The electrical and electrochemical properties of poly(p-phenylene)-based carbon for lithium rechargeable batteries

Poly(p-phenylene) (PPP), electrically conductive polymer, was prepared from benzene by chemical reaction. And then disordered carbon materials were obtained by heat-treating PPP in a nitrogen atmosphere at 400, 600, 700, 800 and 1000°C for 1 hour. X-ray diffraction and FTIR were measured to determined fundamental structure of PPP-based carbon and also measured a electrical conductivity and temperature dependence of conductivity of PPP-based carbon to study the electrical properties. The carbon prepared by heat treatment showed a broad X-ray diffraction peak around 2θ-22.4° indicating disordered structure. The electrochemical properties of Li/carbon cells using an 1M LiPF₆ solution of ethylene carbonate (EC) and diethyl carbonate (EC) as electrolyte were studied by means of constant current cycle and cyclic voltammetry. Electrodes were charged and discharged at a current density of 0.1 mA/cm² between 0 to 1.5 V. First discharge capacity of 836.9 mAh/g exceeding 372 mAh/g of theoretical capacity of graphite was observed from PPP-based carbon electrode prepared at 700°C