One-pot synthesis of core–shell-structured tin oxide–carbon composite powders by spray pyrolysis for use as anode materials in Li-ion batteries

Core–shell-structured tin oxide–carbon composite powders with mixed SnO2 and SnO tetragonal crystals are prepared by one-pot spray pyrolysis from a spray solution with tin oxalate and polyvinylpyrrolidone (PVP). The aggregate, made up of SnOx nanocrystals (several tens of nanometers), is uniformly coated with an amorphous carbon layer. The initial discharge capacities of the bare SnO2 and SnOx–carbon composite powders at a current density of 1Ag−1 are 1473 and 1667mAhg−1, respectively; their discharge capacities after 500 cycles are 78 and 1033mAhg−1, respectively. The SnOx–carbon composite powders maintain their spherical morphology even after 500 cycles. On the other hand, the bare SnO2 powder breaks into several pieces after cycling. The structural stability of the SnOx–carbon composite powders results in a low charge transfer resistance and high lithium ion diffusion rate even after 500 cycles at a high current density of 2Ag−1. Therefore, the SnOx–carbon composite powders have superior electrochemical properties compared with those of the bare SnO2 powders with a fine size.