Superhierarchical Nickel-Vanadia Nanocomposites for Lithium Storage
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2018 American Chemical Society. 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/V 2 O 5 nanocomposite is designed and synthesized using a simple electrodeposition process followed by a hydrothermal treatment. Hierarchical V 2 O 5 nanostructures are deposited directly on a Ni microchanneled current collector. Morphological characterization shows that two-dimensional V 2 O 5 nanosheets are uniformly distributed on the porous Ni substrate. A peony-like V 2 O 5 microstructure arises having a diameter of 4 m. The superhierarchical Ni/porous-Ni/V 2 O 5 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 V 2 O 5 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 V 2 O 5 nanostructured active materials, and the binder-free processing. This research shows significant promise for use of superhierarchical structures in future of rechargeable batteries.