Nickel/carbon core/shell nanotubes: Lanthanum nickel alloy catalyzed synthesis, characterization and studies on their ferromagnetic and lithium-ion storage properties

A method was developed to synthesize ferromagnetic nickel core/carbon shell nanotubes (Ni/CNTs) by chemical vapor deposition using Pauli paramagnetic lanthanum nickel (LaNi5) alloy both as a catalyst and as a source for the Ni-core. The Ni-core was obtained through oxidative dissociation followed by hydrogen reduction during the catalytic growth of the CNTs. Transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) analyses reveal that the Ni-core exists as a face centered cubic single crystal. The magnetic hysteresis loop of Ni/CNTs particle shows increased coercivity (446.42 Oe) than bulk Ni at room temperature. Furthermore, the Ni/CNTs core/shell particles were investigated as anode materials in lithium-ion batteries. The Ni/CNTs electrode delivered a high discharge capacity of 309 mA h g−1 at 0.2 C, and a stable cycle-life, which is attributed to high structural stability of Ni/CNTs electrode during electrochemical lithium-ion insertion and de-insertion redox reactions.