SnO2/polypyrrole hollow spheres with improved cycle stability as lithium-ion battery anodes

Abstract SnO 2 /polypyrrole (SnO 2 /PPy) hollow spheres were fabricated by a liquid-phase deposition method using colloidal carbon spheres as templates followed by an in-situ chemical-polymerization route. The obtained SnO 2 /PPy composite particles had a size of 610–730 nm. The thickness of inner shell (SnO 2 ) and outer shell (PPy) for composites was about 35 and 90 nm, respectively. As an anode for lithium ion batteries, the SnO 2 /PPy composites electrode showed superior rate capability and excellent long-term cycling performance. After a long-term cycling of 600 cycles at different current densities, a capacity of 899 mAh g −1 was achieved at the current density of 100 mA g −1 for SnO 2 /PPy composites. The excellent electrochemical performance was attributed to the synergistic effect between the PPy coating layer and the hollow SnO 2 spheres, which guaranteed vast lithium storage sites, good electronic conductivity, fast lithium ion diffusion, and sufficient void space to buffer the volume expansion.