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. Then disordered carbon materials were obtained by heat-treating PPP in a nitrogen atmosphere at 400, 600, 700, 800 and 1000 degrees C for I hour. X-ray diffraction and FTIR were measured to determine the fundamental structure of PPP-based carbon and also measured an 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 2 theta=22.4 degrees indicating a disordered structure. The electrochemical properties of Li/carbon cells using an 1M LiPF6 solution of ethylene carbonate (EC) and diethyl carbonate (DEC) as electrolyte were studied by means of constant current cycle and cyclic voltammetry. Electrodes were charged and discharged at a current density of 0.1mA/cm(2) between 0 to 1.5V. First discharge capacity of 836.9mAh/g exceeding 372mAh/g of theoretical capacity of graphite was observed from the PPP-based carbon electrode prepared at 700 degrees C.