current collector. Morphological characterization shows that two-dimensional V₂O₅ nanosheets are uniformly distributed on the porous Ni substrate. A peony-like V₂O₅ microstructure arises having a diameter of ∼4 μm. The superhierarchical Ni/porous-Ni/V₂O₅ nanocomposite exhibits superior electrochemical performance as a binder-free cathode. Its maximum reversible discharge capacity reaches 165.6 mAh g^–1 at 0.2 C, which is higher than the theoretical capacity of bulk V₂O₅ cathodes. The capacity retains 90.9% and 72.4% after 100 cycles at 0.2 C and 500 cycles at 3.0 C, respectively. The stable rate capability is also confirmed. Our analysis indicates that such high performance is attributed to the synergistic effects of: the hierarchical structure, microchanneled Ni current collectors, two-dimensional V₂O₅ nanostructured active materials, and the binder-free processing. This research shows significant promise for use of superhierarchical structures in future of rechargeable batteries