Monodisperse and Inorganically Capped Sn and Sn/SnO₂ Nanocrystals for High-Performance Li-Ion Battery Anodes

We report a facile synthesis of highly monodisperse colloidal Sn and Sn/SnO₂ nanocrystals with mean sizes tunable over the range 9–23 nm and size distributions below 10%. For testing the utility of Sn/SnO₂ nanocrystals as an active anode material in Li-ion batteries, a simple ligand-exchange procedure using inorganic capping ligands was applied to facilitate electronic connectivity within the components of the nanocrystalline electrode. Electrochemical measurements demonstrated that 10 nm Sn/SnO₂ nanocrystals enable high Li insertion/removal cycling stability, in striking contrast to commercial 100–150 nm powders of Sn and SnO₂. In particular, reversible Li-storage capacities above 700 mA h g^–1 were obtained after 100 cycles of deep charging (0.005–2 V) at a relatively high current of 1000 mA h g^–1.