Colloidal BiF ₃ nanocrystals: a bottom-up approach to conversion-type Li-ion cathodes

A facile colloidal synthesis of BiF3 nanocrystals (NCs) via thermal decomposition of bismuth(III) trifluoroacetate in oleylamine is reported. The NC size can be tuned from 6 to 40 nm by the adjustment of synthesis parameters. After removal of the capping surfactant molecules, BiF3 NCs were tested as a cathode material for Li-ion batteries. Close to theoretical Li-ion storage capacities of up to 300 mA h g(-1) at an average voltage of 3 V were obtained at a current density of 50 mA g(-1).