Ni-Sn Alloy Carbon-containing Nanocomposites as Alternative Anode Materials to the Graphite Electrodes in Li-ion Batteries

摘要

Ni-Sn alloy powder is synthesized through a borohydride reduction with NaBH₄ in a mixture of aqueous solutions of NiCl₂· 6H₂O, and SnCl₂· 2H₂O at mass ratio Ni:Sn=45:55. The ratio is chosen in accordance with the Ni-Sn binary system phase diagram. Interemtallic Ni-Sn nanoparticles are also obtained applying a template technique which involves the use of a carbon-containing support (graphite, carbon powder, carbon foam). As a result carbon - containing nanocomposites are prepared. The samples which are Ni-Sn alloys and carbon-based nanocomposites are studied by scanning electron microscopy (SEM), energy dispersitive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. The influence of the different supports used on the morphology, structure, phase and surface elemental composition of the synthesized composite materials is investigated. The surface element composition has proven the existence of the Co and Sn. The ratio Ni: Sn=45:55 set in the intermetallic nanoparticles synthesis is approximately kept. Phases of Ni₃Sn₂, Ni₃Sn₄, Ni₃Sn, and NiSn₂ are achieved. They are in correspondence with the phase diagrams of the Ni-Sn binary systems. The obtained Ni₃Sn₄ phase according to literature is expected to show best properties as an electrode material. The samples are electrochemically tested by a cycling voltammetry as electrode materials in Li-ion batteries.