Development and characterization of nanostructure tin alloys as anodes in lithium - Ion batteries

Several tin-antimony and tin-zinc nanostructure alloys were electroplated from an acid bath, on a copper foil, at current densities higher by an order of magnitude than the limiting current density. They have been characterized as potential high-capacity anodes for lithium-ion battery applications. SEM micrographs of the tin-based alloys reveal nanosize particles, which aggregate into larger agglomerates of fractal shapes. On the nanoscale, the zinc-tin alloys have house-of-cards or honeycomb morphology. The composition of one series of tin based alloys was Sn:Sb (atomic ratio) 1.4:1 to 9:1; another alloy consisted of Sn:Sb:Cu in the ratio 34:10:4. All contained about 5% carbon and about 20% oxygen. The zinc-rich tin alloys contain at least 80 atomic percent zinc (their electrochemical characterization will be reported elsewhere). Tin-based alloys with low antimony content, have high reversible capacity (up to 700mAh/g), low irreversible capacity (about 24%), a better rate capability, and a lower average working potential vs. Li. On the other hand, alloys rich in antimony have a longer cycle life, but poor rate capability and a high average working potential vs. Li. The addition of copper to the tin-based alloys improved cycle life and slightly reduced irreversible capacity.