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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