A Nano-Rattle SnO@carbon Composite Anode Material for High-Energy Li-ion Batteries by Melt Diffusion Impregnation.

The huge volume expansion in Sn-based alloy anode materials (up to 360%) leads to a dramatic mechanical stress and breaking of particles, resulting in the loss of conductivity and thereby capacity fading. To overcome this issue, SnO@C nano-rattle composites based on <10 nm SnO nanoparticles in and on porous amorphous carbon spheres were synthesized using a silica template and tin melting diffusion method. Such SnO@C nano-rattle composite electrodes provided two electrochemical processes: a partially reversible process of the SnO reduction to metallic Sn at 0.8 V vs. Li/Li and a reversible process of alloying/dealloying of LiSn at 0.5 V vs. Li/Li. Good performance could be achieved by controlling the particle sizes of SnO and carbon, the pore size of carbon, and the distribution of SnO nanoparticles on the carbon shells. Finally, the areal capacity of SnO@C prepared by the melt diffusion process was increased due to the higher loading of SnO nanoparticles into the hollow carbon spheres, as compared with Sn impregnation by a reducing agent.