Free-standing Ni–NiO nanofiber cloth anode for high capacity and high rate Li-ion batteries

• Low cost, free-standing, high capacity, highly stable, and environmentally benign nickel–nickel oxide (Ni–NiO) nanofiber cloth.
• Simple electrospinning and thermal oxidation synthesis process.
• Stable formation of the solid electrolyte interface (SEI).
• Capable of replacing graphite anodes and providing the performance needed in LiBs for the next generation of portable electronics and electric vehicles.

Here we present a low cost, free-standing, high capacity, stable, and environmentally benign nickel–nickel oxide (Ni–NiO) nanofiber cloth anode for Li-ion batteries. Ni–NiO nanofibers are fabricated by simple electrospinning and thermal oxidation processes which create a free-standing, core–shell nanofiber structure. The nickel backbone mitigates poor conductivity issues observed in Li-ion anodes due to repeated volume change during lithiation/delithiation. The Ni–NiO nanofiber anode possesses a high surface area compared to that of a slurry cast electrode which helps facilitate Li-ion diffusion into the active material. Electrochemical impedance spectroscopy indicates improved capability of current collecting metal (nickel in this case) to withstand volume change in our free-standing structure. Furthermore, scanning electron microscopy indicates the stability of the Ni–NiO nanofiber cloth anode in excess of 400 charge/discharge cycles, partly evidenced by the stable evolution of solid-electrolyte interphase. As an anode, the Ni–NiO nanofiber cloth shows impressive results with a gravimetric capacity of 1054 mA h g−1 at a current density of 2154 mA g−1 or 3 C (1 C=718 mA g−1), a long cycle life of more than 1500 cycles, and exceptional stability throughout its cycle life with a Coulombic efficiency >99%. Performance evaluation enables the Ni–NiO cloth material for next-generation high capacity, high rate, stable, and environmentally benign Li-ion batteries.

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