Synthesis and electrochemical characterization of anode material with titanium-silicon alloy solid core/nanoporous silicon shell structures for lithium rechargeable batteries

Composite materials composed of titanium-silicon alloy (Ti-Si alloy) core and porous Si shell (core-shell (C/S) composite) are prepared, and their electrochemical performance as anode materials for lithium-ion batteries is reported. The C/S composites are fabricated by selective etching of the titanium silicide phase in the surface region of a Ti-Si alloy that consists of titanium silicide and Si phases. The Ti-Si alloy is mechanically alloyed (MA) by ball-milling a mixture containing elemental Si and TiH2. Prior to the etching treatment, some of the MA samples are annealed at temperatures ranging from 600 to 800 °C to further develop the crystalline structure; annealing leads to the increase in the crystallite size of the Si and silicide phases. Thereby, the core and shell structure of the C/S composites and their electrochemical behaviors are controlled. Electrodes prepared by blending the C/S composites with graphite show good cycle performance and rate capability.