Monodisperse SnSb nanocrystals for Li-ion and Na-ion battery anodes: synergy and dissonance between Sn and Sb

Abstract

We report a facile chemical synthesis of monodisperse colloidal SnSb nanocrystals (NCs) via reaction between Sn NCs and SbCl₃ in oleylamine under reducing conditions. In comparison with individual Sn and Sb NCs and their mixtures, we show that through the creation of SnSb alloyed NCs the Li-ion storage properties are enhanced due to combination of high cycling stability of Sb with higher specific Li-ion storage capacity of Sn. In particular, stable capacities of above 700 and 600 mA h g⁻¹ were obtained after 100 cycles of charging/discharging at 0.5C and 4C rates, respectively (1C corresponding to a current density of 660 mA g⁻¹). Furthermore, Na-ion storage capacities of >350 mA h g⁻¹ and >200 mA h g⁻¹ were obtained at 1C and 20C rates, respectively. This study highlights the differences between Li- and Na-ion (electro)chemistries and the great utility of monodisperse NCs as model systems for understanding size and compositional effects on the performance of conversion-type electrode materials.