Silicon/Carbon Anodes with One-Dimensional Pore Structure for Lithium-Ion Batteries

Abstract

Abstract : A series of composite electrode materials have been synthesized and characterized for lithium ion and sodium ion batteries. First, carbon-coated one-dimensional mesoporous (porous size: 50 nm) Si films was synthesized by electrochemical etching of crystalline silicon followed by CVD carbon coating. The one-dimension pore structure and carbon coating offer additional space and electric pathway to accommodate volume change and improve rate capability. The reversible capacity of over 1500 mAh/g was measured. Second, porous carbon/Si or Sn composites were synthesized by dispersing Sn or Si nanoparticles into soft-template polymer matrix followed by carbonization. These composites show enhance electrochemical performance compared to bare Si or Sn nanoparticles because the unique porous carbon structure provides space and mechanical support to accommodate the volume expansion and release stress/strain during electrochemical lithiation/delithiation. Third, homogenous Sn/C nanocomposite spheres were also synthesized using a spray pyrolysis method. Very small Sn nanoparticles ( 10 nm) were uniformly dispersed in carbon spheres with diameter of about 400 nm. This composite spheres displayed superior cycling performance with no capacity fading after 10 cycles due to small size and uniform distribution of tin nanoparticles in carbon frame. Forth, nano-sulfur dispersed mesoporous carbon electrode materials were synthesized by high temperature S infusing method. The electrochemical properties were evaluated for lithium ion and sodium ion batteries. It is found that the nano-sulfur dispersed mesoporous carbon electrode materials show excellent electrochemical performance bouth for both Li ion and Na ion batteries, making is attractive cathodes for next generation of rechargeable batteries. This is the first time to investigate the electrochemical properties of sulfur cathode for both Li ion and Na ion batteries.