Surface-modified maghemite as the cathode material for lithium batteries

Abstract

The inorganic-organic hybrid maghemite (gamma-Fe2O3)/polypyrrole (PPy) was synthesized and evaluated as cathode-active material for room temperature lithium batteries. The nanometer-sized core-shell structure of the hybrid consisting of the maghemite core with surface modified by PPy was evidenced from the morphological examination. The cathode fabricated with the as-prepared hybrid material delivered an initial discharge capacity of 233 mAh g(-1) and a reversible capacity of similar to 62 mAh g(-1) after 50 charge-discharge cycles. A much higher performance with an initial discharge capacity of 378 mAh g(-1) and a reversible capacity of similar to 100 mAh g(-1) was achieved with the cathode based on the segregated active material, which was obtained by subjecting the as-prepared hybrid material to an additional ball-milling process. The study demonstrates the promising lithium insertion characteristics of the nanometer-sized core-shell maghemite/PPy particles prepared under optimized conditions for application in secondary batteries. (C) 2008 Elsevier B.V. All rights reserved.