STRUCTURE AND PROPERTIES OF DEEPLY LI-DOPED POLYACENIC SEMICONDUCTOR-MATERIALS BEYOND C6LI STAGE

The structure and properties of deeply Li-doped polyacenic semiconduct or (PAS) materials have been investigated in association with their ut ilization as electrodes in rechargeable batteries. The doped lithium w as found neither in metallic nor in ionic states even in the most deep ly doped state (C2.2Li stage) by X-ray photoelectron spectroscopy (XPS ) measurements. It has also been confirmed that the PAS electrode has a large capacity (530 mA h/g) with good stability and reversibility. T hese results strongly suggest that the PAS can make an excellent anode material for secondary batteries. Finally, we discuss that the PAS do ped up to the C2Li stage can exhibit an energy density per volume as h igh as lithium metal.