SnO2 nanoparticles@polypyrrole nanowires composite as anode materials for rechargeable lithium-ion batteries

The SnO₂@polypyrrole (PPy) nanocomposites have been synthesized by a one-pot oxidative chemical polymerization method. The structure, composition, and morphology of the as-prepared SnO₂@PPy nanocomposites are characterized by XRD, FTIR, TG, SEM, and TEM. Electrochemical investigations show that the obtained SnO₂@PPy nanocomposites exhibit high discharge/charge capacities and favorable cycling when they are employed as anode materials for rechargeable lithium-ion batteries. For the SnO₂@PPy nanocomposite with 79 wt% SnO₂, the electrode reaction kinetics is demonstrated to be controlled by the diffusion of Li⁺ ions in the nanocomposite. The calculated diffusion coefficiency of lithium ions in the SnO₂@PPy nanocomposite with 79 wt% SnO₂ is 6.7 × 10⁻⁸ cm² s⁻¹, while the lithium-alloying activation energy at 0.5 V is 47.3 kJ mol⁻¹, which is obviously lower than that for the bare SnO₂. The enhanced electrode performance with the SnO₂@PPy nanocomposite is proposed to derive from the advantageous nanostructures that allow better structural flexibility, shorter diffusion length, and easier interaction with lithium.