Synergistic effect of graphene and polypyrrole to enhance the SnO₂ anode performance in lithium-ion batteries

In this work, a synergistic effect of reduced graphene oxide (rGO) and polypyrrole (PPy) was studied in terms of their promotional role to enhance the capacity and cyclic stability of hollow SnO₂ anodes in lithium-ion batteries. The core-shell structured hollow SnO₂/rGO/PPy nanocomposites were synthesized using a hydrothermal method followed by an in situ chemical-polymerization route. Substantially improved cycling stability and rate capabilities are achieved on the SnO₂/rGO/PPy ternary anodes. The exceptional cycling performance is due to the hollow ternary core-shell structure covered with PPy buffer layers along with the graphene frameworks further benefiting Li⁺ diffusivity and electrical conductivity. The significantly increased Li⁺ diffusion coefficient improves rate performance and the large current charge and discharge. Thus, taking all of these benefits together including the hollow structures of SnO₂ particles, role of the buffer of PPy, and effective matrix of graphene, the ternary nanocomposites yield a robust architecture for anode materials in high-performance Li-ion batteries.