Preparation and properties as positive electrodes of PANI–LiNi0.8Co0.2O2 nanocomposites

Abstract

PANI–LiNi_0.8Co_0.2O₂ nanocomposite material with improved properties as positive electrode was prepared by a new synthesis method. In a first step, LiNi_0.8Co_0.2O₂ mixed oxide in the form of a fine powder was dispersed in aniline and this suspension was sprayed on the surface of an aqueous solution of HCl and ammonium peroxodisulfate. The resulting PANI–LiNi_0.8Co_0.2O₂ nanocomposite is spontaneously formed by polymerization of the aniline molecules present in the drops together with small particles of the oxide. This method induces the formation of nanocomposites showing a better distribution of the oxide particles in the polymer matrix than that observed in related PANI–LiNi_0.8Co_0.2O₂ microcomposites prepared under ultrasound irradiation to disperse the oxide particles during PANI polymerization. Measurements of electrical conductivity and zeta potential, as well as structural characterization of PANI–LiNi_0.8Co_0.2O₂ nanocomposites, reveal the existence of relatively strong interactions between the conducting polymer and the oxide particles. This feature determines higher values of the electrical conductivity (0.5 S cm⁻¹) and of the average operative voltage (3.6 V), as well as of other technological parameters of the nanocomposite when it is used as the positive electrode of rechargeable lithium batteries, in comparison to those of the related microcomposite materials already reported.