A new polypyrrole/maghemite hybrid as a lithium insertion electrode

A new polypyrrole (PPY)/maghemite (gamma-Fe2O3) hybrid was prepared by modification of the surface of maghemite nanoparticles using polymerization of pyrrole on the surface. Fourier transform infrared (FTIR), X-ray diffraction and electron microscopy studies have proven that it was only a surface modification, keeping the core structure unchanged. Transmission electron micrographs have shown the presence of PPY on the intergrain surface between maghemite particles, leading to reduction of particle aggregation. The electrochemical lithium capacity has increased up to 270 mAh/g in the potential range between 1.3 and 4.3 V vs. Li at 8 mA/g. The modified samples showed an enhanced cyclability compared to the pristine one. (C) 2002 Published by Elsevier Science B.V.