Synthesis of ZnO/polypyrrole nanoring composite as high-performance anode materials for lithium ion batteries

ZnO has attracted considerable attention as electrode material in lithium-ion battery (LIB) due to its theoretically high capacity. However, poor electronic conductivity and huge volumetric changes during cycling limit its industrial applications. In this work, polypyrrole nanorings (PNRs) were successfully prepared via the solution chemistry method using pyrrole (Py) as raw material, ammonium persulfate (APS) as oxidant, and cetyltrimethyl ammonium bromide (CTAB) as surfactant. The ZnO/PNR composite was synthesized with zinc oxide nanoparticles absorbed on the surface of PPy nanorings through the one-pot in situ sol-gel method. The composite shows a three-dimensional intertwined network structure where the size of polypyrrole nanorings ranges from 80 nm to 100 nm in diameter and the average size of uniformly distributed ZnO nanocrystals is 10.49 nm. The unique three-dimensional conductive framework can provide good electronic contact between the ZnO particles and buffer the volume variation during the lithiation/delithiation processes. As an electrode material for LIBs, the ZnO/PNR composite delivers a first cycle discharge capacity of 1658 mAh g^-1 and a capacity retention of 50.7% over 150 cycles at 200 mA g^-1, indicating high specific capacity and outstanding cycle stability.