Electrodeposited Sb and Sb/Sb2O3 Nanoparticle Coatings as Anode Materials for Li-Ion Batteries

Galvanostatically electrodeposited coatings of pure Sb or co-deposited Sb and Sb2O3 nanoparticles, prepared from antimony tartrate solutions, were studied as anode materials in Li-ion batteries. It is demonstrated that the co-deposition of 20−25% (w/w) Sb2O3 results from a local pH increase at the cathode (due to protonation of liberated tartrate) in poorly buffered solutions. This causes precipitation of Sb2O3 nanoparticles and inclusion of some of the particles in the deposit where they become coated with a protecting layer of Sb. Chronopotentiometric cycling of the deposits, which also were characterized using, e.g., SEM, TEM, and XRD, clearly showed that the Sb2O3-containing deposits were superior as anode materials. While the Sb/Sb2O3 coatings exhibited a specific capacity close to the Sb theoretical value of 660 mA·h·g-1 during more than 50 cycles, the capacity for the Sb coatings gradually decreased to about 250 mA·h·g-1. This indicates that the influence of the significant volume changes present upon the formation and oxidation of Li3Sb was much smaller for the Sb/Sb2O3 nanoparticle coatings. The improved performance can be explained by significant formation of Sb2O3 during the reoxidation, the presence of smaller Sb particles in the Sb/Sb2O3 coatings, and the formation of buffering nanoparticles of Li2O in a matrix of Sb during the first reduction cycle for the Sb/Sb2O3 deposits.