In situ Raman study of PPP-based disordered carbon as an anode in a Li ionbattery

Electrochemical lithium insertion into polyparaphenylene (PPP)-based disord ered carbon was investigated using in situ Raman spectroscopy. The peak pos ition of the high frequency Raman band of 1605 cm(-1) indicates characteris tically at first no change up to 1.0 V and then the peak downshifts from 16 05 cm(-1) to 1588 cm(-1), and finally disappears presumably because of the decrease in optical skin depth giving rise to the conductivity change. For the charging process, the opposite change was observed with some degree of irreversibility in the peak position, reflecting the irreversible discharge /charge capacity of the electrode. The change in peak position is somewhat similar to that observed in well-ordered graphite, which reflects that char ge transfer occurs between the Li and the defective carbon layers, even in such a low heat treatment temperature material. (C) 1998 Elsevier Science S .A. All rights reserved.