Monodisperse Antimony Nanocrystals for High-Rate Li-ion and Na-ion Battery Anodes: Nano versus Bulk

We report colloidal synthesis of antimony (Sb) nanocrystals with mean size tunable in the 10–20 nm range and with narrow size distributions of 7–11%. In comparison to microcrystalline Sb, 10 and 20 nm Sb nanocrystals exhibit enhanced rate-capability and higher cycling stability as anode materials in rechargeable Li-ion and Na-ion batteries. All three particle sizes of Sb possess high and similar Li-ion and Na-ion charge storage capacities of 580–640 mAh g–1 at moderate charging/discharging current densities of 0.5–1C (1C-rate is 660 mA g–1). At all C-rates (0.5–20C, e.g. current densities of 0.33–13.2 Ag1–), capacities of 20 nm Sb particles are systematically better than for both 10 nm and bulk Sb. At 20C-rates, retention of charge storage capacities by 10 and 20 nm Sb nanocrystals can reach 78–85% of the low-rate value, indicating that rate capability of Sb nanostructures can be comparable to the best Li-ion intercalation anodes and is so far unprecedented for Na-ion storage.