Electrochemical properties of C-coated Cu₆Sn₅ nanoparticles dispersed on carbon matrix prepared by spray drying process

Spherical hollow Cu₆Sn₅/C composite powders are prepared by a post-treatment of the precursor powders obtained by a scalable spray drying process. Metal citrates are formed by chelation of the Sn and Cu components with citric acid, and they have good drying properties under high water vapor pressure. Citric acid used as a chelating agent is a key material in synthesizing the composite powders. Decomposition and reduction of the precursor powders under reducing atmosphere produces phase-pure Cu₆Sn₅/C composite powders with unique morphology. Cu₆Sn₅ alloy particles coated with an amorphous carbon layer are uniformly dispersed on the inner and outer surface of spherically shaped carbon powders. The mean sizes of Cu₆Sn₅ alloy and carbon matrix particles are 0.4μand 7 μm, respectively. The discharge capacities of the composite powders reduced at 600°C and 800°C are 380 and 275 mAh g^-1, respectively, after 20 cycles at a constant current density of 300 mA g^-1. The corresponding capacity retentions are 93% and 89%, respectively.