Core–shell structured hollow SnO2–polypyrrole nanocomposite anodes with enhanced cyclic performance for lithium-ion batteries

Abstract

Core–shell structured hollow SnO2–polypyrrole (PPy) nanocomposites (SnO2@PPy) with excellent electrochemical performance were synthesized using a hydrothermal method followed by an in situ chemical-polymerization route. The thickness of the polymerized amorphous PPy coating covering on the hollow SnO2 microspheres is about 25nm, demonstrated by microscopy images. As an anode in lithium ion batteries, the nanocomposite is capable of retaining a high capacity of 448.4mAhg−1 after 100 cycles with a coulomb efficiency above 97%. Compared to other reported SnO2 anodes, the enhanced cycling stability is attributed to the unique core–shell structure and a possible synergistic effect between the PPy coating layer and the hollow SnO2 spheres. The PPy coating not only prevents the possible pulverization of the hollow SnO2 spheres, but also prevents the SnO2/Sn spheres from aggregating. Furthermore, the hollow space within the SnO2 nanoparticles effectively mitigates the enormous volume change during charge–discharge cycling. Meanwhile, the Li+ diffusion coefficient in the hollow SnO2@PPy (21wt%) core–shell nanocomposite electrode is significantly improved compared to the hollow SnO2 microspheres electrode. Thus, these benefits from the PPy coating and the hollow SnO2 spheres are able to provide a robust architecture for lithium-ion battery anodes.