Preparation process and properties of LiCoO2/PANI/dodecylbenzenesulfonate composite electrode materials

Composite materials that combine the lithium exchanging material LiCoO2 and the conductive polymer poly(aniline) (PANI) have been investigated regarding their possible application to electrode materials of lithium batteries. Such composite materials have been prepared by means of polymerization of aniline in acidic suspensions of LiCoO2 particles. PANI was synthesized by oxidative polymerization of aniline by ammonium persulfate in the presence of sodium dodecylbenzenesulfonate (SDBS) as a micellar template and dopant. The composite material consisted in LiCoO2 particles dispersed in a continuous matrix of PANI. The ribbon-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The conductive material had conductivity close to that of PANI because the LiCoO2 content of the composite material was low. The presence of the poorly conductive inorganic phase caused a significant loss of conductivity, showing that LiCoO2 blocked electronic transfers between PANI crystallites. Ammonium persulfate caused the loss of lithium from LiCoO2 when it was used at high concentration in the polymerization recipe. In this case a new phase made of Co3O4 formed by chemical decomposition of LixCoO2. Thin films prepared from stable suspensions of composite materials in water show comparable electrical performance to that measured for bulk materials.