Coaxial carbon nanofiber/NiO core–shell nanocables as anodes for lithium ion batteries

Abstract

Hierarchically coaxial carbon nanofiber/NiO (CNF/NiO) core–shell nanocables for lithium ion batteries are prepared to coat α-Ni(OH)₂ on the surface of electrospun carbon nanofibers (CNF) by electrophoretic deposition, followed by thermal processing in air. In the coaxial CNF/NiO nanocables, a NiO shell of about 20 nm thick is formed by coating with nano-furs outward on the surface of a CNF core of 200 nm in diameter, which is the main factor for providing a three-dimensional (3D) structure. The NiO shells, comprising of abundant inner spaces on the surface of CNF and high conductivity of 1D CNF, are deeply dependent on the enhancement of electrochemical rate capability. Abundant inner spaces in the NiO shell and the interconnected network between nanocables facilitate the mass transfer. The CNF core with the cushioning effect created through the elastic deformation provides electrochemical stability by protecting both radial compression and volume expansion originating from NiO shells radially. The CNF/NiO nanocables deliver a high reversible capacity of 825 mA h g⁻¹ at 200 mA g⁻¹ after 50 charge–discharge cycles without showing obvious decay. The coaxial CNF/NiO nanocables increase not only electrochemical capability but also electrochemical stability.